Polyimide composites have attracted more and more attention due to their excellent properties and wide application prospects in aerospace, rail transit, microelectronics and other fields. SiC@SiO2 whisker was prepared by oxidation of SiC whisker at 750 ℃, which formed mixed fillers with BN particles. The SiC@SiO2 whisker and BN were modified by a silane coupling agent and a titanate coupling agent, respectively. SiC@SiO2/BN/PI composites were prepared by in-situ polymerization. The structure and property of the fillers and composites were characterized. Whiskers and particles formed an effective pathway in the polyimide matrix, which promoted continuous improvement of the thermal conductivity of SiC@SiO2/BN/PI composites. When the total filler content was 45wt% and the mass ratio of whiskers to particles was 4 : 1, the thermal conductivity was increased to 0.95 W/(m·K). Mechanical properties of SiC@SiO2/BN/PI composites changed regularly with the type and amount of mixed fillers. The SiO2 layer blocks the communication of free electrons between the mixed fillers, and the decreasing range of electrical insulation performance of the SiC@SiO2/BN/PI composites declined.

Ternary chalcogenides I-V-VI2 compounds attract extensive attentions for thermoelectric applications due to their intrinsically low lattice thermal conductivity. AgBiSe2, as one of a few n-type semiconductors among these compounds, shows the potential to be a promising thermoelectric material. Therefore, this work focuses on its thermoelectric properties. According to the phase diagram of Ag2Se-Bi2Se3 system, the single phase region of (Ag2Se)1-x(Bi2Se3)x allows x to be varied in the range of 0.4~0.62. This large variation of x suggests a tunability of carrier concentration for this material. A broad carrier concentration of 1.0×1019~5.7×1019 cm-3 for single phased (Ag2Se)1-x(Bi2Se3)x is obtained through a composition manipulation, which enables a comprehensive assessment on electronic transport properties based on a single parabolic band model with acoustic scattering. The highest carrier concentration obtained in this work, approaching to the theoretical optimal one, leads to a peak ZT of 0.5 at 700 K. This work offers a well understanding of its transport properties and underlying physical parameters determining the thermoelectric performance.

In recent years, tin telluride (SnTe) has attracted considerable interest due to its potential thermoelectric application as a lead-free rock-salt analogue of PbTe. However, pristine SnTe samples show high thermal conductivity and low Seebeck coefficients, resulting in poor thermoelectric performance. In this study, the thermoelectric performance of SnTe was enhanced by well-designed multi-doping, where significantly reduced thermal conductivity and improved Seebeck coefficientswere achieved at the same time. The doped SnTe samples were prepared by hot pressing. The lattice thermal conductivity of SnTe samples is obviously decreased by alloying with Se and S. The transmission electron microscope shows the existence of larger amount of nano-precipitates and the lattice distortions in the alloyed samples. For example, the lattice thermal conductivity of SnTe0.7S0.15Se0.15 sample is reduced to 0.99 W•m-1•K-1 at 300 K. The results reveal that the Seebeck coefficients are improved by introducing In resonant state in the band structure of SnTe. The experiments suggest the effectiveness of designed multi-doping in the thermoelectric performance enhancement of SnTe, and a promising ZT of 0.8 at 850 K is achieved in Sn0.99In0.01Te0.7S0.15Se0.15. The discovery suggests that SnTe is a promising medium-temperature thermoelectric candidate.

Hierarchical spherical Bi2S3 particles with nanorod were synthesized by hydrothermal method, and then BiCl3/Bi2S3 composite powders with different molar ratios were consolidated into bulk samples by spark plasma sintering (SPS) technique. The addition of BiCl3 with appropriate amount not only increased the electrical conductivity, but also decreased the thermal conductivity of Bi2S3. The Bi2S3 sample doped with 0.5mol% BiCl3 shows a maximum electrical conductivity of 45.1 S·cm-1 at 762 K, which is much higher than that of pure Bi2S3 at 762 K (12.9 S·cm-1). The minimum thermal conductivity is 0.31 W·m-1·K-1 for the Bi2S3 sample doped with 0.25mol% BiCl3 at 762 K, which is lower than that of pure Bi2S3 (0.47 W·m-1·K-1)at the same temperature. The maximum ZT value of 0.63 at 762 K was achieved by Bi2S3 doped with 0.25mol% BiCl3, which is almost two times higher than that of pure Bi2S3(0.22).

SnS composed of low toxicity, low-cost and earth-abundant elements, has extensive attention in the field of thermoelectric research. The n-type SnS1-xClx (x=0, 0.02, 0.03, 0.04, 0.05, 0.06) polycrystalline bulk thermoelectric samples were prepared by mechanical alloying (MA) combined with Spark Plasma Sintering (SPS). Effect of Cl- amounts on the phase structure, microstructure and thermoelectric transport properties were systematically studied. Results show that introduction of Cl- enhances electron concentration which makes intrinsic p-type SnS change to n-type. With the amount of Cl- increasing, the Hall carrier concentration of n-type SnS semiconductor increases from 6.31×1014cm-3 (x=0.03) to 7.27×1015cm-3 (x=0.06) at room temperature. The maximum electrical conductivity of 408 S•m-1 the relatively high Seebeck coefficient of -553 μV•K-1 are obtained at 823 K for x=0.05 sample, which produces the maximum power factor of 1.2 μW·cm-1·K-2. Addition of Cl- can introduce point defects to scatter phonons, which makes the lattice thermal conductivity reduce from 0.67 W·m-1·K-1 (x=0) to 0.5 W·m-1·K-1 (x=0.02). The highest ZT~0.17 is obtained at 823 K for x=0.04 sample, which is 70% higher than that (ZT~0.1) of the pristine SnS.

