Discover the SciOpen Platform and Achieve Your Research Goals with Ease.
Search articles, authors, keywords, DOl and etc.
The electrochemical oxygen reduction reaction (ORR) is pivotal in energy conversion via a 4e− ORR pathway and green hydrogen peroxide production via 2e− ORR pathway. Transition metal single atom catalysts (TM SACs) have attracted intense attention in recent years for ORR due to their high activity and near maximum metal atom utilization. The future development of TM SACs for ORR requires improved understanding of reaction pathways, since currently the true origin of activity remains contentious owing to the lack of qualitative/quantitative information about active sites. Knowledge-guided design is imperative for the optimization of TM SACs performance in terms of activity and selectivity. This review focuses on the latest progress in the design of TM SACs for ORR, placing particular attention on efforts to elucidate reaction mechanisms. Experimental evidence based on in-situ/operando characterization measurements, along with theoretical predictions, are summarized to deepen understanding of the structure-performance relationships at both atomic and molecular level. Finally, some perspectives are offered relating to the fundamental science needed for TM SACs to find practical application in energy storage and conversion devices. We hope this review will inspire the development of new synthetic routes towards high-performance ORR electrocatalysts for the energy sector.
Tian, X. L.; Zhao, X.; Su, Y. Q.; Wang, L. J.; Wang, H. M.; Dang, D.; Chi, B.; Liu, H. F.; Hensen, E. J. M.; Lou, X. W. et al. Engineering bunched Pt-Ni alloy nanocages for efficient oxygen reduction in practical fuel cells. Science 2019, 366, 850–856.
Jung, E. H.; Jeon, N. J.; Park, E. Y.; Moon, C. S.; Shin, T. J.; Yang, T. Y.; Noh, J. H.; Seo, J. Efficient, stable and scalable perovskite solar cells using poly(3-hexylthiophene). Nature 2019, 567, 511–515.
Chu, S.; Cui, Y.; Liu, N. The path towards sustainable energy. Nat. Mater. 2017, 16, 16–22.
Wang, X. X.; Prabhakaran, V.; He, Y. H.; Shao, Y. Y.; Wu, G. Iron-free cathode catalysts for proton-exchange-membrane fuel cells: Cobalt catalysts and the peroxide mitigation approach. Adv. Mater. 2019, 31, 1805126.
Fu, H. T.; Wang, Z. H.; Sun, Y. M. Polymer donors for high-performance non-fullerene organic solar cells. Angew. Chem., Int. Ed. 2019, 58, 4442–4453.
Chang, J. W.; Yu, C.; Song, X. D.; Tan, X. Y.; Ding, Y. W.; Zhao, Z. B.; Qiu, J. S. A C-S-C linkage-triggered ultrahigh nitrogen-doped carbon and the identification of active site in triiodide reduction. Angew. Chem. , Int. Ed. 2021, 60, 3587–3595.
Ding, P.; Song, H. Q.; Chang, J. W.; Lu, S. N-doped carbon dots coupled NiFe-LDH hybrids for robust electrocatalytic alkaline water and seawater oxidation. Nano Res. 2022, 15, 7063–7070.
Gu, J. W.; Peng, Y.; Zhou, T.; Ma, J.; Pang, H.; Yamauchi, Y. Porphyrin-based framework materials for energy conversion. Nano Res. Energy 2022, 1, e9120009.
Xue, H. R.; Gong, H.; Yamauchi, Y.; Sasaki, T.; Ma, R. Z. Photo-enhanced rechargeable high-energy-density metal batteries for solar energy conversion and storage. Nano Res. Energy 2022, 1, e9120007.
Xu, Y. Y.; Xue, H. R.; Li, X. J.; Fan, X. L.; Li, P.; Zhang, T. F.; Chang, K.; Wang, T.; He, J. P. Application of metal-organic frameworks, covalent organic frameworks and their derivates for the metal-air batteries. Nano Res. Energy 2023, 2, e9120052.
Ge, H. Y.; Feng, X. L.; Liu, D. P.; Zhang, Y. Recent advances and perspectives for Zn-based batteries: Zn anode and electrolyte. Nano Res. Energy 2023, 2, e9120039.
Asset, T.; Atanassov, P. Iron-nitrogen-carbon catalysts for proton exchange membrane fuel cells. Joule 2020, 4, 33–44.
Li, M.; Bi, X. X.; Wang, R. Y.; Li, Y. B.; Jiang, G. P.; Li, L.; Zhong, C.; Chen, Z. W.; Lu, J. Relating catalysis between fuel cell and metal-air batteries. Matter 2020, 2, 32–49.
Wang, H. F.; Xu, Q. Materials design for rechargeable metal-air batteries. Matter 2019, 1, 565–595.
Wang, K.; Lu, Z. J.; Lei, J.; Liu, Z. Y.; Li, Y. Z.; Cao, Y. L. Modulation of ligand fields in a single-atom site by the molten salt strategy for enhanced oxygen bifunctional activity for zinc-air batteries. ACS Nano 2022, 16, 11944–11956.
Gasteiger, H. A.; Marković, N. M. Just a dream-or future reality? Science 2009, 324, 48–49.
Siahrostami, S.; Verdaguer-Casadevall, A.; Karamad, M.; Deiana, D.; Malacrida, P.; Wickman, B.; Escudero-Escribano, M.; Paoli, E. A.; Frydendal, R.; Hansen, T. W. et al. Enabling direct H2O2 production through rational electrocatalyst design. Nat. Mater. 2013, 12, 1137–1143.
Verdaguer-Casadevall, A.; Deiana, D.; Karamad, M.; Siahrostami, S.; Malacrida, P.; Hansen, T. W.; Rossmeisl, J.; Chorkendorff, I.; Stephens, I. E. L. Trends in the electrochemical synthesis of H2O2: Enhancing activity and selectivity by electrocatalytic site engineering. Nano Lett. 2014, 14, 1603–1608.
Jirkovský, J. S.; Panas, I.; Ahlberg, E.; Halasa, M.; Romani, S.; Schiffrin, D. J. Single atom hot-spots at Au-Pd nanoalloys for electrocatalytic H2O2 production. J. Am. Chem. Soc. 2011, 133, 19432–19441.
Zhao, J. J.; Fu, C. H.; Ye, K.; Liang, Z.; Jiang, F. L.; Shen, S. Y.; Zhao, X. R.; Ma, L.; Shadike, Z.; Wang, X. M. et al. Manipulating the oxygen reduction reaction pathway on Pt-coordinated motifs. Nat. Commun. 2022, 13, 685.
Yang, Y.; Agarwal, R. G.; Hutchison, P.; Rizo, R.; Soudackov, A. V.; Lu, X. Y.; Herrero, E.; Feliu, J. M.; Hammes-Schiffer, S.; Mayer, J. M. et al. Inverse kinetic isotope effects in the oxygen reduction reaction at platinum single crystals. Nat. Chem. 2023, 15, 271.
