There are similarities between the growth processes of ingot crystalline silicon with different sizes, so the growth law of small size crystals could be transferred to large size crystals. In this paper, transfer learning (TL) was used to design the hot zone of the G8 ingot furnace. The design targeted parameters are the positions and volumes of the side and top heaters, and the height of the partition block on the side insulation cage. The main design goals are to reduce the dislocation defects inside the crystal, suppress polycrystalline at the edge of the silicon ingot and make the solid-liquid interface slightly convex. First, a neural network was used to establish a mapping model between the hot zone geometric parameters and hot zone evaluation parameters for the existing G7 ingot furnace. Then the model was transferred to the G8 ingot furnace. The effects of different model structures on the transfer process were analyzed. Then Dropout was used to determine whether the model is overfitting. The genetic algorithm (GA) and the clustering algorithm (CA) were applied to optimize the hot zone geometric parameters. The above is the process of G8 hot zone design. Finally, the numerical simulation method was used to study the temperature distribution and solid-liquid interface shape of the optimized schemes. The final selected scheme could achieve high quality crystal growth. Then the scheme was applied to the hot zones of G7 and G8 furnaces. The results show that the axial temperature gradient of G8 in silicon melt and silicon crystal is smaller than that of G7, and the radial temperature gradient at the solid-liquid interface is also smaller than that of G7. It is beneficial to reduce the thermal stress inside the crystal.

25.4 mm diameter crystals of CeBr3 and three analogues doped with 0.1%, 0.2% and 0.5% of Sr2+in molar ratio were grown by the vertical Bridgman method. The grown crystals were processed into 25.4 mm diameter wafer with a thickness of 10 mm and characterized by fluorescence spectra excited by UV light and X-ray as well as multi-channel analysis with 137Cs source. Results show that the emission bands of the crystals under X-ray excitation are slightly red-shifted by Sr2+ doping, and with the increase of Sr2+ doping content, the energy resolution of the crystals are successively improved, while the light yield are gradually reduced. The CeBr3 crystal doped with 0.5%Sr2+ exhibits the best energy resolution of 3.83%@662 keV. However, high Sr2+doping also causes difficulty in crystal growth. A doping content of 0.2% is considered appropriate with regards to both scintillation property and crystal growth availability. An encapsulated CeBr3∶0.2%Sr crystal with dimension of 25.4 mm×25.4 mm is obtained and the energy resolution is 3.92%@662 keV.

The concave corner structure has excellent vibration and noise reduction characteristics to effectively attenuate the structural vibration response, honeycomb structure with excellent mechanical properties has been more commonly used in engineering, so the composite structure of concave corner honeycomb has attracted the attention of scholars. A novel phononic crystal model was created using the inner concave honeycomb structure’s fractal design. Based on the finite element method, the fractal concave angle honeycomb structure was analyzed to calculate the energy band structure and vibration transmission characteristics, as well as to examine the negative Poisson ratio characteristics of the structure and the effect of the structural fractal on the vibration band gap. By varying parameters such as wall thickness and the angle of the inner concavity, filling the steel at the apex of the fractal structure can provide better suppression of certain frequency bands of vibration. The results show that the fractal structure still has negative Poisson ratio characteristics, the fractal structure produces a wider band gap in the second-order structure, the increase in wall thickness and concave angle causes the structural vibration band gap to shift to the high-frequency region, the filled steel causes the band gap to widen.

Cr-doped Ga2O3(Ga2O3∶Cr) thin films were deposited on sapphire (α-Al2O3) substrates by dual-target RF magnetron co-sputtering at different oxygen flow rates. Structures and optical properties of the deposited Ga2O3∶Cr thin films were investigated in detail before and after annealing at 900 ℃. The results clearly reveal that the deposited Ga2O3∶Cr thin films are amorphous, and their luminescence mainly appear in the blue-green band. The structures transform from amorphous into polycrystalline after 900 ℃ annealing, and near-infrared luminescence band originated from the doping Cr3+ is well observed. Both the crystalline quality and near-infrared luminescence intensity of the annealed films show strong dependence on oxygen flow rates, while their optical band gaps keep almost unchanged. Moreover, in the range of oxygen flow rates, it has been demonstrated that the Ga2O3∶Cr thin film with the strongest near-infrared luminescence intensity could be obtained under the oxygen flow rate of 4 mL/min. In such case, the obtained film has the better crystalline quality and the amount of Cr3+ substituted Ga3+ is relatively large. This findings could be helpful for preparing Ga2O3∶Cr thin films with better quality.