PbTe-based compositions are considered as excellent thermoelectric materials for the mid-temperature. However, the toxicity of lead limits its wide application. SnTe compounds, an analogue of PbTe, has attracted much attention. However, its ultrahigh carrier concentration and the large lattice thermal conductivity leads to a low ZT value of SnTe. In this work,thethermoelectric performance of SnTe is synergistically enhanced by introduction of Sn and SnO2 from the disproportionation of SnO in the process of the hot press sintering. On the one hand, Sn can compensate the Sn vacancies and decrease the carrier concentration of SnTe, leading to a simultaneous enhancement on resistivity and the Seebeck coefficient. For instance, compared with the pristine SnTe, resistivity and the Seebeck coefficient increases from 6.5μΩ•m to 10.5μΩ•m and from 105μV•K-1 to 146μV•K-1,respectively, for the sample of SnTe-6mol% SnO at 873K. On the other hand, in-situ generated SnO2 nanoparticles are dispersedly distributed on the grain boundaries, leading to the multiscale phonon scattering and the reduced lattice thermal conductivity. The minimum lattice thermal conductivity value is 0.6 W•m-1•K-1 for the sample SnTe-6mol% SnO at 873K, which is ~33% reduction compared with that of the pristine SnTe. As a result, the maximum ZT value of 0.96 (~100% enhancement, compared with that of the pristine SnTe) at 873K is achieved for the sample SnTe-6mol% SnO.

As a type of medium-temperature thermoelectric materials, Mg2(Si,Sn) alloy thermoelectric materials have been widely concerned because of the low cost and environmental friendliness. Heavily Sb doping can effectively induce Mg vacancy so as to reduce the thermal conductivity in Mg2(Si,Sn)-based materials, but at the same time lead to a decrease of Seebeck coefficient. In this study, high-quality Mg2.12-ySi0.4Sn0.5Sb0.1Zny (y=0-0.025) samples were successfully synthesized by high temperature melting and vacuum hot-pressing method. Zn element was introduced into the heavily Sb-doped Mg2(Si,Sn) material to investigate the double doping effect on the electroacoustic transport properties. The results show that Zn-Sb double doping could effectively reduce the total thermal conductivity of Mg2(Si,Sn)-based materials by obviously suppressing the electronic thermal conductivity and at the same time enhance the Seebeck coefficient of Zn-doped samples, so as to compensate for the loss of electrical conductivity, and maintain high electrical performance. Significantly optimized thermal conductivity and electrical performance ultimately improve the thermoelectric figure of meritZT of the material. At 823 K, the maximum ZT of Mg2.095Si0.4Sn0.5Sb0.1Zn0.025 reached 1.42.

Thermoelectric materials enable the direct inter-conversion between electrical energy and thermal energy. However, the conversion efficiency is limited by complex interdependent thermoelectric parameters, while the high performance thermoelectrics should simultaneously possess excellent electrical transport properties and poor thermal conductivities. The diamond-like compound Cu2SnSe3 is a promising middle-temperature thermoelectric material. In this work, the phase (Cu2Sn0.93Ag0.07Se3) with excellent electrical transport properties and the phase (Cu1.91Ag0.09SnSe3) with poor thermal conductivities were obtained just through Ag doping on the Sn and Cu sites, respectively. Meanwhile, their Seebeck coefficients were also quite different. To combine their advantages, the composites of Cu2Sn0.93Ag0.07Se3 and Cu1.91Ag0.09SnSe3 were fabricated through mechanical mixing and sintering. Benefited from the same crystal structure and the similar lattice parameters for these two phases, the small-mismatch phase interface is supposed to scatter phonons with little influence to the electrons, especially at high temperature. Therefore, the thermoelectric performance is improved due to the synergistically optimized electrical and thermal transport properties, which are well supported by the effective media theory for the composite.

Taking the dual-sublayer BiCuSeO superlattice thermoelectric material as an object, equivalent mono- and dual-doped samples were prepared by substitution of Bi and Cu atoms in the corresponding [Bi2O2]2+ sublayer and [Cu2Se2]2- sublayer with isovalent La and Ag atoms. Their thermoelectric properties and the defect modulation mechanism were studied. The results showed that La-Ag dual-doped sample could combine the advantages of mono-doped samples to achieve an relative high carrier mobility while moderately increasing the carrier concentration, thereby maximizing the electrical conductivity. At the same time, it can also induce a potential band convergenceeffect, achieving the low average band effective mass and high density of states effective mass at the same time, which finally endowed Bi0.98La0.02Cu0.98Ag0.02SeO with simultaneous high carrier mobility and Seebeck coefficient, as well as the optimized power factor (PF=σS2). On the other hand, due to the strong point defect scattering on the heat-carrying phonons, the lattice and total thermal conductivities of these isovalent doped samples were further reduced, which finally optimized the figure of merit (ZT). As a result, a high ZT value of 0.46 was achieved at 755K in the La-Ag dual-doped sample, which was superior to that of the pristine sample (0.27 at 755 K) as well as the mono-doped counterparts. Present work demonstrates that heterolayer-isovalent dual-doping with La/Ag equivalent atoms in BiCuSeO can synergistically modulate its thermoelectric transport parameters with significantly improved thermoelectric performance.