Yan, Q. Q.; Wu, D. X.; Chu, S. Q.; Chen, Z. Q.; Lin, Y.; Chen, M. X.; Zhang, J.; Wu, X. J.; Liang, H. W. Reversing the charge transfer between platinum and sulfur-doped carbon support for electrocatalytic hydrogen evolution. Nat. Commun. 2019, 10, 4977.
Tang, C.; Jiao, Y.; Shi, B. Y.; Liu, J. N.; Xie, Z. H.; Chen, X.; Zhang, Q.; Qiao, S. Z. Coordination tunes selectivity: Two-electron oxygen reduction on high-loading molybdenum single-atom catalysts. Angew. Chem. , Int. Ed. 2020, 59, 9171–9176.
Sa, Y. J.; Seo, D. J.; Woo, J.; Lim, J. T.; Cheon, J. Y.; Yang, S. Y.; Lee, J. M.; Kang, D.; Shin, T. J.; Shin, H. S. et al. A general approach to preferential formation of active Fe-Nx sites in Fe-N/C electrocatalysts for efficient oxygen reduction reaction. J. Am. Chem. Soc. 2016, 138, 15046–15056.
Wang, J.; Huang, Z. Q.; Liu, W.; Chang, C. R.; Tang, H. L.; Li, Z. J.; Chen, W. X.; Jia, C. J.; Yao, T.; Wei, S. Q. et al. Design of N-coordinated dual-metal sites: A stable and active Pt-free catalyst for acidic oxygen reduction reaction. J. Am. Chem. Soc. 2017, 139, 17281–17284.
Xiao, C. Q.; Cheng, L.; Zhu, Y. H.; Wang, G. C.; Chen, L. Y.; Wang, Y. T.; Chen, R. Z.; Li, Y. H.; Li, C. Z. Super-coordinated nickel N4Ni1O2 site single-atom catalyst for selective H2O2 electrosynthesis at high current densities. Angew. Chem., Int. Ed. 2022, 61, e202206544.
Yang, G. G.; Zhu, J. W.; Yuan, P. F.; Hu, Y. F.; Qu, G.; Lu, B. A.; Xue, X. Y.; Yin, H. B.; Cheng, W. Z.; Cheng, J. Q. et al. Regulating Fe-spin state by atomically dispersed Mn-N in Fe-N-C catalysts with high oxygen reduction activity. Nat. Commun. 2021, 12, 1734.
Yin, P. Q.; Yao, T.; Wu, Y. E.; Zheng, L. R.; Lin, Y.; Liu, W.; Ju, H. X.; Zhu, J. F.; Hong, X.; Deng, Z. X. et al. Single cobalt atoms with precise N-coordination as superior oxygen reduction reaction catalysts. Angew. Chem. , Int. Ed. 2016, 55, 10800–10805.
Chang, J. W.; Song, X. D.; Yu, C.; Yu, J. H.; Ding, Y. W.; Yao, C.; Zhao, Z. B.; Qiu, J. S. Hydrogen-bonding triggered assembly to configure hollow carbon nanosheets for highly efficient tri-iodide reduction. Adv. Funct. Mater. 2020, 30, 2006270.
Chang, J. W.; Yu, C.; Song, X. D.; Han, X. T.; Ding, Y. W.; Tan, X. Y.; Li, S. F.; Xie, Y. Y.; Zhao, Z. B.; Qiu, J. S. Mechanochemistry-driven prelinking enables ultrahigh nitrogen-doping in carbon materials for triiodide reduction. Nano Energy 2021, 89, 106332.
Sheng, H. Y.; Hermes, E. D.; Yang, X. H.; Ying, D. W.; Janes, A. N.; Li, W. J.; Schmidt, J. R.; Jin, S. Electrocatalytic production of H2O2 by selective oxygen reduction using earth-abundant cobalt pyrite (CoS2). ACS Catal. 2019, 9, 8433–8442.
Zhao, W. W.; Bothra, P.; Lu, Z. Y.; Li, Y. B.; Mei, L. P.; Liu, K.; Zhao, Z. H.; Chen, G. X.; Back, S.; Siahrostami, S. et al. Improved oxygen reduction reaction activity of nanostructured CoS2 through electrochemical tuning. ACS Appl. Energy Mater. 2019, 2, 8605–8614.
An, C. H.; Kang, W.; Deng, Q. B.; Hu, N. Pt and Te codoped ultrathin MoS2 nanosheets for enhanced hydrogen evolution reaction with wide pH range. Rare Met. 2022, 41, 378–384.
Abbott, D. F.; Mukerjee, S.; Petrykin, V.; Bastl, Z.; Halck, N. B.; Rossmeisl, J.; Krtil, P. Oxygen reduction on nanocrystalline ruthenia-local structure effects. RSC Adv. 2015, 5, 1235–1243.
Huang, J. H.; Chen, J. X.; Fu, C. L.; Cai, P. W.; Li, Y.; Cao, L. L.; Liu, W.; Yu, P.; Wei, S. Q.; Wen, Z. H. et al. 2D hybrid of Ni-LDH chips on carbon nanosheets as cathode of zinc-air battery for electrocatalytic conversion of O2 into H2O2. ChemSusChem 2020, 13, 1496–1503.
Fan, H.; Mao, K.; Liu, M.; Zhuo, O.; Zhao, J.; Sun, T.; Jiang, Y. F.; Du, X.; Zhang, X. L.; Wu, Q. S. et al. Tailoring the nano heterointerface of hematite/magnetite on hierarchical nitrogen-doped carbon nanocages for superb oxygen reduction. J. Mater. Chem. A 2018, 6, 21313–21319.
Cao, M. M.; Liu, Y. Y.; Sun, K.; Li, H.; Lin, X. Q.; Zhang, P. X.; Zhou, L. M.; Wang, A.; Mehdi, S.; Wu, X. L. et al. Coupling Fe3C nanoparticles and N-doping on wood-derived carbon to construct reversible cathode for Zn-air batteries. Small 2022, 18, 2202014.
Lian, Y. B.; Shi, K. F.; Yang, H. J.; Sun, H.; Qi, P. W.; Ye, J.; Wu, W. B.; Deng, Z.; Peng, Y. Elucidation of active sites on S, N codoped carbon cubes embedding Co-Fe carbides toward reversible oxygen conversion in high-performance zinc-air batteries. Small 2020, 16, 1907368.
Sahoo, S. K.; Ye, Y.; Lee, S.; Park, J.; Lee, H.; Lee, J.; Han, J. W. Rational design of TiC-supported single-atom electrocatalysts for hydrogen evolution and selective oxygen reduction reactions. ACS Energy Lett. 2019, 4, 126–132.
Zeng, R.; Yang, Y.; Feng, X. R.; Li, H. Q.; Gibbs, L. M.; DiSalvo, F. J.; Abruña, H. D. Nonprecious transition metal nitrides as efficient oxygen reduction electrocatalysts for alkaline fuel cells. Sci. Adv. 2022, 8, eabj1584.
