Metal-organic framework-based single-atom electro-/photocatalysts: Synthesis, energy applications, and opportunities

Abstract

Single-atom catalysts (SACs) have gained substantial attention because of their exceptional catalytic properties. However, the high surface energy limits their synthesis, thus creating significant challenges for further development. In the last few years, metal-organic frameworks (MOFs) have received significant consideration as ideal candidates for synthesizing SACs due to their tailorable chemistry, tunable morphologies, high porosity, and chemical/thermal stability. From this perspective, this review thoroughly summarizes the previously reported methods and possible future approaches for constructing MOF-based (MOF-derived-supported and MOF-supported) SACs. Then, MOF-based SAC's identification techniques are briefly assessed to understand their coordination environments, local electronic structures, spatial distributions, and catalytic/electrochemical reaction mechanisms. This review systematically highlights several photocatalytic and electrocatalytic applications of MOF-based SACs for energy conversion and storage, including hydrogen evolution reactions, oxygen evolution reactions, O₂/CO₂/N₂ reduction reactions, fuel cells, and rechargeable batteries. Some light is also shed on the future development of this highly exciting field by highlighting the advantages and limitations of MOF-based SACs.

Keywords

carbon / energy generation / MOF-derived-supported / MOF-supported / single atoms

References

[1] Dunn B, Kamath H, Tarascon JM. Electrical energy storage for the grid: a battery of choices. Science. 2011; 334 (6058): 928- 935.

[2] Seh ZW, Kibsgaard J, Dickens CF, Chorkendorff I, Nørskov JK, Jaramillo TF. Combining theory and experiment in electrocatalysis: insights into materials design. Science. 2017; 355 (6321): 4998.

[3] Su J, Ge R, Dong Y, Hao F, Chen L. Recent progress in singleatom electrocatalysts: concept, synthesis, and applications in clean energy conversion. J Mater Chem A. 2018; 6 (29): 14025- 14042.

[4] Ahmad M, Quan X, Chen S, Yu H, Zeng Z. Operating redox couple transport mechanism for enhancing photocatalytic H₂ generation of Pt and CrOx-decorated ZnCdS nanocrystals. Appl Catal B. 2021; 283: 119601.

[5] Sun T, Xu L, Yan Y, Zakhidov AA, Baughman RH, Chen J. Ordered mesoporous nickel sphere arrays for highly efficient electrocatalytic water oxidation. ACS Catal. 2016; 6 (3): 1446- 1450.

[6] Tang T, Jiang W-J, Niu S, et al. Electronic and morphological dual modulation of cobalt carbonate hydroxides by Mn doping toward highly efficient and stable bifunctional electrocatalysts for overall water splitting. J Am Chem Soc. 2017; 139 (24): 8320- 8328.

[7] Long B, Tang Y, Li J. New mechanistic pathways for CO oxidation catalyzed by single atom catalysts: supported and doped Au₁/ThO₂. Nano Res. 2016; 9 (12): 3868- 3880.

[8] Liu J. Catalysis by supported single metal atoms. ACS Catal. 2017; 7 (1): 34- 59.

[9] Zhu C, Fu S, Shi Q, Du D, Lin Y. Single-atom electrocatalysts. Angew Chem Int Ed. 2017; 56 (45): 13944- 13960.

[10] Qiao B, Wang A, Yang X, et al. Single-atom catalysis of CO oxidation using Pt₁/FeO_x. Nat Chem. 2011; 3 (8): 634- 641.

[11] Yang X-F, Wang A, Qiao B, Li J, Liu J, Zhang T. Single-atom catalysts: a new frontier in heterogeneous catalysis. Acc Chem Res. 2013; 46 (8): 1740- 1748.

[12] Qin R, Liu P, Fu G, Zheng N. Strategies for stabilizing atomically dispersed metal catalysts. Small Methods. 2018; 2 (1): 1700286.

[13] Dang S, Zhu Q-L, Xu Q. Nanomaterials derived from metalorganic frameworks. Nat Rev Mater. 2018; 3 (1): 17075.

[14] Howarth AJ, Peters AW, Vermeulen NA, Wang TC, Hupp JT, Farha OK. Best practices for the synthesis, activation, and characterization of metal-organic frameworks. Chem Mater. 2017; 29 (1): 26- 39.

[15] Liu B, Shioyama H, Akita T, Xu Q. Metal-organic framework as a template for porous carbon synthesis. J Am Chem Soc. 2008; 130 (16): 5390- 5391.

[16] Ahn SH, Yu X, Manthiram A. “Wiring” Fe-N_x-embedded porous carbon framework onto 1D nanotubes for efficient oxygen reduction reaction in alkaline and acidic media. Adv Mater. 2017; 29 (26): 1606534.

[17] Chong L, Wen J, Kubal J, et al. Ultralow-loading platinum-cobalt fuel cell catalysts derived from imidazolate frameworks. Science. 2018; 362 (6420): 1276- 1281.

[18] Li F, Han G-F, Noh H-J, et al. Boosting oxygen reduction catalysis with abundant copper single atom active sites. Energy Environ Sci. 2018; 11 (8): 2263- 2269.

[19] Kaneti YV, Tang J, Salunkhe RR, et al. Nanoarchitectured design of porous materials and nanocomposites from metalorganic frameworks. Adv Mater. 2017; 29 (12): 1604898.

[20] Liu L, Corma A. Metal catalysts for heterogeneous catalysis: from single atoms to nanoclusters and nanoparticles. Chem Rev. 2018; 118 (10): 4981- 5079.

[21] Hülsey MJ, Zhang J, Yan N. Harnessing the wisdom in colloidal chemistry to make stable single-atom catalysts. Adv Mater. 2018; 30 (47): 1802304.

[22] Gao C, Chen S, Wang Y, et al. Heterogeneous single-atom catalyst for visible-light driven high-turnover CO₂ reduction: the role of electron transfer. Adv Mater. 2018; 30 (13): 1704624.

[23] Wang J, Li Z, Wu Y, Li Y. Fabrication of single-atom catalysts with precise structure and high metal loading. Adv Mater. 2018; 30 (48): 1801649.