Thermoelectric (TE) power generation technology is highly expected for various applications such as special power supply, green energy, energy harvesting from the environment and harvesting of industrial waste heat. Over the past years, the record of zT values of TE materials has been continuously updated, which would bode well for widespread practical applications of TE technology. However, the TE device as the core technology for the TE application lags behind the development of TE materials. Especially, the large-scale application of TE power generation technology is facing bottlenecks and new challenges. This reviewpresents an overview of the recent progress on TE device design and integration with particular attentions on device optimization design, electrode fabrication, interface engineering, and service behavior. The future challenges and development strategies for large-scale application ofthermoelectric power generation are also discussed.

Thermoelectric power generation via Seebeck effect features an unique advantage in converting large amount of distributed and low-grade waste heat into electricity. Thermoelectric materials have become a hot topic of research in the field of new energy materials, guided by the high figure of merit ZT. Although various mid-temperature thermoelectric materials were discovered, the industrial application of these materials, especially in power generation applications, progressed very slowly. The staggering interface technology associated with thermoelectric device restricted the advance of thermoelectric conversion technology. In this review, the bottleneck issues of utilizing Bi2Te3-based devices for power generation were used as an example to illustrate the critical interface technologies. The key issues at designing electrode contact interfaces were summarized, including low contact resistance, high bonding strength, and superior thermal chemical stability at high temperature. The recent progress on the metallization and interfacial barrier layer for typical materials of Bi2Te3, PbTe and CoSb3 were also reviewed.

With rapid development of sustainable energies and energy conversion technologies, application prospect of thermoelectric (TE) materials in power generation and cooling has received increasing attention. The requirement of improving TE materials with high figure of merit becomes much more important. How to obtain the low lattice thermal conductivity is one of the main concerns in TE materials. In this review, the influences of specific heat, phonon group velocity and relaxation time on the lattice thermal conductivity are discussed, respectively. Several typical features of TE materials with intrinsic low lattice thermal conductivity are introduced, such as strong anharmonicity, weak chemical bonds and complex primitive cells. Introducing multiscale phonon scatterings to reduce the lattice thermal conductivity of known TE materials is also presented and discussed, including but not limited to point defect scattering, dislocation scattering, boundary scattering, resonance scattering and electron-phonon scattering. In addition, some theoretical models of the minimum lattice thermal conductivity are analyzed, which has certain theoretical significance for rapid screening of TE materials with low lattice thermal conductivity. Finally, the efficient ways to obtain the low lattice thermal conductivity for TE property optimization are proposed.

High-throughput experiments aimed to promptly obtain the relationship among composition-phase-structure-performance with fewer experiments and screen out optimal material systems with optimized compositions. Up to now, high-throughput experiments are successfully applied in superconducting materials, fluorescent materials and giant magnetoresistance materials. Thermoelectric materials are functional materials that can realize the direct conversion between thermal energy and electrical energy and can be potentially applied in the fields of thermoelectric power generation and waste heat utilization. However, traditional preparation and characterization methods for thermoelectric materials have disadvantages of time consuming and low efficiency. Therefore, it is of great theoretical and practical significance to introduce methods and concepts of high-throughput experiments into development and optimization of new thermoelectric materials. In this paper, we summarize and discuss the existing high-throughput experimental preparation and characterization techniques with great application prospects in thermoelectric materials, including high-throughput sample preparation, composition-structure, and electro-thermal transport properties characterization, and then analyze the advantages and limitations of these high-throughput techniques. We hope to provide a reference for future high-throughput optimization and screening of thermoelectric materials.

Thermoelectric materials are a kind of energy conversion materials, which are extensively used in power generation or refrigeration. The key parameter that measure the performance of thermoelectric materials is the figure of merit ZT value, which requires material excellent electrical transport performance and low thermal conductivity. Standard first principles calculations on thermoelectric materials focus on small samples of materials, which is difficult to conclude general rules and propose new candidates. The Materials Genome Initiative speeds up the discovery and design of materials based on big data and high-throughput computational methods, which is promising in novel material screening. In thermoelectrics, first principles high-throughput calculations play an increasingly important role in the predicting and designing new materials. However, there are some drawbacks in the current high-throughput efforts for thermoelectric material screening, such as the demand of efficient high-throughput algorithms for transport properties, suitable tools for analyzing big data, etc. Solving these challenges strongly determines the efficiency and accuracy of high-throughput applications in thermoelectrics. This review summarizes several high-throughput theoretical methods and cases study on electrical and thermal transport properties in thermoelectric materials, and prospects the future trend of the combination of high-throughput and thermoelectric material research.

Sphere-like hierarchical Y zeolite was synthesized by a “steam-assisted conversion (SAC)” procedure. The as-synthesized samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption-desorption, solid-state nuclear magnetic resonance (NMR) spectra, and Fourier transform infrared (IR) spectroscopy. Results observed by SEM displayed that the as-synthesized Y zeolite was sphere-like polycrystalline aggregates composed of primary crystals with size of about 50-300 nm. These results exhibited that some polycrystalline aggregates were hollow Y zeolite spheres. Combined with characterization results of FT-IR, 29Si NMR, SEM, and TEM, a mechanism illustrating formation of the hollow Y zeolite polycrystalline spheres was proposed.

Here we report a novel surface modified bamboo charcoal/TiO2 (SMBC/TiO2) nanocomposites with high adsorption and photocatalytic property. SMBC were prepared by a wet oxidization method of cheap natural bamboo charcoal (BC) with good absorbent and chemical stabilities. After modification, high density of carboxyl groups were generated on the surface of BC, thus SMBC particles can be easily dispersed in water and have stronger interactions with TiO2 nanoparticles, which ensure SMBC uniformly coated on TiO2. And SMBC/TiO2 nanocomposties have much higher specific surface area than BC/TiO2, which could offer higher adsorption capacity. The saturated adsorption capacity of SMBC/TiO2 is approximately 1.6 times, 12.1 times as great as BC/TiO2 and pure TiO2, respectively. The synergetic effect of adsorption and catalysis endow SMBC/TiO2 composites much higher photocatalytic activity than BC/TiO2 and pure TiO2 for MB degradation, and the rate constant for MB photocatalytic degradation of SMBC/TiO2 was almost 7 times and 6 times as large as BC/TiO2 and pure TiO2, respectively.