Yang, Y.; Zeng, R.; Xiong, Y.; DiSalvo, F. J.; Abruña, H. D. Cobalt-based nitride-core oxide-shell oxygen reduction electrocatalysts. J. Am. Chem. Soc. 2019, 141, 19241–19245.
Guo, F. J.; Zhang, M. Y.; Yi, S. C.; Li, X. X.; Xin, R.; Yang, M.; Liu, B.; Chen, H. B.; Li, H. M.; Liu, Y. J. Metal-coordinated porous polydopamine nanospheres derived Fe3N-FeCo encapsulated N-doped carbon as a highly efficient electrocatalyst for oxygen reduction reaction. Nano Res. Energy 2022, 1, e9120027.
Yan, X. Y.; Wang, B. B.; Ren, J.; Long, X. J.; Yang, D. J. An unsaturated bond strategy to regulate active centers of metal-free covalent organic frameworks for efficient oxygen reduction. Angew. Chem., Int. Ed. 2022, 61, e202209583.
Wu, Q. L.; Jia, Y.; Liu, Q.; Mao, X.; Guo, Q.; Yan, X. C.; Zhao, J. P.; Liu, F. C.; Du, A. J.; Yao, X. D. Ultra-dense carbon defects as highly active sites for oxygen reduction catalysis. Chem 2022, 8, 2715–2733.
Zhang, L. J.; Gu, T. T.; Lu, K. L.; Zhou, L. J.; Li, D. S.; Wang, R. H. Engineering synergistic edge-N dipole in metal-free carbon nanoflakes toward intensified oxygen reduction electrocatalysis. Adv. Funct. Mater. 2021, 31, 2103187.
Han, G. F.; Li, F.; Zou, W.; Karamad, M.; Jeon, J. P.; Kim, S. W.; Kim, S. J.; Bu, Y. F.; Fu, Z. P.; Lu, Y. L. et al. Building and identifying highly active oxygenated groups in carbon materials for oxygen reduction to H2O2. Nat. Commun. 2020, 11, 2209.
Yan, J. X.; Ye, F. H.; Dai, Q. B.; Ma, X. Y.; Fang, Z. H.; Dai, L. M.; Hu, C. G. Recent progress in carbon-based electrochemical catalysts: From structure design to potential applications. Nano Res. Energy 2023, 2, e9120047.
Fu, R.; Song, H. Q.; Liu, X. J.; Zhang, Y. Q.; Xiao, G. J.; Zou, B.; Waterhouse, G. I. N.; Lu, S. Y. Disulfide crosslinking-induced aggregation: Towards solid-state fluorescent carbon dots with vastly different emission colors. Chin. J. Chem. 2023, 41, 1007–1014.
Wang, B. Y.; Wei, Z. H.; Sui, L.; Yu, J. K.; Zhang, B. W.; Wang, X. Y.; Feng, S. N.; Song, H. Q.; Yong, X.; Tian, Y. X. et al. Electron-phonon coupling-assisted universal red luminescence of o-phenylenediamine-based carbon dots. Light Sci. Appl. 2022, 11, 172.
Zhang, L. Z.; Fischer, J. M. T. A.; Jia, Y.; Yan, X. C.; Xu, W.; Wang, X. Y.; Chen, J.; Yang, D. J.; Liu, H. W.; Zhuang, L. Z. et al. Coordination of atomic Co-Pt coupling species at carbon defects as active sites for oxygen reduction reaction. J. Am. Chem. Soc. 2018, 140, 10757–10763.
Yang, Z. K.; Wang, Y.; Zhu, M. Z.; Li, Z. J.; Chen, W. X.; Wei, W. C.; Yuan, T. W.; Qu, Y. T.; Xu, Q.; Zhao, C. M. et al. Boosting oxygen reduction catalysis with Fe-N4 sites decorated porous carbons toward fuel cells. ACS Catal. 2019, 9, 2158–2163.
Qiao, B. T.; Wang, A. Q.; Yang, X. F.; Allard, L. F.; Jiang, Z.; Cui, Y. T.; Liu, J. Y.; Li, J.; Zhang, T. Single-atom catalysis of CO oxidation using Pt1/FeOx. Nat. Chem. 2011, 3, 634–641.
Siahrostami, S.; Villegas, S. J.; Mostaghimi, A. H. B.; Back, S.; Farimani, A. B.; Wang, H. T.; Persson, K. A.; Montoya, J. A review on challenges and successes in atomic-scale design of catalysts for electrochemical synthesis of hydrogen peroxide. ACS Catal. 2020, 10, 7495–7511.
Wang, H.; Liu, R. P.; Li, Y. T.; Lü, X. J.; Wang, Q.; Zhao, S. Q.; Yuan, K. J.; Cui, Z. M.; Li, X.; Xin, S. et al. Durable and efficient hollow porous oxide spinel microspheres for oxygen reduction. Joule 2018, 2, 337–348.
Chen, S. Y.; Luo, T.; Li, X. Q.; Chen, K. J.; Fu, J. W.; Liu, K.; Cai, C.; Wang, Q. Y.; Li, H. M.; Chen, Y. et al. Identification of the highly active Co-N4 coordination motif for selective oxygen reduction to hydrogen peroxide. J. Am. Chem. Soc. 2022, 144, 14505–14516.
Tang, C.; Chen, L.; Li, H. J.; Li, L. Q.; Jiao, Y.; Zheng, Y.; Xu, H. L.; Davey, K.; Qiao, S. Z. Tailoring acidic oxygen reduction selectivity on single-atom catalysts via modification of first and second coordination spheres. J. Am. Chem. Soc. 2021, 143, 7819–7827.
Jung, E.; Shin, H.; Lee, B. H.; Efremov, V.; Lee, S.; Lee, H. S.; Kim, J.; Antink, W. H.; Park, S.; Lee, K. S. et al. Atomic-level tuning of Co-N-C catalyst for high-performance electrochemical H2O2 production. Nat. Mater. 2020, 19, 436–442.
Li, B. Q.; Zhao, C. X.; Liu, J. N.; Zhang, Q. Eletrosynthesis of hydrogen peroxide synergistically catalyzed by atomic Co-Nx-C sites and oxygen functional groups in noble-metal-free electrocatalysts. Adv. Mater. c 2019, 31, 1808173.
Tian, Y. H.; Li, M.; Wu, Z. Z.; Sun, Q.; Yuan, D.; Johannessen, B.; Xu, L.; Wang, Y.; Dou, Y. H.; Zhao, H. J. et al. Edge-hosted atomic Co-N4 sites on hierarchical porous carbon for highly selective two-electron oxygen reduction reaction. Angew. Chem., Int. Ed. 2022, 134, e202213296.
Xia, C.; Xia, Y.; Zhu, P.; Fan, L.; Wang, H. T. Direct electrosynthesis of pure aqueous H2O2 solutions up to 20% by weight using a solid electrolyte. Science 2019, 366, 226–231.
Sun, Y. Y.; Han, L.; Strasser, P. A comparative perspective of electrochemical and photochemical approaches for catalytic H2O2 production. Chem. Soc. Rev. 2020, 49, 6605–6631.
