[1] S GUPTA, W KELLOGG, H XU et al. Bifunctional perovskite oxide catalysts for oxygen reduction and evolution in alkaline media. Chemistry-An Asian Journal, 11, 10-21(2016).

[2] M BAJDICH, M GARCIA-MOTA, A VOJVODIC et al. Theoretical investigation of the activity of cobalt oxides for the electrochemical oxidation of water. Journal of the American Chemical Society, 135, 13521-13530(2013).

[3] L ZHANG, M CHEN H, D WEI Z. Recent advance in transition metal oxide-based materials for oxygen evolution reaction electrocatalysts. CIESC Journal, 71, 3876-3904(2020).

[4] P ZHANG, F LU X, W NAI J et al. Construction of hierarchical Co-Fe oxyphosphide microtubes for electrocatalytic overall water splitting. Advanced Science, 6, 1900576(2019).

[5] G CHEN, P ZHU Y, M CHEN H et al. An amorphous nickel-iron- based electrocatalyst with unusual local structures for ultrafast oxygen evolution reaction. Advanced Materials, 31, 1900883(2019).

[6] H REN W, X TAN, F YANG W et al. Isolated diatomic Ni-Fe metal-nitrogen sites for synergistic electroreduction of CO₂. Angewandte Chemie International Edition, 58, 6972-6976(2019).

[7] J CHEN, W LIU J, Q XIE J et al. Co-Fe-P nanotubes electrocatalysts derived from metal-organic frameworks for efficient hydrogen evolution reaction under wide pH range. Nano Energy, 56, 225-233(2019).

[8] Z SUN F, G WANG, Q DING Y et al. NiFe-based metal-organic framework nanosheets directly supported on nickel foam acting as robust electrodes for electrochemical oxygen evolution reaction. Advanced Energy Materials, 8, 1800584(2018).

[9] L TAO, M QIAO, R JIN et al. Bridging the surface charge and catalytic activity of a defective carbon electrocatalyst. Angewandte Chemie, 131, 1031-1036(2019).

[10] P GAO X, Y ZHOU, Q LIU S et al. Single cobalt atom anchored on N-doped graphyne for boosting the overall water splitting. Applied Surface Science, 502, 144155(2020).

[11] J MAHMOOD, K LEE E, M JUNG et al. Nitrogenated holey two- dimensional structures. Nature Communications, 6, 1-7(2015).

[12] M DAI L, H XUE Y, T QU L et al. Metal-free catalysts for oxygen reduction reaction. Chemical Reviews, 115, 4823-4892(2015).

[13] Y ZHOU, P GAO G, Y LI et al. Transition-metal single atoms in nitrogen-doped graphenes as efficient active centers for water splitting: a theoretical study. Physical Chemistry Chemical Physics, 21, 3024-3032(2019).

[14] T SUEN N, F HUNG S, Q QUAN et al. Electrocatalysis for the oxygen evolution reaction: recent development and future perspectives. Chemical Society Reviews, 46, 337-365(2017).

[15] H MONTOYA J, C SEITZ L, P CHAKTHRANONT et al. Materials for solar fuels and chemicals. Nature Materials, 16, 70-81(2017).

[16] C WEI, Z C J XU. The comprehensive understanding of as an evaluation parameter for electrochemical water splitting. Small Methods, 2, 1800168(2018).

[17] M SEREDYCH, D HULICOVA-JURCAKOVA, Q LU G et al. Surface functional groups of carbons and the effects of their chemical character, density and accessibility to ions on electrochemical performance. Carbon, 46, 1475-1488(2008).

[18] H WU, W ZHOU, T YILDIRIM. Hydrogen storage in a prototypical zeolitic imidazolate framework-8. Journal of the American Chemical Society, 129, 5314-5315(2007).

[19] M YAGHI O, M LI G, L LI H. Selective binding and removal of guests in a microporous metal-organic framework. Nature, 378, 703-706(1995).

[20] M LI J, M KANG Y, D LIU et al. Nitrogen-doped graphitic carbon-supported ultrafine Co nanoparticles as an efficient multifunctional electrocatalyst for HER and rechargeable Zn-air batteries. ACS Applied Materials & Interfaces, 12, 5717-5729(2020).

[21] Y LI Z, X LIANG, M GAO Q et al. Fe, N co-doped carbonaceous hollow spheres with self-grown carbon nanotubes as a high performance binary electrocatalyst. Carbon, 154, 466-477(2019).

[22] H WU J, J HU L, N WANG et al. Surface confinement assisted synthesis of nitrogen-rich hollow carbon cages with Co nanoparticles as breathable electrodes for Zn-air batteries. Applied Catalysis B: Environmental, 254, 55-65(2019).

[23] J LI H, Y HE, T HE et al. ZIF-derived Co nanoparticle/N-doped CNTs composites embedded in N-doped carbon substrate as efficient electrocatalyst for hydrogen and oxygen evolution. Journal of Materials Science: Materials in Electronics, 30, 21388-21397(2019).