[24] Shen K, Chen X, Chen J, Li Y. Development of MOF-derived carbon-based nanomaterials for efficient catalysis. ACS Catal. 2016; 6 (9): 5887- 5903.

[25] Wang H-F, Chen L, Pang H, Kaskel S, Xu Q. MOF-derived electrocatalysts for oxygen reduction, oxygen evolution and hydrogen evolution reactions. Chem Soc Rev. 2020; 49 (5): 1414- 1448.

[26] Wang T, Cao X, Jiao L. MOFs-derived carbon-based metal catalysts for energy-related electrocatalysis. Small. 2021; 17 (22): 2004398.

[27] Wei Y-S, Zhang M, Zou R, Xu Q. Metal-organic frameworkbased catalysts with single metal sites. Chem Rev. 2020; 120 (21): 12089- 12174.

[28] Ahmad M, Chen S, Ye F, et al. Efficient photo-Fenton activity in mesoporous MIL-100 (Fe) decorated with ZnO nanosphere for pollutants degradation. Appl Catal B. 2019; 245: 428- 438.

[29] Ahmad M, Quan X, Chen S, Yu H. Tuning Lewis acidity of MIL-88B-Fe with mix-valence coordinatively unsaturated iron centers on ultrathin Ti₃C₂ nanosheets for efficient photo Fenton reaction. Appl Catal B. 2020; 264: 118534.

[30] Gu Z-G, Li D-J, Zheng C, Kang Y, Wöll C, Zhang J. MOF-templated synthesis of ultrasmall photoluminescent carbonnanodot arrays for optical applications. Angew Chem Int Ed. 2017; 56 (24): 6853- 6858.

[31] Li Z, Shao M, Zhou L, et al. Carbon-based electrocatalyst derived from bimetallic metal organic framework arrays for high performance oxygen reduction. Nano Energy. 2016; 25: 100- 109.

[32] Chaudhari KN, Song MY, Yu J-S. Transforming hair into heteroatom-doped carbon with high surface area. Small. 2014; 10 (13): 2625- 2636.

[33] Zhang P, Sun F, Xiang Z, Shen Z, Yun J, Cao D. ZIF-derived in situ nitrogen-doped porous carbons as efficient metal-free electrocatalysts for oxygen reduction reaction. Energy Environ Sci. 2014; 7 (1): 442- 450.

[34] Wei J, Hu Y, Liang Y, et al. Nitrogen-doped nanoporous carbon/graphene nano sandwiches: synthesis and application for efficient oxygen reduction. Adv Funct Mater. 2015; 25 (36): 5768- 5777.

[35] Li Q, Xu P, Gao W, et al. Graphene/graphene-tube nanocomposites templated from cage-containing metalorganic frameworks for oxygen reduction in Li-O₂ batteries. Adv Mater. 2014; 26 (9): 1378- 1386.

[36] Jiao L, Jiang H-L. Metal-organic-framework-based single-atom catalysts for energy applications. Chem. 2019; 5 (4): 786- 804.

[37] Zhang J, Wu X, Cheong W-C, et al. Cation vacancy stabilization of single-atomic-site Pt₁/Ni(OH)_x catalyst for diboration of alkynes and alkenes. Nat Commun. 2018; 9: 1002.

[38] Sun S, Zhang G, Gauquelin N, et al. Single-atom catalysis using Pt/graphene achieved through atomic layer deposition. Sci Rep. 2013; 3 (1): 1775.

[39] Piernavieja-Hermida M, Lu Z, White A, et al. Towards ALD thin film stabilized single atom Pd-1 catalysts. Nanoscale. 2016; 8 (33): 15348- 15356.

[40] Liu P, Zhao Y, Qin R, et al. Photochemical route for synthesizing atomically dispersed palladium catalysts. Science. 2016; 352 (6287): 797- 800.

[41] Wang XX, Cullen DA, Pan Y-T, et al. Nitrogen-coordinated single cobalt atom catalysts for oxygen reduction in proton exchange membrane fuel cells. Adv Mater. 2018; 30 (11): 1706758.

[42] Yin P, Yao T, Wu Y, et al. Single cobalt atoms with precise N-coordination as superior oxygen reduction reaction catalysts. Angew Chem Int Ed. 2016; 55 (36): 10800- 10805.

[43] Wang X, Chen Z, Zhao X, et al. Regulation of coordination number over single co sites: triggering the efficient electroreduction of CO₂. Angew Chem Int Ed. 2018; 57 (7): 1944- 1948.

[44] Zhou Y, Chen G, Wang Q, et al. Fe-N-C electrocatalysts with densely accessible Fe-N₄ sites for efficient oxygen reduction reaction. Adv Funct Mater. 2021; 31 (34): 2102420.

[45] Zhao C, Dai X, Yao T, et al. Ionic exchange of metal organic frameworks to access single nickel sites for efficient electroreduction of CO₂. J Am Chem Soc. 2017; 139 (24): 8078- 8081.

[46] Chen Y, Ji S, Zhao S, 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.

[47] Klet RC, Wang TC, Fernandez LE, Truhlar DG, Hupp JT, Farha OK. Synthetic access to atomically dispersed metals in metal-organic frameworks via a combined atomic layer deposition-in-MOF and metal-exchange approach. Chem Mater. 2016; 28 (4): 1213- 1219.

[48] Wang X, Chen W, Zhang L, et al. Uncoordinated amine groups of metal-organic frameworks to anchor single Ru sites as chemoselective catalysts toward the hydrogenation of quinoline. J Am Chem Soc. 2017; 139 (28): 9419- 9422.

[49] Chen Y, Ji S, Wang Y, et al. Isolated single iron atoms anchored on N-doped porous carbon as an efficient electrocatalyst for the oxygen reduction reaction. Angew Chem. 2017; 129 (24): 7041- 7045.

[50] Han J, Meng X, Lu L, Bian J, Li Z, Sun C. Single-atom Fe-N_x-C as an efficient electrocatalyst for zinc-air batteries. Adv Funct Mater. 2019; 29 (41): 1808872.