Shan, J. Q.; Ye, C.; Zhu, C. Z.; Dong, J. C.; Xu, W. J.; Chen, L.; Jiao, Y.; Jiang, Y. L.; Song, L.; Zhang, Y. N. et al. Integrating interactive noble metal single-atom catalysts into transition metal oxide lattices. J. Am. Chem. Soc. 2022, 144, 23214–23222.
Campos-Martin, J. M.; Blanco-Brieva, G.; Fierro, J. L. G. Hydrogen peroxide synthesis: An outlook beyond the anthraquinone process. Angew. Chem., Int. Ed. 2006, 45, 6962–6984.
Edwards, J. K.; Hutchings, G. J. Palladium and gold-palladium catalysts for the direct synthesis of hydrogen peroxide. Angew. Chem. , Int. Ed. 2008, 47, 9192–9198.
Edwards, J. K.; Ntainjua, N. E.; Carley, A. F.; Herzing, A. A.; Kiely, C. J.; Hutchings, G. J. Direct synthesis of H2O2 from H2 and O2 over gold, palladium, and gold-palladium catalysts supported on acid-pretreated TiO2. Angew. Chem. , Int. Ed. 2009, 48, 8512–8515.
Chen, Z. H.; Chen, S. C.; Siahrostami, S.; Chakthranont, P.; Hahn, C.; Nordlund, D.; Dimosthenis, S.; Nørskov, J. K.; Bao, Z. N.; Jaramillo, T. F. Development of a reactor with carbon catalysts for modular-scale, low-cost electrochemical generation of H2O2. React. Chem. Eng. 2017, 2, 239–245.
Martínez-Huitle, C. A.; Ferro, S. Electrochemical oxidation of organic pollutants for the wastewater treatment: Direct and indirect processes. Chem. Soc. Rev. 2006, 35, 1324–1340.
Zhao, X.; Yin, Q.; Mao, X. N.; Cheng, C.; Zhang, L.; Wang, L.; Liu, T. F.; Li, Y. Y.; Li, Y. G. Theory-guided design of hydrogen-bonded cobaltoporphyrin frameworks for highly selective electrochemical H2O2 production in acid. Nat. Commun. 2022, 13, 2721.
Koper, M. T. M. Thermodynamic theory of multi-electron transfer reactions: Implications for electrocatalysis. J. Electroanal. Chem. 2011, 660, 254–260.
Kulkarni, A.; Siahrostami, S.; Patel, A.; Nørskov, J. K. Understanding catalytic activity trends in the oxygen reduction reaction. Chem. Rev. 2018, 118, 2302–2312.
Handoko, A. D.; Wei, F. X.; Jenndy, N.; Yeo, B. S.; Seh, Z. W. Understanding heterogeneous electrocatalytic carbon dioxide reduction through operando techniques. Nat. Catal. 2018, 1, 922–934.
Zhu, Y. P.; Wang, J. L.; Chu, H.; Chu, Y. C.; Chen, H. M. In situ/operando studies for designing next-generation electrocatalysts. ACS Energy Lett. 2020, 5, 1281–1291.
Li, X. N.; Wang, H. Y.; Yang, H. B.; Cai, W. Z.; Liu, S.; Liu, B. In situ/operando characterization techniques to probe the electrochemical reactions for energy conversion. Small Methods 2018, 2, 1700395.
Li, X. N.; Yang, X. F.; Zhang, J. M.; Huang, Y. Q.; Liu, B. In situ/operando techniques for characterization of single-atom catalysts. ACS Catal. 2019, 9, 2521–2531.
Van Oversteeg, C. H. M.; Doan, H. Q.; De Groot, F. M. F.; Cuk, T. In situ X-ray absorption spectroscopy of transition metal based water oxidation catalysts. Chem. Soc. Rev. 2017, 46, 102–125.
Li, J. K.; Gong, J. L. Operando characterization techniques for electrocatalysis. Energy Environ. Sci. 2020, 13, 3748–3779.
Gao, J. J.; Liu, B. Progress of electrochemical hydrogen peroxide synthesis over single atom catalysts. ACS Mater. Lett. 2020, 2, 1008–1024.
Wang, Y. L.; Waterhouse, G. I. N.; Shang, L.; Zhang, T. R. Electrocatalytic oxygen reduction to hydrogen peroxide: From homogeneous to heterogeneous electrocatalysis. Adv. Energy Mater. 2021, 11, 2003323.
Jiang, K.; Zhao, J. J.; Wang, H. T. Catalyst design for electrochemical oxygen reduction toward hydrogen peroxide. Adv. Funct. Mater. 2020, 30, 2003321.
Bu, Y. F.; Wang, Y. B.; Han, G. F.; Zhao, Y. X.; Ge, X. L.; Li, F.; Zhang, Z. H.; Zhong, Q.; Baek, J. B. Carbon-based electrocatalysts for efficient hydrogen peroxide production. Adv. Mater. 2021, 33, 2103266.
Shao, M. H.; Chang, Q. W.; Dodelet, J. P.; Chenitz, R. Recent advances in electrocatalysts for oxygen reduction reaction. Chem. Rev. 2016, 116, 3594–3657.
Yin, H. B.; Xia, H. C.; Zhao, S. Y.; Li, K. X.; Zhang, J. N.; Mu, S. C. Atomic level dispersed metal-nitrogen-carbon catalyst toward oxygen reduction reaction: Synthesis strategies and chemical environmental regulation. Energy Environ. Mater. 2021, 4, 5–18.
Wan, C. Z.; Duan, X. F.; Huang, Y. Molecular design of single-atom catalysts for oxygen reduction reaction. Adv. Energy Mater. 2020, 10, 1903815.
Deng, Y. J.; Luo, J. M.; Chi, B.; Tang, H. B.; Li, J.; Qiao, X. C.; Shen, Y. J.; Yang, Y. J.; Jia, C. M.; Rao, P. et al. Advanced atomically dispersed metal-nitrogen-carbon catalysts toward cathodic oxygen reduction in PEM fuel cells. Adv. Energy Mater. 2021, 11, 2101222.
Zhao, C. X.; Liu, J. N.; Wang, J.; Ren, D.; Li, B. Q.; Zhang, Q. Recent advances of noble-metal-free bifunctional oxygen reduction and evolution electrocatalysts. Chem. Soc. Rev. 2021, 50, 7745–7778.
Guo, D. H.; Shibuya, R.; Akiba, C.; Saji, S.; Kondo, T.; Nakamura, J. Active sites of nitrogen-doped carbon materials for oxygen reduction reaction clarified using model catalysts. Science 2016, 351, 361–365.
Choi, C. H.; Choi, W. S.; Kasian, O.; Mechler, A. K.; Sougrati, M. T.; Brüller, S.; Strickland, K.; Jia, Q. Y.; Mukerjee, S.; Mayrhofer, K. J. J. et al. Unraveling the nature of sites active toward hydrogen peroxide reduction in Fe-N-C catalysts. Angew. Chem. , Int. Ed. 2017, 56, 8809–8812.