Optical transition properties of trivalent rare earth ions in transparent luminescent materials can be investigated via Judd-Ofelt analysis. The traditional Judd-Ofelt analysis can not be applied to nontransparent powders since its absorption spectra are unable to be measured. Therefore, in this study, a procedure for calculating the Judd-Ofelt parameters was proposed by using defuse-reflection spectrum. Firstly, the defuse-reflection spectrum was transformed into relative absorption spectrum based on Kubelka-Munk function, and then the relative Judd- Ofelt parameters were confirmed from the relative absorption spectrum, at last the actual Judd-Ofelt parameters were obtained by using fluorescence decay data for calibrating the relative values. The method proposed for Judd-Ofelt parameters’ calculation was applied to Lu2O3:Er3+ phosphor prepared by solid-state reaction, and the method was confirmed. The obtained Judd-Ofelt parameters were examined by comparing the radiative transition rates of 4I13/2 derived from the absorption cross section with which obtained from usual route by using the Judd-Ofelt parameters. The present study demonstrated that the proposed Judd-Ofelt analysis route is reliable and practical.

Silica-based ceramic core was produced by fused silica as matrix material, corundum powder as mineralizer, and Al powder as additive. Effects of aluminum powder contents on the ceramic core regarding shrinkage rate, physical performance, and microstructure were investigated. Results showed that through sintering process, aluminum powder was oxidized to alumina, accompanying with volume expansion and weight gain, which reduced sintering and casting shrinkages of silica-based ceramic core. There is no obvious inhibitory effect on devitrification by Al powder in the sintering process. Due to increased looseness of core skeleton structure in the casting process, the high temperature creep deformation increased. The sample with 1wt% Al showed good comprehensive properties, of which three-dimensional direction of sintering shrinkage rate were 0.01%, 0.03%, 0.03%, respectively, and porosity rate, deflection bending strength were 28.58%, 0.57 mm, 12.1 MPa, respectively. All these data demonstrated that the new core materials can meet the requirement of directional solidification and be expected to improve the dimensional accuracy of the hollow turbine blade.

Calcium polyphosphate fibers (CPPF) were prepared by melt-drawing method. Effect of B2O3 with different mass fraction on degradation and mechanical properties of CPPF was studied. The obtained CPPF were characterized by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). Results showed that tensile strength and modulus of CPPF were improved obviously with increase of mass fraction of B2O3. Moreover, the surface morphology of CPPF was influenced by the introducing of B2O3. In addition, the degradation ratio and cracks on the surface of CPPF decreased with increase of B2O3 content. Tensile strength and modulus of CPPF with B2O3 loading of 9% increased sharply by 146% and 153% compared to neat CPPF, respectively. After 16 d, the mass loss ratio of CPPF with B2O3 loading of 9% in the degradation process is reduced by 31% compared to the neat CPPF.

Hierarchical semiconducting metal oxide is highly active due to its special stereostructure, which is potential adsorbent for dye contaminants. Precursors of MoO2 hollow spheres were successfully synthesized via a simple and one-step solvothermal method. And hierarchical α-MoO3 hollow microspheres were obtained after subsequent calcination at 400 ℃. Diameters of the α-MoO3 microspheres were about 600-800 nm which were assembled by nanorods with a width of 70 nm. The as-obtained α-MoO3 nanomaterials presented excellent adsorption performance for methylene blue (MB). MB removal percentage attained 73.40% in the first 5 min when the concentration of α-MoO3 absorbent was 0.5 g/L in MB solution at the concentration of 20 mg/L. The equilibrium was established after adsorption for 60 min, and the removal percentages stabilized in the range of 97.53%-99.65%. Their adsorption kinetics was well fitted to a pseudo-second-order model. The adsorption isotherm conformed to Langmuir isotherm model, and the maximum uptake capacity was 1543.2 mg/g. The α-MoO3 microspheres are cost-effective, fast and complete for MB removal owing to its hierarchical and hollow nanostructures, which also can be employed for adsorption of other organic dyes in waste water.

The varied-valence nanocatalyst MnOx was prepared using the oxidation-reduction method under ultrasonic. The optimal synthetic conditions of MnOx were explored by adjusting the ultrasonic time, concentration of reaction precursor, drying temperature, and pH of reaction solution. The results indicated that the optimal sample MnOx was synthesized under the condition of ultrasonic time of 20 min, 0.5 mol/L KMnO4, drying temperature of 80 ℃ and pH=7, which showed the super catalytic performance and the time of 100% NO removal rate was as high as 15 h at room temperature. The structure and morphology of the optimal catalyst MnOx were investigated by XRD, N2-adsorption-desorption analysis, SEM and TEM. Besides, XPS and FT-IR were also applied to explore the catalytic oxidation process of NO removal and the deactivation mechanism of the optimal sample MnOx. It is believed that the interpenetrating and hierarchal pore, the petaloid morphology and weak crystallization structure contribute to the gas adsorption and transmission. The presence of varied-valence Mn and oxygen vacancy can improve the adsorption and activation of NO and O2, thus, enhancing the NO catalytic removal on the optimal catalyst MnOx at room temperature.