[51] Wei S, Li A, Liu J-C, et al. Direct observation of noble metal nanoparticles transforming to thermally stable single atoms. Nat Nanotechnol. 2018; 13 (9): 856- 861.

[52] Jones J, Xiong H, DeLaRiva AT, et al. Thermally stable single-atom platinum-on-ceria catalysts via atom trapping. Science. 2016; 353 (6295): 150- 154.

[53] Yang J, Qiu Z, Zhao C, et al. In situ thermal atomization to convert supported nickel nanoparticles into surface-bound nickel single-atom catalysts. Angew Chem Int Ed. 2018; 57 (43): 14095- 14100.

[54] Qu Y, Li Z, Chen W, et al. Direct transformation of bulk copper into copper single sites via emitting and trapping of atoms. Nat Catal. 2018; 1 (10): 781- 786.

[55] Zheng X, Li P, Dou S, et al. Non-carbon-supported singleatom site catalysts for electrocatalysis. Energy Environ Sci. 2021; 14 (5): 2809- 2858.

[56] Imahori H, Fukuzumi S. Porphyrin monolayer-modified gold clusters as photoactive materials. Adv Mater. 2001; 13 (15): 1197- 1199.

[57] Zhang Z, Zhu Y, Chen X, Zhang H, Wang J. A full-spectrum metal-free porphyrin supramolecular photocatalyst for dual functions of highly efficient hydrogen and oxygen evolution. Adv Mater. 2019; 31 (7): 1806626.

[58] Johnson JA, Luo J, Zhang X, et al. Porphyrin-metalationmediated tuning of photoredox catalytic properties in metal-organic frameworks. ACS Catal. 2015; 5 (9): 5283- 5291.

[59] Cai P, Xu M, Meng SS, et al. Precise spatial-designed metal-organic-framework nanosheets for efficient energy transfer and photocatalysis. Angew Chem. 2021; 133 (52): 27464- 27469.

[60] Fang X, Shang Q, Wang Y, et al. Single Pt atoms confined into a metal-organic framework for efficient photocatalysis. Adv Mater. 2018; 30 (7): 1705112.

[61] He T, Chen S, Ni B, et al. Zirconium-porphyrin-based metal-organic framework hollow nanotubes for immobilization of noble-metal single atoms. Angew Chem. 2018; 130 (13): 3551- 3556.

[62] Wang Z, Cohen SM. Postsynthetic modification of metal-organic frameworks. Chem Soc Rev. 2009; 38 (5): 1315- 1329.

[63] Abedi S, Morsali A. Improved activity of palladium nanoparticles using a sulfur-containing metal.organic framework as an efficient catalyst for selective aerobic oxidation in water. New J Chem. 2017; 41 (13): 5846- 5852.

[64] Ji S, Chen Y, Zhao S, et al. Atomically dispersed ruthenium species inside metal.organic frameworks: combining the high activity of atomic sites and the molecular sieving effect of MOFs. Angew Chem. 2019; 131 (13): 4315- 4319.

[65] Islamoglu T, Goswami S, Li Z, Howarth AJ, Farha OK, Hupp JT. Postsynthetic tuning of metal.organic frameworks for targeted applications. Acc Chem Res. 2017; 50 (4): 805- 813.

[66] Otake K, Cui Y, Buru CT, Li Z, Hupp JT, Farha OK. Single-atom-based vanadium oxide catalysts supported on metal.organic frameworks: selective alcohol oxidation and structure.activity relationship. J Am Chem Soc. 2018; 140 (28): 8652- 8656.

[67] Lucci FR, Liu J, Marcinkowski MD, et al. Selective hydrogenation of 1, 3-butadiene on platinum.copper alloys at the single-atom limit. Nat Commun. 2015; 6: 8550.

[68] Ji P, Song Y, Drake T, et al. Titanium (III)-oxo clusters in a metal.organic framework support single-site Co(II)-hydride catalysts for arene hydrogenation. J Am Chem Soc. 2018; 140 (1): 433- 440.

[69] Cheng N, Stambula S, Wang D, et al. Platinum single-atom and cluster catalysis of the hydrogen evolution reaction. Nat Commun. 2016; 7: 13638.

[70] Peng Y, Huang H, Zhang Y, et al. A versatile MOF-based trap for heavy metal ion capture and dispersion. Nat Commun. 2018; 9: 187.

[71] Li Z, Schweitzer NM, League AB, et al. Sintering-resistant single-site nickel catalyst supported by metal.organic framework. J Am Chem Soc. 2016; 138 (6): 1977- 1982.

[72] Abdel-Mageed AM, Rungtaweevoranit B, Parlinska-Wojtan M, Pei X, Yaghi OM, Behm RJ. Highly active and stable single-atom Cu catalysts supported by a metal-organic framework. J Am Chem Soc. 2019; 141 (13): 5201- 5210.

[73] Yao Y, Huang Z, Xie P, et al. High temperature shockwave stabilized single atoms. Nat Nanotechnol. 2019; 14 (9): 851- 857.

[74] Chang T-Y, Tanaka Y, Ishikawa R, et al. Direct imaging of Pt single atoms adsorbed on TiO₂ (110) surfaces. Nano Lett. 2014; 14 (1): 134- 138.

[75] Jiao L, Wan G, Zhang R, Zhou H, Yu SH, Jiang HL. 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 (28): 8525- 8529.

[76] Fei H, Dong J, Feng Y, et al. General synthesis and definitive structural identification of MN₄C₄ single-atom catalysts with tunable electrocatalytic activities. Nat Catal. 2018; 1 (1): 63- 72.

[77] Zhang L, Si R, Liu H, et al. Author correction: atomic layer deposited Pt.Ru dual-metal dimers and identifying their active sites for hydrogen evolution reaction. Nat Commun. 2019; 10: 5453.

[78] Frenkel AI. Applications of extended X-ray absorption finestructure spectroscopy to studies of bimetallic nanoparticle catalysts. Chem Soc Rev. 2012; 41 (24): 8163- 8178.