Sun, Y. Y.; Silvioli, L.; Sahraie, N. R.; Ju, W.; Li, J. K.; Zitolo, A.; Li, S.; Bagger, A.; Arnarson, L.; Wang, X. L. et al. Activity-selectivity trends in the electrochemical production of hydrogen peroxide over single-site metal-nitrogen-carbon catalysts. J. Am. Chem. Soc. 2019, 141, 12372–12381.
Gao, J. J.; Yang, H. B.; Huang, X.; Hung, S. F.; Cai, W. Z.; Jia, C. M.; Miao, S.; Chen, H. M.; Yang, X. F.; Huang, Y. Q. et al. Enabling direct H2O2 production in acidic media through rational design of transition metal single atom catalyst. Chem 2020, 6, 658–674.
Liu, C.; Li, H.; Liu, F.; Chen, J. S.; Yu, Z. X.; Yuan, Z. W.; Wang, C. J.; Zheng, H. L.; Henkelman, G.; Wei, L. et al. Intrinsic activity of metal centers in metal-nitrogen-carbon single-atom catalysts for hydrogen peroxide synthesis. J. Am. Chem. Soc. 2020, 142, 21861–21871.
Zhou, W. L.; Su, H.; Cheng, W. R.; Li, Y. L.; Jiang, J. J.; Liu, M. H.; Yu, F. F.; Wang, W.; Wei, S. Q.; Liu, Q. H. Regulating the scaling relationship for high catalytic kinetics and selectivity of the oxygen reduction reaction. Nat. Commun. 2022, 13, 6414.
Zhang, W. Y.; Chao, Y. G.; Zhang, W. S.; Zhou, J. H.; Lv, F.; Wang, K.; Lin, F. X.; Luo, H.; Li, J.; Tong, M. P. et al. Emerging dual-atomic-site catalysts for efficient energy catalysis. Adv. Mater. 2021, 33, 2102576.
Shan, J. Q.; Ye, C.; Jiang, Y. L.; Jaroniec, M.; Zheng, Y.; Qiao, S. Z. Metal-metal interactions in correlated single-atom catalysts. Sci. Adv. 2022, 8, eabo0762.
Hu, L. Y.; Dai, C. L.; Chen, L. W.; Zhu, Y. H.; Hao, Y. C.; Zhang, Q. H.; Gu, L.; Feng, X.; Yuan, S.; Wang, L. et al. Metal-triazolate-framework-derived FeN4Cl1 single-atom catalysts with hierarchical porosity for the oxygen reduction reaction. Angew. Chem. , Int. Ed. 2021, 60, 27324–27329.
Shen, H. J.; Gracia-Espino, E.; Ma, J. Y.; Zang, K. T.; Luo, J.; Wang, L.; Gao, S. S.; Mamat, X.; Hu, G. Z.; Wagberg, T. et al. Synergistic effects between atomically dispersed Fe-N-C and C-S-C for the oxygen reduction reaction in acidic media. Angew. Chem., Int. Ed. 2017, 56, 13800–13804.
Shang, H. S.; Zhou, X. Y.; Dong, J. C.; Li, A.; Zhao, X.; Liu, Q. H.; Lin, Y.; Pei, J. J.; Li, Z.; Jiang, Z. L. et al. Engineering unsymmetrically coordinated Cu-S1N3 single atom sites with enhanced oxygen reduction activity. Nat. Commun. 2020, 11, 3049.
Yuan, K.; Lützenkirchen-Hecht, D.; Li, L. B.; Shuai, L.; Li, Y. Z.; Cao, R.; Qiu, M.; Zhuang, X. D.; Leung, M. K. H.; Chen, Y. W. et al. Boosting oxygen reduction of single iron active sites via geometric and electronic engineering: Nitrogen and phosphorus dual coordination. J. Am. Chem. Soc. 2020, 142, 2404–2412.
Chen, Y. J.; Gao, R.; Ji, S. F.; Li, H. J.; Tang, K.; Jiang, P.; Hu, H. B.; Zhang, Z. D.; Hao, H. G.; Qu, Q. Y. et al. Atomic-level modulation of electronic density at cobalt single-atom sites derived from metal-organic frameworks: Enhanced oxygen reduction performance. Angew. Chem. , Int. Ed. 2021, 60, 3212–3221.
Yang, L.; Shi, L.; Wang, D.; Lv, Y. L.; Cao, D. P. Single-atom cobalt electrocatalysts for foldable solid-state Zn-air battery. Nano Energy 2018, 50, 691–698.
Chen, K. J.; Liu, K.; An, P. D.; Li, H. J. W.; Lin, Y. Y.; Hu, J. H.; Jia, C. K.; Fu, J. W.; Li, H. M.; Liu, H. et al. Iron phthalocyanine with coordination induced electronic localization to boost oxygen reduction reaction. Nat. Commun. 2020, 11, 4173.
Yu, L.; Li, Y. C.; Ruan, Y. F. Dynamic control of sacrificial bond transformation in the Fe-N-C single-atom catalyst for molecular oxygen reduction. Angew. Chem. , Int. Ed. 2021, 60, 25296–25301.
Lin, L. X.; Miao, N. H.; Wallace, G. G.; Chen, J.; Allwood, D. A. Engineering carbon materials for electrochemical oxygen reduction reactions. Adv. Energy Mater. 2021, 11, 2100695.
He, F.; Zheng, Y.; Fan, H. L.; Ma, D. L.; Chen, Q. F.; Wei, T.; Wu, W. B.; Wu, D.; Hu, X. Oxidase-inspired selective 2e/4e reduction of oxygen on electron-deficient Cu. ACS Appl. Mater. Interfaces 2020, 12, 4833–4842.
Han, Y. H.; Wang, Y. G.; Xu, R. R.; Chen, W. X.; Zheng, L. R.; Han, A. J.; Zhu, Y. Q.; Zhang, J.; Zhang, H. B.; Luo, J. et al. Electronic structure engineering to boost oxygen reduction activity by controlling the coordination of the central metal. Energy Environ. Sci. 2018, 11, 2348–2352.
Jiang, K.; Back, S.; Akey, A. J.; Xia, C.; Hu, Y. F.; Liang, W. T.; Schaak, D.; Stavitski, E.; Nørskov, J. K.; Siahrostami, S. et al. Highly selective oxygen reduction to hydrogen peroxide on transition metal single atom coordination. Nat. Commun. 2019, 10, 3997.
Luo, X.; Wei, X. Q.; Wang, H. J.; Gu, W. L.; Kaneko, T.; Yoshida, Y.; Zhao, X.; Zhu, C. Z. Secondary-atom-doping enables robust Fe-N-C single-atom catalysts with enhanced oxygen reduction reaction. Nano-Micro Lett. 2020, 12, 163.
Hai, X.; Zhao, X. X.; Guo, N.; Yao, C. H.; Chen, C.; Liu, W.; Du, Y. H.; Yan, H.; Li, J.; Chen, Z. X. et al. Engineering local and global structures of single Co atoms for a superior oxygen reduction reaction. ACS Catal. 2020, 10, 5862–5870.