[24] N HAN M, J SHI M, J WANG et al. Efficient bifunctional Co/N dual-doped carbon electrocatalysts for oxygen reduction and evolution reaction. Carbon, 153, 575-584(2019).

[25] Y YUAN Q, X YU Y, J GONG Y et al. Three-dimensional N-doped carbon nanotube frameworks on Ni foam derived from a metal-organic framework as a bifunctional electrocatalyst for overall water splitting. ACS Applied Materials & Interfaces, 12, 3592-3602(2019).

[26] N GUAN Y, H LIU G, D LI J et al. Surface-engineered cobalt nitride composite as efficient bifunctional oxygen electrocatalyst. Nanotechnology, 30, 495406(2019).

[27] Q JIA Q, Y GAO, Y LI et al. Cobalt nanoparticles embedded in N-doped carbon on carbon cloth as free-standing electrodes for electrochemically-assisted catalytic oxidation of phenol and overall water splitting. Carbon, 155, 287-297(2019).

[28] C DU, J GAO Y, G WANG J et al. A new strategy for engineering a hierarchical porous carbon-anchored Fe single-atom electrocatalyst and the insights into its bifunctional catalysis for flexible rechargeable Zn-air batteries. Journal of Materials Chemistry A, 8, 9981-9990(2020).

[29] F LI, F HAN G, J NOH H et al. Boosting oxygen reduction catalysis with abundant copper single atom active sites. Energy & Environmental Science, 11, 2263-2269(2018).

[30] H HAN Y, G WANG Y, X CHEN W et al. Hollow N-doped carbon spheres with isolated cobalt single atomic sites: superior electrocatalysts for oxygen reduction. Journal of the American Chemical Society, 139, 17269-17272(2017).

[31] M BING Q, W LIU, C YI W et al. Ni anchored C₂N monolayers as low-cost and efficient catalysts for hydrogen production from formic acid. Journal of Power Sources, 413, 399-407(2019).

[32] B WU J, H ZHOU, Q LI et al. Densely populated isolated single Co-N site for efficient oxygen electrocatalysis. Advanced Energy Materials, 9, 1900149(2019).

[33] C WAN W, A TRIANA C, G LAN J et al. Bifunctional single atom electrocatalysts: coordination-performance correlations and reaction pathways. ACS Nano, 14, 13279-13293(2020).

[34] Q ZHANG Q, Y DUAN Z, M LI et al. Atomic cobalt catalysts for the oxygen evolution reaction. Chemical Communications, 56, 794-797(2020).

[35] B ZHANG H, Y LIU Y, T CHEN et al. Unveiling the activity origin of electrocatalytic oxygen evolution over isolated Ni atoms supported on a N-doped carbon matrix. Advanced Materials, 31, 1904548(2019).

[36] Y FU, Y YU H, C JIANG et al. NiCo alloy nanoparticles decorated on N-doped carbon nanofibers as highly active and durable oxygen electrocatalyst. Advanced Functional Materials, 28, 1705094(2018).

[37] L CHEN, X XU Z, J HAN W et al. Bimetallic CoNi alloy nanoparticles embedded in pomegranate-like nitrogen-doped carbon spheres for electrocatalytic oxygen reduction and evolution. ACS Applied Nano Materials, 3, 1354-1362(2020).

[38] P LIU G, B WANG, H DING P et al. In-situ synthesis strategy for CoM (M= Fe, Ni, Cu) bimetallic nanoparticles decorated N-doped 1D carbon nanotubes/3D porous carbon for electrocatalytic oxygen evolution reaction. Journal of Alloys and Compounds, 815, 152470(2020).

[39] L LI G, C XU X, B YANG B et al. Micelle-template synthesis of a 3D porous FeNi alloy and nitrogen-codoped carbon material as a bifunctional oxygen electrocatalyst. Electrochimica Acta, 331, 135375(2020).

[40] Z LI X, Y FANG Y, Q LIN X et al. MOF derived Co₃O₄ nanoparticles embedded in N-doped mesoporous carbon layer/ MWCNT hybrids: extraordinary bi-functional electrocatalysts for OER and ORR. Journal of Materials Chemistry A, 3, 17392-17402(2015).

[41] Y YUE X, S SONG C, Y YAN Z et al. Reduced graphene oxide supported nitrogen-doped porous carbon-coated NiFe alloy composite with excellent electrocatalytic activity for oxygen evolution reaction. Applied Surface Science, 493, 963-974(2019).

[42] L LI C, C WU M, R LIU. High-performance bifunctional oxygen electrocatalysts for zinc-air batteries over mesoporous Fe/Co-NC nanofibers with embedding FeCo alloy nanoparticles. Applied Catalysis B: Environmental, 244, 150-158(2019).