[79] Xiao M, Zhu J, Ma L, et al. Microporous framework induced synthesis of single-atom dispersed Fe-NC acidic ORR catalyst and its in situ reduced Fe-N₄ active site identification revealed by X-ray absorption spectroscopy. ACS Catal. 2018; 8 (4): 2824- 2832.

[80] Yang HB, Hung S-F, Liu S, et al. Atomically dispersed Ni (I) as the active site for electrochemical CO₂ reduction. Nat Energy. 2018; 3 (2): 140- 147.

[81] Jia Q, Ramaswamy N, Hafiz H, et al. Experimental observation of redox-induced Fe.N switching behavior as a determinant role for oxygen reduction activity. ACS Nano. 2015; 9 (12): 12496- 12505.

[82] Li X, Yang X, Zhang J, Huang Y, Liu B. In situ/operando techniques for characterization of single-atom catalysts. ACS Catal. 2019; 9 (3): 2521- 2531.

[83] Nguyen L, Zhang S, Wang L, et al. Reduction of nitric oxide with hydrogen on catalysts of singly dispersed bimetallic sites Pt₁Co_m and Pd₁Co_n. ACS Catal. 2016; 6 (2): 840- 850.

[84] Bruix A, Lykhach Y, Matolinova I, et al. Maximum noblemetal efficiency in catalytic materials: atomically dispersed surface platinum. Angew Chem Int Ed. 2014; 53 (39): 10525- 10530.

[85] Kottwitz M, Li Y, Palomino RM, et al. Local structure and electronic state of atomically dispersed Pt supported on nanosized CeO₂. ACS Catal. 2019; 9 (9): 8738- 8748.

[86] Vile G, Albani D, Nachtegaal M, et al. A stable single-site palladium catalyst for hydrogenations. Angew Chem Int Ed. 2015; 54 (38): 11265- 11269.

[87] Nie L, Mei D, Xiong H, et al. Activation of surface lattice oxygen in single-atom Pt/CeO₂ for low-temperature CO oxidation. Science. 2017; 358 (6369): 1419- 1423.

[88] DeRita L, Dai S, Lopez-Zepeda K, et al. Catalyst architecture for stable single atom dispersion enables site-specific spectroscopic and reactivity measurements of CO adsorbed to Pt atoms, oxidized Pt clusters, and metallic Pt clusters on TiO₂. J Am Chem Soc. 2017; 139 (40): 14150- 14165.

[89] Happel M, Mysliveček J, Johánek V, et al. Adsorption sites, metal-support interactions, and oxygen spillover identified by vibrational spectroscopy of adsorbed CO: a model study on Pt/ceria catalysts. J Catal. 2012; 289 (5): 118- 126.

[90] Li J, Zhang H, Samarakoon W, et al. Thermally driven structure and performance evolution of atomically dispersed FeN₄ sites for oxygen reduction. Angew Chem. 2019; 131 (52): 19147- 19156.

[91] Lang R, Xi W, Liu J-C, et al. Non defect-stabilized thermally stable single-atom catalyst. Nat Commun. 2019; 10: 234.

[92] Kwak JH, Hu J, Mei D, et al. Coordinatively unsaturated Al³⁺ centers as binding sites for active catalyst phases of platinum on γ-Al₂O₃. Science. 2009; 325 (5948): 1670- 1673.

[93] Xu X, Luo G, Mehmood A, et al. Theoretical mechanistic studies on redox-switchable polymerization of trimethylene carbonate catalyzed by an indium complex bearing a ferrocene-based ligand. Organometallics. 2018; 37 (24): 4599- 4607.

[94] Mehmood A, Xu X, Raza W, Kukkar D, Kim K-H, Luo Y. Computational study of the copolymerization mechanism of ethylene with methyl 2-acetamidoacrylate catalyzed by phosphine-sulfonate palladium complexes. New J Chem. 2021; 45 (36): 16670- 16678.

[95] Mehmood A, Xu X, Raza W, Kim K-H, Luo Y. Mechanistic studies for palladium catalyzed copolymerization of ethylene with vinyl ethers. Polymers. 2020; 12 (10): 2401.

[96] Shi Y, Fu J, Hui K, et al. Promoting the electrochemical properties of yolk-shell-structured CeO2 composites for lithium-ion batteries. Microstructure. 2021; 1 (1): 2021005.

[97] Corma A, Salnikov OG, Barskiy DA, Kovtunov KV, Koptyug IV. Single-atom gold catalysis in the context of developments in parahydrogen-induced polarization. Chem Eur J. 2015; 21 (19): 7012- 7015.

[98] Dhakshinamoorthy A, Asiri AM, García H. Metal-organic framework (MOF) compounds: photocatalysts for redox reactions and solar fuel production. Angew Chem Int Ed. 2016; 55 (18): 5414- 5445.

[99] Zhang H, Wei J, Dong J, et al. Efficient visible-light-driven carbon dioxide reduction by a single-atom implanted metal-organic framework. Angew Chem. 2016; 128 (46): 14522- 14526.

[100] Hao Y-C, Chen L-W, Li J, et al. Metal-organic framework membranes with single-atomic centers for photocatalytic CO₂ and O₂ reduction. Nat Commun. 2021; 12: 2682.

[101] Ma X, Liu H, Yang W, Mao G, Zheng L, Jiang H-L. Modulating coordination environment of single-atom catalysts and their proximity to photosensitive units for boosting MOF photocatalysis. J Am Chem Soc. 2021; 143 (31): 12220- 12229.

[102] Wang G, He C-T, Huang R, Mao J, Wang D, Li Y. Photoinduction of Cu single atoms decorated on UiO-66-NH₂ for enhanced photocatalytic reduction of CO₂ to liquid fuels. J Am Chem Soc. 2020; 142 (45): 19339- 19345.

[103] Dong P, Wang Y, Zhang A, Cheng T, Xi X, Zhang J. Platinum single atoms anchored on a covalent organic framework: boosting active sites for photocatalytic hydrogen evolution. ACS Catal. 2021; 11 (21): 13266- 13279.

[104] Li J, Huang H, Liu P, et al. Metal-organic framework encapsulated single-atom Pt catalysts for efficient photocatalytic hydrogen evolution. J Catal. 2019; 375: 351- 360.