Xu, H. B.; Jia, H. X.; Li, H. Z.; Liu, J.; Gao, X. W.; Zhang, J. C.; Liu, M.; Sun, D. L.; Chou, S. L.; Fang, F. et al. Dual carbon-hosted Co-N3 enabling unusual reaction pathway for efficient oxygen reduction reaction. Appl. Catal. B Environ. 2021, 297, 120390.
Xue, D. P.; Yuan, P. F.; Jiang, S.; Wei, Y. F.; Zhou, Y.; Dong, C. L.; Yan, W. F.; Mu, S. C.; Zhang, J. N. Altering the spin state of Fe-N-C through ligand field modulation of single-atom sites boosts the oxygen reduction reaction. Nano Energy 2023, 105, 108020.
Sheng, Z. H.; Shao, L.; Chen, J. J.; Bao, W. J.; Wang, F. B.; Xia, X. H. Catalyst-free synthesis of nitrogen-doped graphene via thermal annealing graphite oxide with melamine and its excellent electrocatalysis. ACS Nano 2011, 5, 4350–4358.
Yang, L.; Cheng, D. J.; Xu, H. X.; Zeng, X. F.; Wan, X.; Shui, J. L.; Xiang, Z. H.; Cao, D. P. Unveiling the high-activity origin of single-atom iron catalysts for oxygen reduction reaction. Proc. Natl. Acad. Sci. USA 2018, 115, 6626–6631.
Zhang, N.; Zhou, T. P.; Chen, M. L.; Feng, H.; Yuan, R. L.; Zhong, C. A.; Yan, W. S.; Tian, Y. C.; Wu, X. J.; Chu, W. S. et al. High-purity pyrrole-type FeN4 sites as a superior oxygen reduction electrocatalyst. Energy Environ. Sci. 2020, 13, 111–118.
Hu, X.; Chen, S. Y.; Chen, L. T.; Tian, Y.; Yao, S.; Lu, Z. Y.; Zhang, X.; Zhou, Z. What is the real origin of the activity of Fe-N-C electrocatalysts in the O2 reduction reaction? Critical roles of coordinating Pyrrolic N and axially adsorbing species. J. Am. Chem. Soc. 2022, 144, 18144–18152.
Guo, J.; Yan, X. M.; Liu, Q.; Li, Q.; Xu, X.; Kang, L. T.; Cao, Z. M.; Chai, G. L.; Chen, J.; Wang, Y. B. et al. The synthesis and synergistic catalysis of iron phthalocyanine and its graphene-based axial complex for enhanced oxygen reduction. Nano Energy 2018, 46, 347–355.
Zhao, K. M.; Liu, S. Q.; Li, Y. Y.; Wei, X. L.; Ye, G. Y.; Zhu, W. W.; Su, Y. K.; Wang, J.; Liu, H. T.; He, Z. et al. Insight into the mechanism of axial ligands regulating the catalytic activity of Fe-N4 sites for oxygen reduction reaction. Adv. Energy Mater. 2022, 12, 2103588.
Gotico, P.; Boitrel, B.; Guillot, R.; Sircoglou, M.; Quaranta, A.; Halime, Z.; Leibl, W.; Aukauloo, A. Second-sphere biomimetic multipoint hydrogen-bonding patterns to boost CO2 reduction of iron porphyrins. Angew. Chem. , Int. Ed. 2019, 58, 4504–4509.
Min, Y.; Zhou, X.; Chen, J. J.; Chen, W. X.; Zhou, F. Y.; Wang, Z. Y.; Yang, J.; Xiong, C.; Wang, Y.; Li, F. T. et al. Integrating single-cobalt-site and electric field of boron nitride in dechlorination electrocatalysts by bioinspired design. Nat. Commun. 2021, 12, 303.
Jin, Z. Y.; Li, P. P.; Meng, Y.; Fang, Z. W.; Xiao, D.; Yu, G. H. Understanding the inter-site distance effect in single-atom catalysts for oxygen electroreduction. Nat. Catal. 2021, 4, 615–622.
Zhao, S. N.; Li, J. K.; Wang, R.; Cai, J. M.; Zang, S. Q. Electronically and geometrically modified single-atom Fe sites by adjacent Fe nanoparticles for enhanced oxygen reduction. Adv. Mater. 2022, 34, 2107291.
Cheng, X. Y.; Yang, J.; Yan, W.; Han, Y.; Qu, X. M.; Yin, S. H.; Chen, C.; Ji, R. Y.; Li, Y. R.; Li, G. et al. Nano-geometric deformation and synergistic Co nanoparticles-Co-N4 composite sites for proton exchange membrane fuel cells. Energy Environ. Sci. 2021, 14, 5958–5967.
Cheng, Y. J.; Song, H. Q.; Yu, J. K.; Chang, J. W.; Waterhouse, G. I. N.; Tang, Z. Y.; Yang, B.; Lu, S. Y. Carbon dots-derived carbon nanoflowers decorated with cobalt single atoms and nanoparticles as efficient electrocatalysts for oxygen reduction. Chinese J. Catal. 2022, 43, 2443–2452.
Xia, D. S.; Tang, X.; Dai, S.; Ge, R. L.; Rykov, A.; Wang, J. H.; Huang, T. H.; Wang, K. W.; Wei, Y. P.; Zhang, K. et al. Ultrastable Fe-N-C fuel cell electrocatalysts by eliminating non-coordinating nitrogen and regulating coordination structures at high temperatures. Adv. Mater. 2022, 35, 2204474.
Zhang, M. T.; Li, H.; Chen, J. X.; Ma, F. X.; Zhen, L.; Wen, Z. H.; Xu, C. Y. High-loading Co single atoms and clusters active sites toward enhanced electrocatalysis of oxygen reduction reaction for high-performance Zn-air battery. Adv. Funct. Mater. 2023, 33, 2209726.
Jiao, L.; Wan, G.; Zhang, R.; Zhou, H.; Yu, S. H.; Jiang, H. L. From metal-organic frameworks to single-atom Fe implanted N-doped porous carbons: Efficient oxygen reduction in both alkaline and acidic media. Angew. Chem. , Int. Ed. 2018, 57, 8525–8529.
Han, X. P.; Ling, X. F.; Wang, Y.; Ma, T. Y.; Zhong, C.; Hu, W. B.; Deng, Y. D. Generation of nanoparticle, atomic-cluster, and single-atom cobalt catalysts from zeolitic imidazole frameworks by spatial isolation and their use in zinc-air batteries. Angew. Chem. , Int. Ed. 2019, 58, 5359–5364.
Nie, Y.; Li, L.; Wei, Z. D. Recent advancements in Pt and Pt-free catalysts for oxygen reduction reaction. Chem. Soc. Rev. 2015, 44, 2168–2201.
Koper, M. T. M. Theory of multiple proton-electron transfer reactions and its implications for electrocatalysis. Chem. Sci. 2013, 4, 2710–2723.