In this study, manganese-cobalt-nickel-oxide (Mn-Co-Ni-O, MCNO) thin films were prepared on silicon substrates by radio frequency (RF) magnetron sputtering and post-annealing. The crystal structure and surface morphology of the thin films were characterized by X-ray diffraction and scanning electron microscopy, and their optical properties were tested and analyzed by optical testing instruments. The effect of RF sputtering power (60~100 W) on the surface morphology, crystal structure and optical properties of MCNO thin films were analyzed. The surfaces of the films obtained under 60~90 W were dense and uniform, but the surface grain size of the MCNO thin films obtained under 100 W increases significantly. The phase analysis shows that the MCNO thin films deposited by RF magnetron sputtering are mainly spinel structures, and the sputtering power has a significant effect on the crystal quality and preferred orientation of thin films. The crystal quality of the MCNO thin films obtained under 80 W is the best. At the same time, the Raman spectroscopy test also shows that the MCNO thin film exhibits the strongest Mn4+-O symmetrical bending vibration and the smallest compressive stress. Ultraviolet-visible-near-infrared spectroscopy analysis show that the absorption range of MCNO thin films is mainly in the visible-near-infrared band, and the MCNO thin films obtained under the sputtering power of 80~90 W show stronger absorption peaks in the near-infrared band. The change of the RF sputtering power can affect the thickness and crystalline quality of the thin film, thereby regulating the optical band gap of the thin film. The luminescence of the defect peaks at different sputtering powers was measured by photoluminescence spectroscopy, and the thin films deposited at 80 W have the strongest UV emission peaks, demonstrating that varying the sputtering power can effectively improve the defects and crystal quality.

Metal-organic frameworks (MOFs) have become a hotspot because of their unique structures and potential applications in the field of crystal engineering and material science. At present, most metal centers of MOFs are transition metals, while the group Ⅱ metals (alkaline earth metals) with special configurations have obtained relatively less attention. In this work, a novel three-dimensional (3D) Ba(Ⅱ)-MOF, ［Ba(INO)2］n was synthesized by solvothermal method, with isonicotinic acid N-oxide (HINO) as organic ligand and barium chloride dihydrate (BaCl2·2H2O) as metal salt. The structure and properties of this Ba-MOF were characterized by single crystal X-ray diffraction, X-ray powder diffraction, infrared spectroscopy, elemental analysis, thermogravimetric analysis and fluorescence spectroscopy. Single crystal X-ray diffraction results show that ［Ba(INO)2］n crystallizes in the monoclinic Cc space group, and the unit cell parameters a=1.636 14 (7) nm, b=1.126 35 (4) nm, c=0.742 40 (3) nm. The Ba(Ⅱ) center is nine-coordinated distorted three cap triangular prism geometry. The Ba-O one-dimensional (1D) chains in ［Ba(INO)2］n are connected by type-B INO ligands to form a two-dimensional (2D) layer, and then extended by type-A INO ligands along four directions to form a 3D framework. However, interestingly, when the Ba-O 1D chains are directly connected by type-A INO ligands, a 3D microporous framework can be formed, while type-B INO ligands further support the 3D framework to form a solid and stable pillared structure. ［Ba(INO)2］n shows good thermal stability. In addition, the solid-state fluorescence test shows that,［Ba(INO)2］n exhibits a maximum emission peak at 395 nm under the excitation of 330 nm ultraviolet light. It shows an obvious blue shift compared to the 437 nm maximum emission peak of HINO ligand, which is caused by the electronic transition between INO ligand and Ba(Ⅱ) metal center.

In view of the problem that the photoelectric conversion efficiency of P-type passivated emitter rear contact (PERC) solar cells reduces due to the influence of potential induced degradation and damp-heat degradation during the service period, the degraded solar cells were recovered by photo & electric injection and thermal annealing process. In the meantime, the efficiency improvement mechanism was studied. The experimental results show that 94.32% of degraded solar cells are recovered successfully, and the average photoelectric conversion efficiency of all investigated cells is increased by 8.96%, under the optimal experimental conditions of 3 times standard sunlight intensity, 10 A of electric injection current, 150 ℃ of annealing temperature, and 50 min of processing. The results of photoluminescence spectra and quantum efficiency show that the photoelectric injection and thermal annealing can effectively reduce the internal and rear surface defects of silicon substrate caused by potential induced degradation and damp-heat degradation, and the photoelectric conversion efficiency of degraded solar cells can be finally improved.