Acid sites located inside the 8-ring side-pockets of mordenite are highly active for DME carbonylation. However, mordenite deactivates very fast during the reaction because of non-selective reactions happening inside the 12-ring main channels of zeolites. In the present study, HMOR was treated by acid leaching using acetic acid of different concentration, with the purpose to selectively remove framework Al which is located inside 12-ring channels. Physicochemical characteristics of the parent and acid-treated mordenites were studied by complementary methods including: XRD, 27Al-NMR, NH3-TPD, pyridine IR, and N2 adsorption-desorption. The results show that the acid treatment, if appropriately applied, increases both the Si/Al and micropore volume of the samples, without significantly changing the mesopore size distribution. Most of the framework Al species in the 12-membered ring channels of HMOR were removed, without impacting those located inside the 8-ring channels. The catalytic results show that the initial activity of catalyst decreased slightly from 45.6% to 43.8%. On the other hand, the activity stability improved substantially, with stabilization period prolonged obviously from 18 h to 50 h.

Pt/hierarchical ZSM-5 zeolites were successfully synthesized by the steam-assisted crystallization and subsequent wetness impregnation method. Structural features were characterized by XRD, N2 isotherm, SEM, and TEM. Its catalytic behaviors for o-xylene storage at room temperature, and catalytic combustion of stored o-xylene at elevated temperatures were evaluated. It was found that crystallinity of the product underwent a reducing tendency after introduction of mesostructure, but the mesoporosity and pore volume were remarkably increased. Compared with Pt/conventional ZSM-5 zeolite, the o-xylene adsorption capacity of Pt/hierarchical HZSM-5 was around 8 times as that of the counterpart without mesostructure. Moreover, the Pt dispersion was improved due to mesoporosity. The highly dispersed Pt nanoparticles were beneficial for catalytic combustion of o-xylene. Futhermore, Pt/hierarchical ZSM-5 showed the efficient bi-functional performance during adsorption/catalytic combustion cycling process for o-xylene. Carbon balance was kept for three cycles without secondary pollutants, showing higher adsorption capacity and better reusing stability.

Visible-light-driven photocatalyst BiVO4 was synthesized via a facile microwave-hydrothermal method using BiVO3·5H2O and NH4VO3 as raw materials. Crystal structure of BiVO4 photocatalyst could be selectively controlled to be tetragonal or monoclinic by simply adjusting the pH of the precursor solution. The prepared samples were characterized by XRD, UV-Vis, Raman, and SEM. The mechanism of BiVO4 formation with different crystal structures was discussed. Meanwhile, the photocatalytic performances of the prepared sample were evaluated by degradation of methylene blue and photocalytic oxidation of NO gas in air under visible light irradiation. The results showed that BiVO4(z-t) microsphere was obtained when the precursor pH is 3-5, but when the pH is less than 2 or greater than 7, the as-prepared powders are BiVO4(s-m) with polyhedron morphology. This may be due to the change of pH that could form transformation of vanadate and bismuth ion in the precursor solution, and then affect the formation process of BiVO4, resuting in the change of crystal structure, morphology, crystal surface, and VO4 tetrahedron of BiVO4(s-m). The photocatalytic tests indicated that the activity of BiVO4(s-m) was much better than that of BiVO4(z-t). The BiVO4(s-m) sample prepared at pH 9 exhibits excellent visible-light photocatalytic activity, because of its higher crystalline, preferentially exposed facts (040), and higher degree distortion of VO43- tetrahedron.

Antireflective (AR) coatings, which can suppress the undesired interfacial Fresnel reflections, are widely used in optical devices and energy-related instruments. Conventional single-layer quarter-wave AR coatings, which only work at a single wavelength, have been seriously limited in some practical applications because of this inherent property. In this work, broadband AR coatings were designed and prepared based on the concept of λ/4-λ/2 double-layer interference film by Sol-Gel dip-coating method. Substrates (K9 glasses) coated with the double-layer films attained consistent high transmittances at 500-700 nm with an average transmittance of 99.4%, and the average transmittance at visible region was 99.0%. The λ/4-λ/2 broadband antireflective coatings were achieved without low-refractive- index materials. So high-refractive-index TiO2 could be introduced into the double-layer films to endow the films with self-cleaning property. The double-layer films exhibited outstanding superhydrophilicity with water contact angle of 2.2° in 0.5 s, and the superhydrophilicity lasted for 20 d in the absence of UV illumination. The double-layer coatings also showed a good ability to decompose organic substances under UV irradiation. The broadband of AR coatings with photocatalysis and durable superhydrophilicity may be applied in the fields of opto- and microelectronics.

A novel rice-like copper oxide (CuO) was synthesized without using soft template and alkali by hydrothermal and in-situ decomposition methods. This rice-like CuO material was made into the chemically modified electrode (CME) with Nafion solution for non-enzymatic glucose sensing. Structure and morphology of the prepared material and electrode were characterized by X-ray diffraction and scanning electron microscopy. Electrochemical performances of the obtained electrodes were investigated by linear sweep voltammetry, cyclic voltammetry, amperometric response, and electrochemical impedance spectroscopy. Results show that morphology of the obtained CuO particle is similar to rice grain. And its length and diameter are between 0.5-1.0 μm and 250-320 nm, respectively. The CME with 0.35 mg rice-like CuO (with 0.22 cm2 electrode surface area) has an obvious current response for glucose with the linear range from 0.0357 to 2.361 mmol/L, the linear equation Ipa(mA)= -0.00187+0.05239 c(mmol/L) (R2=0.998), the detection limit 0.0647 μmol/L, and the sensitivity 950.36 μA·L/(mmol·cm2). Therefore, the prepared CuO CME shows a promise selectivity and reliability for detecting glucose.