Xiao, M. L.; Chen, Y. T.; Zhu, J. B.; Zhang, H.; Zhao, X.; Gao, L. Q.; Wang, X.; Zhao, J.; Ge, J. J.; Jiang, Z. et al. Climbing the apex of the ORR volcano plot via binuclear site construction: Electronic and geometric engineering. J. Am. Chem. Soc. 2019, 141, 17763–17770.
Wang, Y. Y.; Li, Z. G.; Zhang, P.; Pan, Y.; Zhang, Y.; Cai, Q.; Silva, S. R. P.; Liu, J.; Zhang, G. X.; Sun, X. M. et al. Flexible carbon nanofiber film with diatomic Fe-Co sites for efficient oxygen reduction and evolution reactions in wearable zinc-air batteries. Nano Energy 2021, 87, 106147.
Liu, D.; Wang, B.; Li, H.; Huang, S.; Wang, Q.; Wang, J.; Liu, M.; Zhang, J.; Zhao, Y. Zn,Co-Nx-C-Sy active sites confined in dentric carbon for highly efficient oxygen reduction reaction and flexible Zn-air batteries. Nano Energy 2019, 58, 277–283.
Li, H. X.; Wen, Y. L.; Jiang, M.; Yao, Y.; Zhou, H. H.; Huang, Z. Y.; Li, J. W.; Jiao, S. Q.; Kuang, Y. F.; Luo, S. L. Understanding of neighboring Fe-N4-C and Co-N4-C dual active centers for oxygen reduction reaction. Adv. Funct. Mater. 2021, 31, 2011289.
Cui, T. T.; Wang, Y. P.; Ye, T.; Wu, J.; Chen, Z. Q.; Li, J.; Lei, Y. P.; Wang, D. S.; Li, Y. D. Engineering dual single-atom sites on 2D ultrathin N-doped carbon nanosheets attaining ultra-low-temperature Zinc-Air battery. Angew. Chem., Int. Ed. 2022, 61, e202115219.
Zhang, N.; Zhou, T. P.; Ge, J. K.; Lin, Y.; Du, Z. Y.; Zhong, C. A.; Wang, W. J.; Jiao, Q. Y.; Yuan, R. L.; Tian, Y. C. et al. High-density planar-like Fe2N6 structure catalyzes efficient oxygen reduction. Matter 2020, 3, 509–521.
Wu, J. B.; Xiong, L. K.; Zhao, B. T.; Liu, M. L.; Huang, L. Densely populated single atom catalysts. Small Methods 2020, 4, 1900540.
Wu, J. B.; Zhou, H.; Li, Q.; Chen, M.; Wan, J.; Zhang, N.; Xiong, L. K.; Li, S.; Xia, B. Y.; Feng, G. et al. Densely populated isolated single Co-N site for efficient oxygen electrocatalysis. Adv. Energy Mater. 2019, 9, 1900149.
Ji, D. X.; Fan, L.; Li, L. L.; Peng, S. J.; Yu, D. S.; Song, J. N.; Ramakrishna, S.; Guo, S. J. Atomically transition metals on self-supported porous carbon flake arrays as binder-free air cathode for wearable zinc-air batteries. Adv. Mater. 2019, 31, 1808267.
Zhao, L.; Zhang, Y.; Huang, L. B.; Liu, X. Z.; Zhang, Q. H.; He, C.; Wu, Z. Y.; Zhang, L. J.; Wu, J. P.; Yang, W. L. et al. Cascade anchoring strategy for general mass production of high-loading single-atomic metal-nitrogen catalysts. Nat. Commun. 2019, 10, 1278.
Li, J.; Chen, S. G.; Yang, N.; Deng, M. M.; Ibraheem, S.; Deng, J. H.; Li, J.; Li, L.; Wei, Z. D. Ultrahigh-loading zinc single-atom catalyst for highly efficient oxygen reduction in both acidic and alkaline media. Angew. Chem. , Int. Ed. 2019, 58, 7035–7039.
Xia, C.; Qiu, Y. R.; Xia, Y.; Zhu, P.; King, G.; Zhang, X.; Wu, Z. Y.; Kim, J. Y.; Cullen, D. A.; Zheng, D. X. et al. General synthesis of single-atom catalysts with high metal loading using graphene quantum dots. Nat. Chem. 2021, 13, 887–894.
Jing, T. Y.; Li, T. T.; Rao, D. W.; Wang, M. Y.; Zuo, Y. P. Defining the loading of single-atom catalysts: Weight fraction or atomic fraction? Mater. Today Energy 2023, 31, 101197.
Xie, X. Y.; Peng, L. S.; Yang, H. Z.; Waterhouse, G. I. N.; Shang, L.; Zhang, T. R. MIL-101-derived mesoporous carbon supporting highly exposed Fe single-atom sites as efficient oxygen reduction reaction catalysts. Adv. Mater. 2021, 33, 2101038.
Tang, X. N.; Wei, Y. H.; Zhai, W. J.; Wu, Y. G.; Hu, T.; Yuan, K.; Chen, Y. W. Carbon nanocage with maximum utilization of atomically dispersed iron as efficient oxygen electroreduction nanoreactor. Adv. Mater. 2023, 35, 2208942.
Li, Z. J.; Ji, S. Q.; Xu, C.; Leng, L. P.; Liu, H. X.; Horton, J. H.; Du, L.; Gao, J. C.; He, C.; Qi, X. Y. et al. Engineering the electronic structure of single atom iron sites with boosted oxygen bifunctional activity for Zinc-Air batteries. Adv. Mater. 2023, 35, 2209644.
Zhu, Z. J.; Yin, H. J.; Wang, Y.; Chuang, C. H.; Xing, L.; Dong, M. Y.; Lu, Y. R.; Casillas-Garcia, G.; Zheng, Y. L.; Chen, S. et al. Coexisting single-atomic Fe and Ni sites on hierarchically ordered porous carbon as a highly efficient ORR electrocatalyst. Adv. Mater. 2020, 32, 2004670.
Zhou, Y.; Yu, Y. N.; Ma, D. S.; Foucher, A. C.; Xiong, L.; Zhang, J. H.; Stach, E. A.; Yue, Q.; Kang, Y. J. Atomic Fe dispersed hierarchical mesoporous Fe-N-C nanostructures for an efficient oxygen reduction reaction. ACS Catal. 2021, 11, 74–81.
Jung, J. Y.; Kim, S.; Kim, J. G.; Kim, M. J.; Lee, K. S.; Sung, Y. E.; Kim, P.; Yoo, S. J.; Lim, H. K.; Kim, N. D. Hierarchical porous single-wall carbon nanohorns with atomic-level designed single-atom Co sites toward oxygen reduction reaction. Nano Energy 2022, 97, 107206.
Zhao, Y. F.; Jiang, W. J.; Zhang, J. Q.; Lovell, E. C.; Amal, R.; Han, Z. J.; Lu, X. Y. Anchoring sites engineering in single-atom catalysts for highly efficient electrochemical energy conversion reactions. Adv. Mater. 2021, 33, 2102801.