All-inorganic perovskite solar cells (PSCs) have gained significant attention due to their excellent photoelectric conversion efficiency and high stability. However, Pb-based perovskites are easily decomposed into toxic Pb compounds and are fatal to environment, which limit their further application. Despite the great effort carried out to substitute the Pb by a less hazardous element, lead-free perovskites still remain more unstable than lead-containing perovskites, and present lower performance as well. In this paper, Sn is used to partially replace Pb for obtaining all-inorganic tin-lead perovskite thin film, and salicylic acid is added for inhibiting the oxidation of Sn2+ to Sn4+, so as to achieve the goal of improving photoelectric conversion efficiency cells by a stable phase. The experimental results show that the photoelectric conversion efficiency of the device increases first and then decreases with the increase of the amount of salicylic acid from 2 mg·mL-1 to 6 mg·mL-1. Through the tests of SEM, XRD, XPS, it is found that the phase stability of the film is the best when the content of salicylic acid is 4 mg·mL-1. Compared with the device without salicylic acid, the short-circuit current density (Jsc) increases from 14.7 mA·cm-2 to 15.1 mA·cm-2significantly, meanwhile, the photoelectric conversion efficiency increases from 5.8% to 6.5%. In addition, the initial photoelectric conversion efficiency of the best device can still maintain 50% of the original efficiency after 5 d of storage in the air environment, which further proves that the addition of salicylic acid has a certain role in promoting the stability of tin-lead perovskite phase.

In this study, the crystallization process of type-α hemihydrate calcium sulfate (α-HH) in the hemihydrate wet-process phosphoric acid production was simulated. The crystallization induction time of α-HH was determined by monitoring the turbidity changes in 95 ℃, supersaturation from 1.64 to 2.10, 30%P2O5 phosphoric acid solution with different F- and SiF2-6 concentration. The critical nucleation radius and nucleation rates of α-HH were calculated by classical nucleation theory equations, and the effects of F- and SiF2-6 on the crystallization process of α-HH were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results show that with the increase of F- and SiF2-6 concentration, the crystallization induction time, the surface energy, and the critical nucleation radius of α-HH crystals increase, but the nucleation rates of α-HH crystals decrease. When 0.06 mol·L-1 F- is introduced in the system at the supersaturation 1.64, the crystallization induction time of α-HH crystals is prolonged by 465 s and the nucleation rate is reduced to 0.403×1029 crystal nuclei·cm-3·s-1. However, in the presence of 0.06 mol·L-1 SiF2-6, the crystallization induction time of α-HH crystals is prolonged by 710 s, and the nucleation rate is reduced to 0.339×1029 crystal nuclei·cm-3·s-1. The effect of SiF2-6 on nucleation inhibition of α-HH crystals is greater than that of F-. The F- and SiF2-6 hinder the growth of α-HH crystals along the C-axis, resulting in a decrease of the crystal aspect ratio and a change of the crystal morphology to short cylinder shape. F- and SiF2-6 affect the intensity and crystallinity of α-HH crystals (200), (310), (400) crystal planes. The concentration levels of F- and SiF2-6 in the semi-aqueous wet phosphoric acid are controlled to obtain short columnar α-HH crystals, which are favorable for filtration and washing.

The introduction of hydrogen energy can effectively improve the power supply reliability of the distribution network, and hydrogen production from water electrolysis is a key technology to achieve low-carbon transformation, so it is imperative to develop efficient electrolysis water catalysts. Transition metal oxides have large reserves and high catalytic activity, and are regarded as promising oxygen evolution reaction catalysts. In this work, the oxygen evolution catalyst of graphene which supports Co3O4 was prepared by radio frequency plasma. The test results of XRD, Raman and XPS show that the introduction of two-dimensional graphene accelerates the surface electron migration and increases the reaction area. Plasma treatment facilitates the loading of nanoparticle on graphene, and plasma etching is used on the surface of catalyst to create a large number of graphene structural defects and oxygen vacancies, which improves the distribution of active sites, effectively regulates the electronic structure of Co3O4 and improves the catalytic activity of oxygen evolution. Electrochemical tests show that the overpotential of Co3O4@rGO synthesized in this experiment is 410 mV at a current density of 50 mA·cm-2, the kinetic reaction rate is fast, and exhibits a catalytic activity of oxygen evolution that is superior to that of commercial IrO2.