Polyaniline-carbon pillared graphene composites (PGR) were successfully prepared by vacuum extraction induced self-assembly and pyrolysis method. Effects of the mass ratio of aniline monomer (AN) and graphene oxide (GO) on structure and electrochemical properties of PGR were investigated by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and electrochemical characterization. Results showed that the polyaniline-carbon pillars uniformly distributed between the graphene (GR) layers to form a three-dimensional conductive network with expanded interlayer space and nitrogen doping, which effectively improved the structural stability and electrochemical performance of GR. The as-prepared PGR with the mass ratio of AN and GO at 1 : 1 exhibits a high reversible capacity of 653 mAh/g at a current density of 100 mA/g and an excellent rate capability of 343 mAh/g at a current density of 1 A/g, all that is much higher than that of the GR electrode (101 mAh/g).

Ag2Se quantum dots (QDs) was synthesized by co-deposition method which was further applied as co-sensitizer in solid-state dye-sensitized solar cells (DSSCs). The effects of different sensitization methods of Ag2Se QDs (TiO2/N719/QDs, TiO2/QDs/N719) and sensitization time (0-5 h) on the performance of QDs/dye co-sensitized solar cells were studied. Structure and optical properties of Ag2Se QDs were characterized by transmission electron microscopy (TEM) and ultraviolet-visible spectroscopy (UV-Vis). Furthermore, the transmission of charge carriers of solar cell devices was characterized by photo-modulated photocurrent/voltage spectrum (IMPS/VS) and electrochemical impedance spectra (EIS). It was found that the device with TiO2/QDs/N719 showed higher incident photon-to-current efficiency (IPCE) and photoelectric efficiency than those of TiO2/N719/QDs, which was due to the fact that TiO2/QDs/N719 photoanode adsorbed more QDs and dyes. With the extension of Ag2Se QDs sensitization time, the photovoltaic properties of DSSCs firstly ascended and then descended, achieving the highest photoelectric conversion efficiency 3.97%. The incorporation of Ag2Se QDs could effectively promote the electron transport and inhibit the electron-hole recombination, which benefited from a blocking layer that QDs served in device. As sensitization time prolonged over 2 h, the photovoltaic performances of device deteriorated, which was attributed to the augmented trap sites in Ag2Se QDs layer.

Traditional NiCo2S4 vulcanization process requires high-temperature and high energy supply, and has disadvantage of low conductivity. In this study, an environmental friendly vulanization method was utilized to prepare unique NiCo2S4@ACF core-shell heterstructure materials with activated carbon fiber (ACF) as skeleton at room temperature. NiCo2S4@ACF composite electrode material owns layered structures, which can effectively expand contact area with electrolyte, improve electron transmission path, and better create electrochemical performance. Specific capacitance of NiCo2S4@ACF composite electrode materials reached 1541.6 F/g (678 μF/cm2) at the current density of 1 A/g. In addition, the asymmetric supercapacitors (ASC) device fabricated with NiCo2S4@ACF as positive electrode and ACF as negative electrode exhibited energy density as high as 49.38 Wh/kg at the power density of 800 W/kg, and preeminent cycle stability up to 90.28% after 2000 cycles. All these data demonstrated that NiCo2S4@ACF is a promising potential application in the field of high-performance supercapacitors in the future.

NiCo2O4 nanomaterials exhibit great potential in the fields of energy storage and conversion especially in supercapacitors for their unique physicochemical properties. Given the important impact of morphology of nano material on its performance, this review focuses on preparation methods and application of NiCo2O4 nanostructure with various morphologies including nanoneedle, nanowire, nanotube, nanosheet, sphere, nanoflower, coral-like structure and three-dimensional hybrid structure. Furthermore, the influence of morphology and particle size of NiCo2O4 on its properties is also introduced. Finally, the future research direction of NiCo2O4 nanomaterials in the fields of energy storage and conversion is prospected.

As a type of novel thin film solar cells, perovskite solar cells develope sharply within a decade, which efficiency has approached to that of the commercial silicon solar cells. However, its poor stability in the air has limited the further practical application. Herein, we achieve uniform sable perovskite films under open environment by adding some poly 4-vinylpyridine (PVP). The morphology, structure and performance test results show that the perovskite films added with PVP were more compact and uniform than the bare one. Moreover, the assembled solar cell with 0.4wt% PVP exhibited highly reproducible efficiencies up to 13.07%, much higher than that of 6.09% for the controlled one. When restored in the air with approximately 50% relative humidity in the absence of encapsulation, its efficiency decay time to a half from 3 d for bare one extended to 3 w. However, high PVP additives result in incomplete reaction between PbI2 and CH3NH3I. If the above mentioned process is further optimized, is expected to be applied to the large-scale preparation of more stable perovskite film.

The stripping current arising from the oxidation of Cd was related to the concentration of Cd2+ in the sample. This study presents the determination of Cd(II) at low concentration μg/L levels by square wave anodic stripping voltammetry (SWASV) on an activated bismuth-film electrode (BFE). The electrode was initially modified by an electrochemical method, and then the electrodeposited bismuth-film was prepared again to improve the electrode, thereby enhancing the sensitivity to trace amounts of target Cd2+. The surface of glassy carbon electrode (GCE) before and after modification was characterizad by SEM, CV, EIS, and SWV. The parameters for the determination of the Cd2+ were investigated with the view of its application toward real samples containing low concentrations of Cd2+. Using the selected conditions, the limit of detection is 1 μg/L for Cd2+ at a preconcentration time of 10 min.