[105] Fan L, Liu PF, Yan X, et al. Atomically isolated nickel species anchored on graphitized carbon for efficient hydrogen evolution electrocatalysis. Nat Commun. 2016; 7: 10667.

[106] Wan J, Zhao Z, Shang H, et al. In-situ phosphatizing of triphenylphosphine encapsulated within metal-organic frameworks to design atomic Co₁-P₁N₃ interfacial structure for promoting catalytic performance. J Am Chem Soc. 2020; 142 (18): 8431- 8439.

[107] Yin P, Yao T, Wu Y, et al. Single cobalt atoms with precise N-coordination as superior oxygen reduction reaction catalysts. Angew Chem. 2016; 128 (36): 10958- 10963.

[108] Ye Y, Li H, Cai F, et al. Two-dimensional mesoporous carbon doped with Fe-N active sites for efficient oxygen reduction. ACS Catal. 2017; 7 (11): 7638- 7646.

[109] Wu J, Zhou H, Li Q, et al. Densely populated isolated single Co-N site for efficient oxygen electrocatalysis. Adv Energy Mater. 2019; 9 (22): 1900149.

[110] Zou L, Wei Y-S, Hou C-C, et al. One-step synthesis of ultrathin carbon nanoribbons from metal-organic framework nanorods for oxygen reduction and zinc-air batteries. CCS Chem. 2022; 4 (1): 194- 204.

[111] Yan C, Li H, Ye Y, et al. Coordinatively unsaturated nickelnitrogen sites towards selective and high-rate CO₂ electroreduction. Energy Environ Sci. 2018; 11 (5): 1204- 1210.

[112] Pan F, Zhang H, Liu K, et al. Unveiling active sites of CO₂ reduction on nitrogen coordinated and atomically dispersed iron and cobalt catalysts. ACS Catal. 2018; 8 (4): 3116- 3122.

[113] Wang Y, Wang M, Zhang Z, et al. Phthalocyanine precursors to construct atomically dispersed iron electrocatalysts. ACS Catal. 2019; 9 (7): 6252- 6261.

[114] Zhang R, Jiao L, Yang W, Wan G, Jiang H-L. Single-atom catalysts templated by metal organic frameworks for electrochemical nitrogen reduction. J Mater Chem A. 2019; 7 (46): 26371- 26377.

[115] Deng Y, Chi B, Tian X, et al. g-C₃N₄ promoted MOF derived hollow carbon nanopolyhedra doped with high density/fraction of single Fe atoms as an ultra-high performance nonprecious catalyst towards acidic ORR and PEM fuel cells. J Mater Chem A. 2019; 7 (9): 5020- 5030.

[116] Wan X, Liu X, Li Y, et al. Fe-N-C electrocatalyst with dense active sites and efficient mass transport for high-performance proton exchange membrane fuel cells. Nat Catal. 2019; 2 (3): 259- 268.

[117] Liu Q, Li Y, Zheng L, et al. Sequential synthesis and activesite coordination principle of precious metal single-atom catalysts for oxygen reduction reaction and PEM fuel cells. Adv Energy Mater. 2020; 10 (20): 2000689.

[118] Xiong Y, Dong J, Huang Z-Q, et al. Single-atom Rh/N-doped carbon electrocatalyst for formic acid oxidation. Nat Nanotechnol. 2020; 15 (5): 390- 397.

[119] Liu H, Wang M-Q, Chen Z-Y, Chen H, Xu M-W, Bao S-J. Design and synthesis of Co N-C porous catalyst derived from metal organic complexes for highly effective ORR. Dalton Trans. 2017; 46 (45): 15646- 15650.

[120] Zang W, Sumboja A, Ma Y, et al. Single Co atoms anchored in porous N-doped carbon for efficient zinc-air battery cathodes. ACS Catal. 2018; 8 (10): 8961- 8969.

[121] Li Y, Lin S, Wang D, et al. Single atom array mimic on ultrathin MOF nanosheets boosts the safety and life of lithium-sulfur batteries. Adv Mater. 2020; 32 (8): 1906722.

[122] Xiao F, Wang H, Xu J, et al. Generating short-chain sulfur suitable for efficient sodium sulfur batteries via atomic copper sites on a N,O-codoped carbon composite. Adv Energy Mater. 2021; 11 (26): 2100989.

[123] Hu X, Luo G, Zhao Q, et al. Ru single atoms on N-doped carbon by spatial confinement and ionic substitution strategies for high-performance Li-O₂ batteries. J Am Chem Soc. 2020; 142 (39): 16776- 16786.

[124] Chen W, Pei J, He CT, et al. Single tungsten atoms supported on MOF-derived N-doped carbon for robust electrochemical hydrogen evolution. Adv Mater. 2018; 30 (30): 1800396.

[125] Sui J, Liu H, Hu S, et al. A general strategy to immobilize single-atom catalysts in metal-organic frameworks for enhanced photocatalysis. Adv Mater. 2022; 34 (6): 2109203.

[126] Tao H, Choi C, Ding L-X, et al. Nitrogen fixation by Ru single-atom electrocatalytic reduction. Chem. 2019; 5 (1): 204- 214.

[127] Qiao M, Wang Y, Wang Q, et al. Hierarchically ordered porous carbon with atomically dispersed FeN₄ for ultraefficient oxygen reduction reaction in proton-exchange membrane fuel cells. Angew Chem Int Ed. 2020; 59 (7): 2688- 2694.

[128] Wang Y, Mao J, Meng X, Yu L, Deng D, Bao X. Catalysis with two-dimensional materials confining single atoms: concept, design, and applications. Chem Rev. 2018; 119 (3): 1806- 1854.

[129] Zhang B, Fan T, Xie N, Nie G, Zhang H. Versatile applications of metal single-atom @ 2D material nanoplatforms. Adv Sci. 2019; 6 (21): 1901787.

[130] He Y, Liu S, Priest C, Shi Q, Wu G. Atomically dispersed metal-nitrogen-carbon catalysts for fuel cells: advances in catalyst design, electrode performance, and durability improvement. Chem Soc Rev. 2020; 49 (11): 3484- 3524.