Phosphorus-doped mesoporous carbons (PMCs) were synthesized by solvent evaporation-induced self-assembly (EISA) method using phenolic resin as carbon precursor, phosphoric acid as phosphorus source, and the triblock copolymer F127 as soft template. The morphology and structure of the prepared PMCs were characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The electrochemical properties of samples were tested by electrochemical workstation. The results show that phosphorus mainly exists in the form of C-P bond and P-O bond in mesoporous carbon. Electrochemical tests show that the maximum specific capacitance can be obtained by adjusting the amount of phosphorus doping. When the current density is 0.5 A/g, the specific capacity of mesoporous carbon is 140 F/g, while the optimized mesoporous carbon reaches 176 F/g.

The CuAl1-xMgxO2 (x=0, 0.005, 0.01, 0.02, 0.03, 0.04) polycrystals with delafossite structure were prepared by solid state reaction. The effects of Mg doping on structure and properties of CuAlO2 polycrystals were studied. With the Mg doping amount x increasing from 0 to 0.02, the samples are of rhombohedral single phase with the space group of R3m, and density increases gradually. All samples exhibit the thermally activated electrical transport behavior of semiconductor, for x=0.02 sample, the room temperature resistivity is 1/19 of undoped sample, and the thermal activation energy decreases significantly (x=0, ρ300 K ~5.54 Ω·m， Ea~0.328 eV; x=0.02, ρ300 K~0.29 Ω·m, Ea~0.218 eV), the carrier concentration increased by 1 order of magnitude, as a result of the Al3+ is substituted by Mg2+, the new acceptor energy level is introduced. When x is greater than 0.02, the impurity phase of spinel MgAl2O4 increases, which leads to the drop of electrical conductivity and thermal conductivity. The lattice thermal conductivities of CuAl1-xMgxO2 polycrystals are absolutely dominant in total thermal conductivity, and decrease as the temperature (300~500 K) increases. The simulation results of the Callaway model demonstrate that the point defect-phonon scattering makes a major contribution to thermal resistance of all samples. Compared with x=0, the room temperature thermal conductivity is doubled (κ~13.065 0 W/(m·K)), while the sound velocity increases and the point defect-phonon scattering weakens when x=0.02. The analysis shows that the strong Mg-O bond is formed by Mg-doping, which improves the elastic modulus of crystal and the phonon frequency, while the scattering between point defects and phonon is weakenes, the point defects include intrinsic point defect, the mass fluctuation and strain field fluctuation caused by Mg doping. The increase of density by Mg doping is also beneficial for thermal conductivity.

For the nonlinear equations of thickness-shear vibration and flexural vibration of quartz crystal plate considering geometric and material nonlinearity, the equations are transformed and solved by the newly proposed extended Galerkin method. The strongly coupled frequency-response relationships of thickness-shear and flexural vibrations of quartz crystal plate are obtained respectively, and the frequency-response curves under the influence of different amplitude ratios and different driving voltages are drawn. The numerical results show that the optimal aspect ratio size of quartz wafer should be selected to avoid the strong coupling of the two modes. The change of driving voltage will cause the obvious change of thickness-shear vibration frequency of quartz crystal resonator. The frequency shift value must be controlled within the allowable value of common piezoelectric acoustic devices. The solution of high frequency nonlinear vibration equations of quartz crystal plate by extended Galerkin method lays a foundation for nonlinear finite element analysis and partial field effect analysis.