Noh, W. Y.; Mun, J.; Lee, Y.; Kim, E. M.; Kim, Y. K.; Kim, K. Y.; Jeong, H. Y.; Lee, J. H.; Song, H. K.; Lee, G. et al. Molecularly engineered carbon platform to anchor edge-hosted single-atomic M-N/C (M = Fe, Co, Ni, Cu) electrocatalysts of outstanding durability. ACS Catal. 2022, 12, 7994–8006.
Jiang, R.; Li, L.; Sheng, T.; Hu, G. F.; Chen, Y. G.; Wang, L. Y. Edge-site engineering of atomically dispersed Fe-N4 by selective C-N bond cleavage for enhanced oxygen reduction reaction activities. J. Am. Chem. Soc. 2018, 140, 11594–11598.
Fu, X. G.; Li, N.; Ren, B. H.; Jiang, G. P.; Liu, Y. R.; Hassan, F. M.; Su, D.; Zhu, J. B.; Yang, L.; Bai, Z. Y. et al. Tailoring FeN4 sites with edge enrichment for boosted oxygen reduction performance in proton exchange membrane fuel cell. Adv. Energy Mater. 2019, 9, 1803737.
Carr, L. D.; Lusk, M. T. Graphene gets designer defects. Nat. Nanotechnol. 2010, 5, 316–317.
Kim, Y.; Ihm, J.; Yoon, E.; Lee, G. D. Dynamics and stability of divacancy defects in graphene. Phys. Rev. B 2011, 84, 075445.
Yang, Q.; Jia, Y.; Wei, F. F.; Zhuang, L. Z.; Yang, D. J.; Liu, J. Z.; Wang, X.; Lin, S.; Yuan, P.; Yao, X. D. Understanding the activity of Co-N4−xCx in atomic metal catalysts for oxygen reduction catalysis. Angew. Chem. , Int. Ed. 2020, 59, 6122–6127.
Zong, L. B.; Fan, K. C.; Wu, W. C.; Cui, L. X.; Zhang, L. L.; Johannessen, B.; Qi, D. C.; Yin, H. J.; Wang, Y.; Liu, P. R. et al. Anchoring single copper atoms to microporous carbon spheres as high-performance electrocatalyst for oxygen reduction reaction. Adv. Funct. Mater. 2021, 31, 2104864.
Ramaswamy, N.; Tylus, U.; Jia, Q. Y.; Mukerjee, S. Activity descriptor identification for oxygen reduction on nonprecious electrocatalysts: Linking surface science to coordination chemistry. J. Am. Chem. Soc. 2013, 135, 15443–15449.
Liu, K.; Fu, J. W.; Lin, Y. Y.; Luo, T.; Ni, G. H.; Li, H. M.; Lin, Z.; Liu, M. Insights into the activity of single-atom Fe-N-C catalysts for oxygen reduction reaction. Nat. Commun. 2022, 13, 2075.
Wang, X.; Jia, Y.; Mao, X.; Liu, D. B.; He, W. X.; Li, J.; Liu, J. G.; Yan, X. C.; Chen, J.; Song, L. et al. Edge-rich Fe-N4 active sites in defective carbon for oxygen reduction catalysis. Adv. Mater. 2020, 32, 2000966.
Chen, Y. J.; Ji, S. F.; Zhao, S.; Chen, W. X.; Dong, J. C.; Cheong, W. C.; Shen, R. A.; Wen, X. D.; Zheng, L. R.; Rykov, A. I. et al. Enhanced oxygen reduction with single-atomic-site iron catalysts for a zinc-air battery and hydrogen-air fuel cell. Nat. Commun. 2018, 9, 5422.
Zhang, T. Y.; Wang, F. P.; Yang, C.; Han, X.; Liang, C.; Zhang, Z. D.; Li, Y. P.; Han, A. J.; Liu, J. F.; Liu, B. Boosting ORR performance by single atomic divacancy Zn-N3C-C8 sites on ultrathin N-doped carbon nanosheets. Chem Catal. 2022, 2, 836–852.
Wang, L. X.; Wang, J.; Gao, X. P.; Chen, C.; Da, Y. L.; Wang, S. C.; Yang, J.; Wang, Z. Y.; Song, J.; Yao, T. et al. Periodic one-dimensional single-atom arrays. J. Am. Chem. Soc. 2022, 144, 15999–16005.
Lu, Z. Y.; Wang, B.; Hu, Y. F.; Liu, W.; Zhao, Y. F.; Yang, R. O.; Li, Z. P.; Luo, J.; Chi, B.; Jiang, Z. et al. An isolated zinc-cobalt atomic pair for highly active and durable oxygen reduction. Angew. Chem. , Int. Ed. 2019, 58, 2622–2626.
Tian, H.; Song, A. L.; Zhang, P.; Sun, K. A.; Wang, J. J.; Sun, B.; Fan, Q. H.; Shao, G. J.; Chen, C.; Liu, H. et al. High durability of Fe-N-C single-atom catalysts with carbon vacancies toward the oxygen reduction reaction in alkaline media. Adv. Mater. 2023, 35, 2210714.
Chi, B.; Zhang, L. H.; Yang, X. X.; Zeng, Y. C.; Deng, Y. J.; Liu, M. R.; Huo, J. L.; Li, C. Z.; Zhang, X. R.; Shi, X. D. et al. Promoting ZIF-8-derived Fe-N-C oxygen reduction catalysts via Zr doping in proton exchange membrane fuel cells: Durability and activity enhancements. ACS Catal. 2023, 13, 4221–4230.
Cheng, W. R.; Zhao, X.; Su, H.; Tang, F. M.; Che, W.; Zhang, H.; Liu, Q. H. Lattice-strained metal-organic-framework arrays for bifunctional oxygen electrocatalysis. Nat. Energy 2019, 4, 115–122.
Wei, J.; Xia, D. S.; Wei, Y. P.; Zhu, X. Y.; Li, J.; Gan, L. Probing the oxygen reduction reaction intermediates and dynamic active site structures of molecular and pyrolyzed Fe-N-C electrocatalysts by in situ Raman spectroscopy. ACS Catal. 2022, 12, 7811–7820.
Li, X. N.; Cao, C. S.; Hung, S. F.; Lu, Y. R.; Cai, W. Z.; Rykov, A. I.; Miao, S.; Xi, S. B.; Yang, H. B.; Hu, Z. H. et al. Identification of the electronic and structural dynamics of catalytic centers in single-Fe-atom material. Chem 2020, 6, 3440–3454.
Wei, C.; Rao, R. R.; Peng, J. Y.; Huang, B. T.; Stephens, I. E. L.; Risch, M.; Xu, Z. J.; Shao-Horn, Y. Recommended practices and benchmark activity for hydrogen and oxygen electrocatalysis in water splitting and fuel cells. Adv. Mater. 2019, 31, 1806296.
The articles published in this open access journal are distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits use, distribution and reproduction in any medium, provided the original work is properly cited.