[131] Cui X, Li W, Ryabchuk P, Junge K, Beller M. Bridging homogeneous and heterogeneous catalysis by heterogeneous single-metal-site catalysts. Nat Catal. 2018; 1 (6): 385- 397.

[132] Han B, Guo Y, Huang Y, et al. Strong metal-support interactions between Pt single atoms and TiO₂. Angew Chem Int Ed. 2020; 59 (29): 11824- 11829.

[133] Lang R, Du X, Huang Y, et al. Single-atom catalysts based on the metal-oxide interaction. Chem Rev. 2020; 120 (21): 11986- 12043.

[134] Lin J, Wang A, Qiao B, et al. Remarkable performance of Ir₁/FeO_x single-atom catalyst in water gas shift reaction. J Am Chem Soc. 2013; 135 (41): 15314- 15317.

[135] Wang A, Li J, Zhang T. Heterogeneous single-atom catalysis. Nat Rev Chem. 2018; 2 (6): 65- 81.

[136] Yang J, Chen B, Liu X, et al. Efficient and robust hydrogen evolution: phosphorus nitride imide nanotubes as supports for anchoring single ruthenium sites. Angew Chem. 2018; 130 (30): 9639- 9644.

[137] Cheng N, Zhang L, Doyle-Davis K, Sun X. Single-atom catalysts: from design to application. Electrochem Energy Rev. 2019; 2 (4): 539- 573.

[138] Liu H, Cheng M, Liu Y, et al. Modified UiO-66 as photocatalysts for boosting the carbon neutral energy cycle and solving environmental remediation issues. Coord Chem Rev. 2022; 458: 214428.

[139] Yang Q, Xu Q, Jiang HL. Metal-organic frameworks meet metal nanoparticles: synergistic effect for enhanced catalysis. Chem Soc Rev. 2017; 46 (15): 4774- 4808.

[140] Liang Z, Qu C, Xia D, Zou R, Xu Q. Atomically dispersed metal sites in MOF-based materials for electrocatalytic and photocatalytic energy conversion. Angew Chem Int Ed. 2018; 57 (31): 9604- 9633.

[141] Ma D-D, Zhu Q-L. MOF-based atomically dispersed metal catalysts: recent progress towards novel atomic configurations and electrocatalytic applications. Coord Chem Rev. 2020; 422: 213483.

[142] Zhang Y, Zhao J, Wang H, et al. Author correction: singleatom Cu anchored catalysts for photocatalytic renewable H₂ production with a quantum efficiency of 56%. Nat Commun. 2022; 13: 2062.

[143] Li Y, Wang S, Wang X, et al. Facile top-down strategy for direct metal atomization and coordination achieving a high turnover number in CO₂ photoreduction. J Am Chem Soc. 2020; 142 (45): 19259- 19267.

[144] Liang Z, Zhao R, Qiu T, Zou R, Xu Q. Metal-organic framework-derived materials for electrochemical energy applications. EnergyChem. 2019; 1 (1): 100001.

[145] Hou CC, Zou L, Sun L, et al. Single-atom iron catalysts on overhang-eave carbon cages for high performance oxygen reduction reaction. Angew Chem. 2020; 132 (19): 7454- 7459.

[146] Hou CC, Zou L, Xu Q. A hydrangea-like superstructure of open carbon cages with hierarchical porosity and highly active metal sites. Adv Mater. 2019; 31 (46): 1904689.

[147] Hou CC, Xu Q. Metal-organic frameworks for energy. Adv Energy Mater. 2019; 9 (23): 1801307.

[148] Trasatti S. Work function, electronegativity, and electrochemical behaviour of metals. J Electroanal Chem Interfacial Electrochem. 1972; 39 (1): 163- 184.

[149] Conway BE, Jerkiewicz G. Relation of energies and coverages of underpotential and overpotential deposited H at Pt and other metals to the ‘volcano curve’ for cathodic H₂ evolution kinetics. Electrochim Acta. 2000; 45 (25-26): 4075- 4083.

[150] Conway BE, Tilak BV. Interfacial processes involving electrocatalytic evolution and oxidation of H₂, and the role of chemisorbed H. Electrochim Acta. 2002; 47 (2223): 3571- 3594.

[151] Greeley J, Jaramillo TF, Bonde J, Chorkendorff I, Nørskov JK. Computational high throughput screening of electrocatalytic materials for hydrogen evolution. Nat Mater. 2006; 5 (11): 909- 913.

[152] Wang Y, Mehmood A, Zhao Y, Qu J, Luo Y. Computational studies on the selective polymerization of lactide catalyzed by bifunctional yttrium NHC catalyst. Inorganics. 2017; 5 (3): 46.

[153] Ye S, Luo F, Zhang Q, et al. Highly stable single Pt atomic sites anchored on aniline stacked graphene for hydrogen evolution reaction. Energy Environ Sci. 2019; 12 (3): 1000- 1007.

[154] Zhang H, An P, Zhou W, et al. Dynamic traction of latticeconfined platinum atoms into mesoporous carbon matrix for hydrogen evolution reaction. Sci Adv. 2018; 4 (1): eaao6657.

[155] Wei YS, Sun L, Wang M, et al. Fabricating dual-atom iron catalysts for efficient oxygen evolution reaction: a heteroatom modulator approach. Angew Chem Int Ed. 2020; 59 (37): 16013- 16022.

[156] Song Z, Zhu YN, Liu H, et al. Engineering the low coordinated Pt single atom to achieve the superior electrocatalytic performance toward oxygen reduction. Small. 2020; 16 (43): 2003096.

[157] Zhang H, Hwang S, Wang M, et al. Single atomic iron catalysts for oxygen reduction in acidic media: particle size control and thermal activation. J Am Chem Soc. 2017; 139 (40): 14143- 14149.

[158] Ling C, Shi L, Ouyang Y, Zeng XC, Wang J. Nanosheet supported single-metal atom bifunctional catalyst for overall water splitting. Nano Lett. 2017; 17 (8): 5133- 5139.