Electron backscattering diffraction (EBSD) patterns reveal information about the phase component, crystal structure, grain orientation, grain size and grain boundaries of the material. EBSD patterns are very complex and usually require special computing software to analyze. A systematic study of the mathematical characteristics of EBSD patterns is carried out in this paper. A mathematical relationship between arbitrary crystal orientation and EBSD pattern is established, mathematical characteristics of EBSD patterns at pattern center of the basal zone axes of face-centered cubic, body-centered cubic, and close-packed hexagonal crystals are derived, as well as the theoretical Kikuchi patterns of (001) orientation and (001) orientation of face-centered cubic crystals. The theoretical EBSD pattern characteristics of the basic crystal zone axes of each lattice are compared in the analysis of the measured EBSD patterns, that is, by comparing the image features, the crystal system, lattice and the crystal zone axes ［uvw］ corresponding to the intersection points of some Kikuchi lines of the measured patterns can be directly determined. The crystal orientation or texture can be calculated from the coordinates of the basic crystal zone axes, and the spatial distribution of the basic crystal plane can also be provided, such as atomic close-packed plane in the sample, which is beneficial to the study on the deformation or growth mechanism of the crystal. EBSD provides new methods for single-crystal chip quality inspection.

Flower-like molybdenum disulfide was synthesized from molybdenum trioxide and sulfur by argon protection solid-state method. The structure and morphology of the products were characterized by XRD, SEM and TEM. The effects of raw material ratio, reaction temperature, reaction time and heating rate on the purity of the product were investigated, and molybdenum disulfide with high purity was prepared. The results show that when the molar ratio of MoO3∶S is 1∶7.5, the reaction temperature is 450 ℃ and the reaction time is 4 h, heating rate is 15 ℃/min, the flower-like molybdenum disulfide with purity of 99.4% can be obtained. The flower-like structure is composed of warped thin plate with thickness of about 10 nm. 0.62 nm monolayer MoS2 is observed by TEM. Flower-like molybdenum disulfide has large specific surface area, which has broad application prospects in the fields of energy storage and catalysis.

AlN powder was prepared by wet chemical method in NH3 atmosphere using aluminum chloride hexahydrate and urea as raw materials and methanol as solvent. The products were characterized by X-ray diffractometer, scanning electron microscope and laser particle size analyzer. The results show that hexagonal AlN powders with high purity are obtained when the calcination temperature is above 900 ℃. The product obtained at 1 000 ℃ presents spherical characteristics, whose average crystallite size and particle size are 17.0 nm and 159.5 nm. The microstructure of AlN powder was further characterized by high-resolution transmission electron microscope. Combined with selective electron diffraction and Raman spectroscopy, it is further confirmed that the amorphous impurities existing on the surface of AlN powders are not residual carbon generated in high temperature reducing atmosphere, but should be attributed to alumina hydroxide generated by hydrolysis on the surface of AlN powders.

The influence of complexing agent, solution pH value and temperature on the quality of electroless nickel plating of diamond powder at low temperature were investigated. At the temperature of 35 ℃ and the pH value of 5, the stability of plating solution, deposition rate, morphology and phosphorus (P) content of electroless nickel plating coating were tested and analyzed by changing the ratio of complexing agent. The results show that C6H8O7·H2O (20 g/L)+(CH2)2(COOH)2(5 g/L) is the best complexing agent in test samples. The electroless plating solution corresponding to the complexing agent has good stability and rapid deposition rate (0.391 5 g/h), and the obtained coating is leak-free and dense, with P weight content of 11.73%. The deposition rate, morphology and P content of electroless plating samples were measured and analyzed by changing pH value and temperature of plating solution with the best complexing agent. The results show that when the temperature of the plating bath is 35 ℃ and the pH value is 3~13, the deposition rate increases and the P content gradually decrease with the increase of the pH value. When the pH value is higher than 11, the rapid reaction rate is difficult to stabilize the pH value of the plating solution, and the plating solution is easy to decompose, so the pH value is more suitable within 5～11. The effect of temperature on plating was studied in the range of 30~50 ℃ at solution pH value of 5. It is found that the deposition rate and P content increase with the increase of temperature, and the plating layer is dense and leak-free. When the temperature is higher than 45 ℃, the reaction rate is too fast and it is not easy to stabilize the pH value of the plating solution, so the temperature is more appropriate in the range from 35 ℃ to 45 ℃.