[43] Z WANG, M ANG J, W ZHANG B et al. FeCo/FeCoNi/N-doped carbon nanotubes grafted polyhedron-derived hybrid fibers as bifunctional oxygen electrocatalysts for durable rechargeable zinc-air battery. Applied Catalysis B: Environmental, 254, 26-36(2019).

[44] F LI T, L LI S, Y LIU Q et al. Immobilization of Ni₃Co nanoparticles into N-doped carbon nanotube/nanofiber integrated hierarchically branched architectures toward efficient overall water splitting. Advanced Science, 7, 1902371(2020).

[45] D CHEN, W ZHU J, Q MU X et al. Nitrogen-doped carbon coupled FeNi₃ intermetallic compound as advanced bifunctional electrocatalyst for OER, ORR and Zn-air batteries. Applied Catalysis B: Environmental, 268, 118729(2020).

[46] J ZHANG X, F CHEN Y, B WANG et al. FeNi nanoparticles embedded porous nitrogen-doped nanocarbon as efficient electrocatalyst for oxygen evolution reaction. Electrochimica Acta, 321, 134720(2019).

[47] Y WANG Z, B LIAO X, F LIN Z et al. 3D Nitrogen-doped graphene encapsulated metallic nickel-iron alloy nanoparticles for efficient bifunctional oxygen electrocatalysis. Chemistry-A European Journal, 26, 4044-4051(2020).

[48] H LEI, L WANG Z, F YANG et al. NiFe nanoparticles embedded N-doped carbon nanotubes as high-efficient electrocatalysts for wearable solid-state Zn-air batteries. Nano Energy, 68, 104293(2020).

[49] Y JIN Q, W REN B, P CHEN J et al. A facile method to conduct 3D self-supporting Co-FeCo/N-doped graphene-like carbon bifunctional electrocatalysts for flexible solid-state zinc air battery. Applied Catalysis B: Environmental, 256, 117887(2019).

[50] F XU Q, H JIANG, H LI Y et al. In-situ enriching active sites on co-doped Fe-Co₄N@NC nanosheet array as air cathode for flexible rechargeable Zn-air batteries. Applied Catalysis B: Environmental, 256, 117893(2019).

[51] X XIAO, H LI X, Q YU G et al. FeCo_x alloy nanoparticles encapsulated in three-dimensionally N-doped porous carbon/multiwalled carbon nanotubes composites as bifunctional electrocatalyst for zinc-air battery. Journal of Power Sources, 438, 227019(2019).

[52] S GUPTA, A YADAV, S BHARTIYA et al. Co oxide nanostructures for electrocatalytic water-oxidation: effects of dimensionality and related properties. Nanoscale, 10, 8806-8819(2018).

[53] G OU, X FAN P, J ZHANG H et al. Large-scale hierarchical oxide nanostructures for high-performance electrocatalytic water splitting. Nano Energy, 35, 207-214(2017).

[54] Z KONG D, Y WANG, Z HUANG S et al. 3D self-branched zinc-cobalt oxide@N-doped carbon hollow nanowall arrays for high-performance asymmetric supercapacitors and oxygen electrocatalysis. Energy Storage Materials, 23, 653-663(2019).

[55] J XIE A, J ZHANG, X TAO et al. Nickel-based MOF derived Ni@NiO/N-C nanowires with core-shell structure for oxygen evolution reaction. Electrochimica Acta, 324, 134814(2019).

[56] L XU, Q ZOU Y, H XIAO Z et al. Transforming Co₃O₄ nanosheets into porous N-doped Co_xO_y nanosheets with oxygen vacancies for the oxygen evolution reaction. Journal of Energy Chemistry, 35, 24-29(2019).

[57] X HE, Z LUAN S, L WANG et al. Facile loading mesoporous Co₃O₄ on nitrogen doped carbon matrix as an enhanced oxygen electrode catalyst. Materials Letters, 244, 78-82(2019).

[58] Y JIN H, J WANG, F SU D et al. In situ cobalt-cobalt oxide/ N-doped carbon hybrids as superior bifunctional electrocatalysts for hydrogen and oxygen evolution. Journal of the American Chemical Society, 137, 2688-2694(2015).

[59] R LI X, L WEI J, Q LI et al. Nitrogen-doped cobalt oxide nanostructures derived from cobalt-alanine complexes for high- performance oxygen evolution reactions. Advanced Functional Materials, 28, 1800886(2018).

[60] L ZHANG K, H XIA X, J DENG S et al. N-doped CoO nanowire arrays as efficient electrocatalysts for oxygen evolution reaction. Journal of Energy Chemistry, 37, 13-17(2019).

[61] J DING Y, Y YANG W, S GAO et al. Strongly cooperative nano-CoO/Co active phase in hierarchically porous nitrogen-doped carbon microspheres for efficient bifunctional oxygen electrocatalysis. ACS Applied Energy Materials, 3, 1328-1337(2019).