Given the good electrochemical performance and excellent irradiation stability of two dimensional transition metal carbides (MXenes), the development of MXene-based electrode materials for radionuclide detection is very promising. In this work, Ti3C2Tx MXene was activated via an alkalization strategy to form K+ intercalated Ti3C2Tx (K-Ti3C2Tx). Then the modified electrode of K-Ti3C2Tx/GCE was prepared on glassy carbon electrode (GCE). Ti3C2Tx and K-Ti3C2Tx were characterized by XRD, SEM and XPS techniques, and the electrochemical detection performance of K-Ti3C2Tx/GCE for trace uranyl ion (UO22+) was further investigated. Cyclic voltammetry (CV) experiments showed that the electrochemical response of K-Ti3C2Tx/GCE modified electrode to UO22+ increased significantly. Under the differential pulse voltammetry (DPV) scanning at pH 4.0, the K-Ti3C2Tx/GCE modified electrode presented a good linear detection relationship for UO22+ in the uranium concentration range of 0.5-10mg/L. The detection limit of this method is 0.083 mg/L (S/N = 3), with decent stability and repeatability.

It’s essential to develop patterning deposition methods to simplify the process of device fabrication and then reduce the production cost. In this work, a new patterning deposition method, i.e. microfluidic method, was demonstrated in details. In this technology, a micro-fluidic channel with a width of 80 μm and a height of 2 μm can be constructed between PDMS modules and substrates, and under capillary force precursor drops will move through the channel to form a patterned liquid film which is then fixed on the substrate via thermal treatments, and finally patterned films are prepared. In addition, the thermal-driven solidification process from NiOx precursor powder to oxide was investigated through thermogravimetric/differential thermal analysis (TG-DTA) measurement. And the evolution of phase structure of the NiOx precursor powder was analyzed with respect to post-annealing temperatures. Finally, thin-film transistors were fabricated applying the patterned NiOx thin films as channels, and the optimized device showed typical p-type transistor features, with a field-effect mobility up to 0.8 cm2·V-1·s-1.

All inorganic perovskite (CsPbX3) nanocrystals has wide applications in the field of optoelectronic devices due to its excellent photoelectric characteristics, however, stability is still the bottleneck restricting its development. Combining with the current research progress, the BN/CsPbX3 composite nanocrystals phosphors was synthesized via all-solid-state reactions. During the process, parameters of ball milling, ratio of reactants and other reaction conditions were optimized, thus the BN/CsPbX3 composite nanocrystals can be stable in the air for more than 60 days. Its luminescence wavelength can cover the range of 417-680 nm with full width at half maximum of 23-47 nm, showing high color purity, and was further used in white LED with high stability and luminance. After placed in the atmosphere for a month, the attenuation of LED luminance is only about 0.7%, and less than 4% deterioration was observed after continuous work of 2 h, showing great working stability.

As a perovskite family member, SrTiO3 shows significant applications in the fields of solar cells, photocatalysis, fuel cells and superconducting as a dependence of its crystallinity, morphology, crystal facet and optical properties. In this work, we reported an in-situ synthetic approach of SrTiO3 nanostructures with modified morphology and tunable optical absorption properties based on conventional plasma electrolytic oxidation (PEO) associated with hydrothermal method. The morphology of SrTiO3 nanostructures can be selectively modified from microcubes with smooth facets to ultrathin nanosheets by controlling the concentration of Sr source during PEO process. It is found that both SrTiO3 microcubes and Sr1-δTiO3 nanosheets are well-crystallized single crystals. UV-Vis diffuse reactance spectrum (DRS) measurement reveals that Sr1-δTiO3 nanosheets with thin thickness show obvious blue-shift of absorption edge in comparison with SrTiO3 microcubes due to the size effect. Finally, the morphology evolution and nucleation mechanism of SrTiO3 nanostructures in-situ grown on PEO film is discussed.

Using Ti3AlC2 as the precursor, a new MAX phase Ti3ZnC2 was synthesized via an A-elemental substitution reaction in a molten salts bath. Composition and crystal structure of Ti3ZnC2 were confirmed by XRD, SEM and TEM analysis. Its structure stability and lattice parameter of Ti3ZnC2 were further proved by a theoretical calculation based on density function theory (DFT). Moreover, thermodynamics of A-elemental substitution reactions based on Fe, Co, Ni, and Cu were investigated. All results indicated that the similar substitution reactions are feasible to form series of MAX phases whose A sites are Fe, Co, Ni, and Cu elements. The substitution reaction was achieved by diffusion of Zn atoms into A-layers of Ti3AlC2, which requires Al-Zn eutectic formation at high temperatures. The molten salts provided a moderate environment for substitution reaction and accelerated reaction dynamics. The major advantage of this substitution reaction is that MAX phase keeps individual metal carbide layers intact, thus the formation of competitive phases, such as MA alloys, was avoided. The proposed A-elemental substitution reactions approach opens a new door to design and synthesize novel MAX phases which could not be synthesized by the traditional methods.

As the continuous development of the photovoltaic industry and the flat panel display devices, the demand for transparent electrodes is increasing rapidly. The most commonly used transparent conductive material, ITO, was criticized for its brittleness, which limited its application in the up-and-coming market. Cu nanowire transparent electrodes acts as promising candidate for the new generation of transparent electrodes due to their superior conductivity, low cost, easy accessibility and high flexibility. The synthesis of Cu nanowires and their application in transparent electrodes has drawn lots of attention. Progresses have been made in recent years. A comprehensive elaboration of the controllable synthesis of Cu nanowires through liquid synthesis methods and the mechanism behind them, the fabrication and post-treatment methods of Cu nanowire electrodes, the application of Cu nanowire electrodes in photovoltaic devices, transparent heaters and flexible devices are given. The trends of Cu nanowire electrodes is proposed.