[159] Aijaz A, Karkamkar A, Choi YJ, et al. Immobilizing highly catalytically active Pt nanoparticles inside the pores of metal-organic framework: a double solvents approach. J Am Chem Soc. 2012; 134 (34): 13926- 13929.

[160] Chen X, Ma D-D, Chen B, et al. Metal-organic frameworkderived mesoporous carbon nanoframes embedded with atomically dispersed Fe-N active sites for efficient bifunctional oxygen and carbon dioxide electroreduction. Appl Catal B. 2020; 267: 118720.

[161] Jiang K, Siahrostami S, Akey AJ, et al. Transition-metal single atoms in a graphene shell as active centers for highly efficient artificial photosynthesis. Chem. 2017; 3 (6): 950- 960.

[162] Jiang K, Siahrostami S, Zheng T, et al. Isolated Ni single atoms in graphene nanosheets for high-performance CO₂ reduction. Energy Environ Sci. 2018; 11 (4): 893- 903.

[163] Jiao L, Wang Y, Jiang HL, Xu Q. Metal-organic frameworks as platforms for catalytic applications. Adv Mater. 2018; 30 (37): 1703663.

[164] Yan C, Ye Y, Lin L, et al. Improving CO₂ electroreduction over ZIF-derived carbon doped with Fe-N sites by an additional ammonia treatment. Catal Today. 2019; 330 (11): 252- 258.

[165] Chen GF, Ren S, Zhang L, et al. Advances in electrocatalytic N₂ reduction-strategies to tackle the selectivity challenge. Small Methods. 2019; 3 (6): 1800337.

[166] Foster SL, Bakovic SIP, Duda RD, et al. Catalysts for nitrogen reduction to ammonia. Nat Catal. 2018; 1 (7): 490- 500.

[167] Suryanto BHR, Du H-L, Wang D, Chen J, Simonov AN, MacFarlane DR. Challenges and prospects in the catalysis of electroreduction of nitrogen to ammonia. Nat Catal. 2019; 2 (4): 290- 296.

[168] Yan Z, Ji M, Xia J, Zhu H. Recent advanced materials for electrochemical and photoelectrochemical synthesis of ammonia from dinitrogen: one step closer to a sustainable energy future. Adv Energy Mater. 2020; 10 (11): 1902020.

[169] Geng Z, Liu Y, Kong X, et al. Achieving a record-high yield rate of 120.9 μgNH₃ mg^-1_cat.h^-1 for N₂ electrochemical reduction over Ru single-atom catalysts. Adv Mater. 2018; 30 (40): 1803498.

[170] Tang C, Qiao S-Z. How to explore ambient electrocatalytic nitrogen reduction reliably and insightfully. Chem Soc Rev. 2019; 48 (12): 3166- 3180.

[171] Shi L, Yin Y, Wang S, et al. Rigorous and reliable operations for electrocatalytic nitrogen reduction. Appl Catal B. 2020; 278 (19): 119325.

[172] Kakac S, Pramuanjaroenkij A, Zhou X. A review of numerical modeling of solid oxide fuel cells. Int J Hydrogen Energy. 2007; 32 (7): 761- 786.

[173] An L, Zhao TS, Shen SY, Wu QX, Chen R. Alkaline direct oxidation fuel cell with non platinum catalysts capable of converting glucose to electricity at high power output. J Power Sources. 2011; 196 (1): 186- 190.

[174] Tong Y, Yan X, Liang J, Dou SX. Metal-based electrocatalysts for methanol electro oxidation: progress, opportunities, and challenges. Small. 2021; 17 (9): 1904126.

[175] Wang Y, Chu F, Zeng J, et al. Single atom catalysts for fuel cells and rechargeable batteries: principles, advances, and opportunities. ACS Nano. 2021; 15 (1): 210- 239.

[176] Chen K, Huang G, Ma JL, et al. The stabilization effect of CO₂ in lithium-oxygen/CO₂. Angew Chem Int Ed. 2020; 59 (38): 16661- 16667.

[177] Chen L, Gu Q, Zhou X, Lee S, Xia Y, Liu Z. New-concept batteries based on aqueous Li⁺/Na⁺ mixed-ion electrolytes. Sci Rep. 2013; 3 (1): 1946.

[178] Chen W, Jin Y, Zhao J, Liu N, Cui Y. Nickel-hydrogen batteries for large-scale energy storage. P Natl A Sci USA. 2018; 115 (46): 11694- 11699.

[179] Chen T, Zhang Z, Cheng B, et al. Self-templated formation of interlaced carbon nanotubes threaded hollow Co₃S₄ nanoboxes for high-rate and heat-resistant lithium-sulfur batteries. J Am Chem Soc. 2017; 139 (36): 12710- 12715.

[180] Liu S, Li J, Yan X, et al. Superhierarchical cobalt-embedded nitrogen-doped porous carbon nanosheets as two-in-one hosts for high-performance lithium-sulfur batteries. Adv Mater. 2018; 30 (12): 1706895.

[181] Li W, Wang D, Zhang Y, et al. Defect engineering for fuel-cell electrocatalysts. Adv Mater. 2020; 32 (19): 1907879.

[182] Sun Z, Sun Z. Hydrogen generation from methanol reforming for fuel cell applications: a review. J Cent South Univ. 2020; 27 (4): 1074- 1103.

[183] Nitta N, Wu F, Lee JT, Yushin G. Li-ion battery materials: present and future. Mater Today. 2015; 18 (5): 252- 264.

[184] Wu F, Yushin G. Conversion cathodes for rechargeable lithium and lithium-ion batteries. Energy Environ Sci. 2017; 10 (2): 435- 459.

[185] Yuan K, Lützenkirchen-Hecht D, Li L, 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 (5): 2404- 2412.

[186] Back S, Kulkarni AR, Siahrostami S. Single metal atoms anchored in two-dimensional materials: bifunctional catalysts for fuel cell applications. ChemCatChem. 2018; 10 (14): 3034- 3039.

[187] Cheng W-Z, Liang J-L, Yin H-B, Wang Y-J, Yan W-F, Zhang J-N. Bifunctional iron phtalocyanine metal-organic framework catalyst for ORR, OER and rechargeable zinc-air battery. Rare Met. 2020; 39 (7): 815- 823.