In this paper, TiO2/g-C3N4 composite powder was prepared by electrostatic adsorption method, and its morphology, composition and optical properties were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), UV-Vis diffuse reflectometry (UV-Vis DRS) and other characterization methods. Rhodamine B was used as a simulated pollutant to characterize its photocatalytic performance under UV light. The result show that: in the Rhodamine B degradation experiment, when the loading amount of TiO2 reaches 15% (mass fraction), the composite powder has more obvious catalytic degradation effect, and the degradation efficiency can reach 99.40% within 20 min. After adding isopropanol as hydroxyl radical capture agent, the degradation rate decreases to 27.30%, and it is determined that the main active substance of the reaction is hydroxyl radical. Ultraviolet assisted Fenton reaction can obviously improve the effect of traditional Fenton reaction, and the reaction mechanism of catalyst was explored.

Nano-CaCO3 was prepared by liquid-phase precipitation using a micro-sieve reactor with Ca(NO3)2·4H2O as calcium source continuous phase and (NH4)2CO3 as carbon source dispersed phase. The effects of the preparation conditions such as flow rate, concentration and residence time of the dispersed and continuous phases on the particle size, yield and morphology of calcium carbonate were investigated by XRD and TEM. The results show that the calcite nano-CaCO3 prepared by liquid-phase precipitation in micro-sieve reactor has an average particle size from 45 nm to 92 nm and a yield of more than 80%. The suitable preparation conditions are:continuous phase feed flow FC=150 mL/min, dispersed phase feed flow FD=150 mL/min, continuous phase concentration ［Ca2+］=0.05 mol/L, dispersed phase concentration ［CO2-3］=0.2 mol/L and residence time τ=5 s. The unique pore structure of the micro-sieve reactor can evenly disperse the liquid-phase system, thus avoiding the clogging problem occuring in liquid-phase precipitation reactions in general micro reactors. The molecular diffusion and mixing mode of the micro-sieve reactor could homogeneously enhance the perturbation of the liquid phase system and increase the supersaturation of CaCO3, leading to smaller particle size with a very narrow distribution. Meanwhile, the shape and size of the samples can be flexibly adjusted by changing the preparation conditions.

Rutile Ti1-2xCrxMoxO2 (x=0, 0.05, 0.10, 0.15, 0.20) pigments were synthesized by solid-state reaction method with TiO2, Cr2O3 and MoO3 as the main raw materials. The effects of Cr/Mo co-doping amount and calcination temperature on the phase structure, color performance and microstructure of obtained Ti1-2xCrxMoxO2 pigments were investigated. The results show that the same amount of Cr/Mo co-doping of 5%~15% mole fraction led to single-phase rutile pigments of black color, which can promote the phase transformation from anatase to rutile. Furthermore, the introduction of Mo is beneficial for improving the solid solubility of Cr in TiO2 lattice. With the increase of Cr/Mo co-doping content, the blackness (L* value) of the sample decreases first and then increases, while the redness (a* value) and yellowness (b* value) both show an opposite trend. When the calcination temperature is 950~1 100 ℃, the change of chromatic parameters of the samples is relatively small. The Ti0.70Cr0.15Mo0.15O2 pigment calcined at 1 100 ℃ shows the best color performance of black, and its L*, a* and b* values are 24.41, 2.12 and -2.53, respectively. The obtained rutile pigments also have good color performance and chemical stability in ceramic glaze. The main mechanism to produce black color could be attributed to the lattice distortion of rutile TiO2 and charge defects caused by appropriate Cr/Mo co-doping, thus absorbing most visible light.

Two-dimensional (2D) materials are considered as the ideal materials for the next-generation information devices, owing to their nanoscale sizes, novel electronic properties, excellent mechanical properties, et al. In recent years, with the development and improvement of bottom-up preparation methods, such as epitaxial growth method, and material calculation methods, more and more two-dimensional materials with non-layered bulk phases have been prepared and discovered. Here, the research progresses of new two-dimensional group 11 (include Cu, Ag, Au) chalcogenides with non-layered bulk phases which show application potential in information devices and other fields are summarized. Taking stoichiometric ratio as the main line, the atomic structures and physical properties of monolayer MX (M=Cu, Ag, Au; X=O, S, Se, Te), M2X and other stoichiometric-ratio group 11 chalcogenides are introduced in detail from both experimental and theoretical perspectives. Two-dimensional group 11 chalcogenides possess not only all electronic properties (metal, semiconductor and insulator) but also abundant novel physical properties (superconductivity, topology, magnetism, etc.). Due to the novel properties and potential applications of the 2D group 11 chalcogenides, the novel class of 2D materials is worthy of more attention.