All-inorganic cesium lead halide CsPbX3 (X = Cl, Br, I) perovskite materials emerged as a rising star in the area of optoelectronics since 2015, due to its excellent photoelectric properties and environmental stability. Substantial progresses were made in the application of many electronic and optoelectronic devices, which attracted wide attention from the scientific community. This paper mainly reviews the latest research progress of cesium lead halide perovskite based planar heterojunction LED, where the structure and working principle of LED devices are briefly introduced. In addition, the classification and summarization of some optimization strategies for improving luminescence performance and working stability of LED devices are emphatically suggested, and the development trend of stable and efficient inorganic perovskite based planar heterojunction LED is finally prospected.

The technique for Materials Genetic Initiative (MGI) is the key tool for realizing the demand-oriented design of new materials assisted by the artificial intelligence (AI). Accordingly, the development and application of innovative intelligence algorithms are particularly important. Based on the generalization and analyses of the existing nature-inspired algorithms, this work aims at outlining the suggestion to build the nature-inspired algorithms library (NIAL). The potential route in which inspirations are obtained from varieties of disciplines, was used to produce new algorithms in high-throughput ways is introduced. The general procedure for building algorithm library is elaborated, while its advantages and characteristics are anatomized. Finally, the potential of NIAL in new materials development has been envisioned to enhance the standard for the application of AI including MGI.

With the development of nuclear energy, the long-lived radionuclides are inevitably released into the natural environment during the mine process, fuel manufacture, nuclear power usable and spent fuel management, which are dangerous to human health and environmental pollution. Thereby the efficient elimination of radionuclides is an important parameter which affects the development of nuclear power. In recent years, the metal-organic frameworks (MOFs) have attracted worldwide attention in the adsorption of radionuclides from large volume of aqueous solutions, because of their high chemical stability, abundant functional groups and changeable porous structures. In this review, we mainly summarized the recent works of MOFs in the efficient removal of radionuclides, and to understand the interaction mechanism from batch adsorption experiments, model analysis, advanced spectroscopy analysis, and theoretical calculation. The adsorption capacities of MOFs with other materials were also summarized, and the future research opportunities and challenges are given in the perspective.

Respiratory frequency and mode could be applied for medical diagnosis and health evaluation. Traditional medical diagnosing devices have bulky size and high cost, and are of inconvenience in use. To fulfill the urgent demand for high-performance, low-cost, and portable electronic devices, this study proposes to fabricate self-powered planar humidity sensors by inkjet-printing method by virtue of the characteristics that graphene oxide self-polarizes and is sensitive to humidity. This sensor linearly responds to the relative humidity, and both responds and recovers rapidly. In addition, this sensor possesses excellent sensitivity and stability after multiple cycling and long-term storage, and has realized monitoring of the respiratory frequency and mode. The humidity sensors in this work is ready to fabricate with low production cost, free from interference by body motion or exterior environment, and suitable for real-time monitoring respiratory frequency and mode.

To achieve effective load of black TiO2 nanoparticles and improve the practical application ability, the pulsed laser spraying was proposed. The composite coating was prepared on quartz glass substrate, which consisted of amorphous molecular sieve and rutile TiO2 nanocrystals. The surface morphology of the composite coating was characterized, and a series of test about composite coating powder was conducted including absorption properties, phase structure, chemical valence, and photocatalytic properties. The results show that the coating is porous structure packed with 2-5 μm ball and has strong absorptive capacity in the visible region. In the process of pulsed laser sputtering, the molecular sieve changed to amorphous structure, and TiO2 changed from anatase to rutile type. Ti4+ ion was reduced to Ti3+ ion, which resulted in reduced band-gap. The pulsed laser spraying technology achieves the fast load of the black nano TiO2, which still has good photocatalytic ability under the full spectrum and visible light conditions.

Fe, N doped 2D porous carbon catalyst was synthesized by pyrolysizing the precursor, ZIF-8, on graphene. Meanwhile, Fe-2,2-bipy were coordinated on ZIF-8. The catalyst was analyzed by SEM, XRD, and XPS for morphology, structure and component. The ORR and OER performance of the Fe, N doped 2D porous carbon catalyst were characterized by RDE, CV curves and LSV curves. It was found that the Fe, N doped 2 D porous carbon catalyst shows uniform 2D structure and that the content of Fe element is 1.32%. The catalyst shows 0.83 V half-wave potentials for oxygen reduction reaction (ORR) in 0.1 mol/L KOH solution and 420 mV over-potential for oxygen evolution reaction (OER) at 10 mA/cm2 in 1 mol/L KOH solution. Then, a zinc-air battery was assembled using as-synthesized catalyst. The power density of zinc-air battery is up to 245 mV/cm2. Furthermore, it shows superior cycling stability.

Two dimensional (2D) materials have attracted wide attention due to their ultrathin atomic structure, large specific surface area and quantum confinement effect which are remarkably different from their bulk counterparts. Anisotropic materials are unique among reported 2D materials. Their orientation-dependent physical and chemical properties make it possible to selectively improve the performance of materials. As representative examples, Re-based transition metal dichalcogenides (Re-TMDs) have tunable bandgaps in visible spectrum, extremely weak interlayer coupling, and anisotropic properties in optics and electronics, which make them attractive in the application areas of electronics and optoelectronics. In this riviev, the unique crystal structures and intrinsic properties of the Re-based TMDs semiconductors are introduced firstly, and then the synthetic method is introduced, followed by discussion on the unique physical characterizations and optimized means. Finally, prospects and suggestions are put forward for the preparation and research of ReX2.