[188] Xiang Z, Cao D, Huang L, Shui J, Wang M, Dai L. Nitrogendoped holey graphitic carbon from 2D covalent organic polymers for oxygen reduction. Adv Mater. 2014; 26 (20): 3315- 3320.

[189] Yu H, Fisher A, Cheng D, Cao D. Cu, N-codoped hierarchical porous carbons as electrocatalysts for oxygen reduction reaction. ACS Appl Mater Interfaces. 2016; 8 (33): 21431- 21439.

[190] Hou CC, Zou L, Wang Y, Xu Q. MOF-mediated fabrication of a porous 3D superstructure of carbon nanosheets decorated with ultrafine cobalt phosphide nanoparticles for efficient electrocatalysis and zinc-air batteries. Angew Chem Int Ed. 2020; 59 (48): 21360- 21366.

[191] Kraytsberg A, Ein-Eli Y. Review on Li-air batteriesopportunities, limitations and perspective. J Power Sources. 2011; 196 (3): 886- 893.

[192] Zhang Y, Geng H, Wei W, Ma J, Chen L, Li CC. Challenges and recent progress in the design of advanced electrode materials for rechargeable mg batteries. Energy Storage Mater. 2019; 20 (5): 118- 138.

[193] Chen Z, Wang Q, Zhang X, et al. N-doped defective carbon with trace co for efficient rechargeable liquid electrolyte-/allsolid-state Zn-air batteries. Sci Bull. 2018; 63 (9): 548- 555.

[194] Cai W, Zhang X, Shi J, et al. Contribution of carbon support in cost-effective metal oxide/carbon composite catalysts for the alkaline oxygen evolution reaction. Catal Commun. 2019; 127 (10): 5- 9.

[195] Wu T, Pi M, Wang X, Zhang D, Chen S. Three-dimensional metal-organic framework derived porous CoP₃ concave polyhedrons as superior bifunctional electrocatalysts for the evolution of hydrogen and oxygen. Phys Chem Chem Phys. 2017; 19 (3): 2104- 2110.

[196] Chen Y, Gao R, Ji S, 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 (6): 3212- 3221.

[197] Han X-R, Guo X-T, XuM-J , Pang H, Ma Y-W. Clean utilization of palm kernel shell: sustainable and naturally heteroatomdoped porous activated carbon for lithium-sulfur batteries. Rare Met. 2020; 39 (9): 1099- 1106.

[198] Ma F, Wan Y, Wang X, et al. Bifunctional atomically dispersed Mo-N₂/C nanosheets boost lithium sulfide deposition/decomposition for stable lithium-sulfur batteries. ACS Nano. 2020; 14 (8): 10115- 10126.

[199] Yang Y, Zheng G, Cui Y. Nanostructured sulfur cathodes. Chem Soc Rev. 2013; 42 (7): 3018- 3032.

[200] Li Y, Zhou P, Li H, et al. A freestanding flexible single-atom cobalt-based multifunctional interlayer toward reversible and durable lithium-sulfur batteries. Small Methods. 2020; 4 (3): 1900701.

[201] Cheng F, Liang J, Tao Z, Chen J. Functional materials for rechargeable batteries. Adv Mater. 2011; 23 (15): 1695- 1715.

[202] Kim T-H, Park J-S, Chang SK, Choi S, Ryu JH, Song H-K. The current move of lithium ion batteries towards the next phase. Adv Energy Mater. 2012; 2 (7): 860- 872.

[203] Wang Y-X, Zhang B, Lai W, et al. Room-temperature sodium-sulfur batteries: a comprehensive review on research progress and cell chemistry. Adv Energy Mater. 2017; 7 (24): 1602829.

[204] Li T, Xu J, Wang C, Wu W, Su D, Wang G. The latest advances in the critical factors (positive electrode, electrolytes, separators) for sodium-sulfur battery. J Alloys Compd. 2019; 792: 797- 817.

[205] Zhang SS, Foster D, Read J. Discharge characteristic of a nonaqueous electrolyte Li/O₂ battery. J Power Sources. 2010; 195 (4): 1235- 1240.

[206] Lyu Z, Zhou Y, Dai W, et al. Recent advances in understanding of the mechanism and control of Li₂O₂ formation in aprotic Li-O₂ batteries. Chem Soc Rev. 2017; 46 (19): 6046- 6072.

[207] Sun B, Chen S, Liu H, Wang G. Mesoporous carbon nanocube architecture for high performance lithium-oxygen batteries. Adv Funct Mater. 2015; 25 (28): 4436- 4444.

[208] Wang P, Ren Y, Wang R, et al. Atomically dispersed cobalt catalyst anchored on nitrogen doped carbon nanosheets for lithium-oxygen batteries. Nat Commun. 2020; 11: 1576.

[209] Song L-N, Zhang W, Wang Y, et al. Tuning lithium-peroxide formation and decomposition routes with single-atom catalysts for lithium-oxygen batteries. Nat Commun. 2020; 11: 2191.

[210] Lin D, Liu Y, Cui Y. Reviving the lithium metal anode for high-energy batteries. Nat Nanotechnol. 2017; 12 (3): 194- 206.

[211] Zhang X, Wang A, Liu X, Luo J. Dendrites in lithium metal anodes: suppression, regulation, and elimination. Acc Chem Res. 2019; 52 (11): 3223- 3232.

[212] Zheng J, Kim MS, Tu Z, Choudhury S, Tang T, Archer LA. Regulating electrodeposition morphology of lithium: towards commercially relevant secondary Li metal batteries. Chem Soc Rev. 2020; 49 (9): 2701- 2750.

[213] Yang T, Qian T, Sun Y, Zhong J, Rosei F, Yan C. Mega high utilization of sodium metal anodes enabled by single zinc atom sites. Nano Lett. 2019; 19 (11): 7827- 7835.

RIGHTS & PERMISSIONS

2023 2023 The Authors. Carbon Energy published by Wenzhou University and John Wiley & Sons Australia, Ltd.