journal article·2022-12Open access

Catalysts for electrochemical ammonia oxidation: Trend, challenge, and promise

Sol A. Lee, Mi Gyoung Lee, Ho Won Jang

Science China Materials· Volume 65· Issue 12

Abstract

Developing sustainable and clean energy technology is critial to address the current energy and environmental crisis. As an energy carrier, hydrogen has been getting attention due to its abundance, high energy density, and zero carbon emission. Due to the difficulty of hydrogen storage and transport, the electro-oxidation of ammonia shows great potential for renewable energy since it satisfies both energy supply and environmental protection as a carbon-free fuel with high hydrogen content. However, ammonia electro-oxidation is a sluggish reaction and shows low durability. Understanding the complicated mechanism and intermediates is conducive to developing efficient electrocatalysts with high catalytic activity and durability. This review begins with the ammonia oxidation technologies and their principles. The two typical mechanisms for ammonia electro-oxidation, Oswin-Salomon mechanism and Gerischer-Mauerer mechanism, are discussed, and attention to the poisoning species is included. Then, the electrocatalysts for ammonia reaction are classified into Pt-based catalysts and non-noble metal-based catalysts, and their performances are reviewed with various strategies. Based on the progress on the electrochemical ammonia oxidation catalysts, the challenges and future insight on ammonia oxidation reaction are discussed and proposed.
Source: expertdata · Quality: candidate unverified · Source record ↗

Research context

OpenAlex topics: Ammonia Synthesis and Nitrogen Reduction · Advanced Photocatalysis Techniques · Catalytic Processes in Materials Science

SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.

References (100+)

Show source-provided references
1. Zhou B, Zhang N, Wu Y, et al. An option for green and sustainable future: Electrochemical conversion of ammonia into nitrogen. J Energy Chem, 2021, 60: 384–40210.1016/j.jechem.2021.01.011 ↗
2. Lee SA, Choi S, Kim C, et al. Si-based water oxidation photoanodes conjugated with earth-abundant transition metal-based catalysts. ACS Mater Lett, 2020, 2: 107–12610.1021/acsmaterialslett.9b00422 ↗
3. Gwak J, Choun M, Lee J. Alkaline ammonia electrolysis on electro-deposited platinum for controllable hydrogen production. Chem SusChem, 2016, 9: 403–408
4. Lan R, Tao S. Direct ammonia alkaline anion-exchange membrane fuel cells. Electrochem Solid-State Lett, 2010, 13: B8310.1149/1.3428469 ↗
5. Iulianelli A, Liguori S, Wilcox J, et al. Advances on methane steam reforming to produce hydrogen through membrane reactors technology: A review. Catal Rev, 2016, 58: 1–3510.1080/01614940.2015.1099882 ↗
6. de Wild P. Catalytic production of hydrogen from methanol. Catal Today, 2000, 60: 3–1010.1016/S0920-5861(00)00311-4 ↗
7. Zhong C, Hu WB, Cheng YF. Recent advances in electrocatalysts for electro-oxidation of ammonia. J Mater Chem A, 2013, 1: 3216–323810.1039/C2TA00607C ↗
8. Siddharth K, Chan Y, Wang L, et al. Ammonia electro-oxidation reaction: Recent development in mechanistic understanding and electrocatalyst design. Curr Opin Electrochem, 2018, 9: 151–15710.1016/j.coelec.2018.03.011 ↗
9. Dong BX, Ichikawa T, Hanada N, et al. Liquid ammonia electrolysis by platinum electrodes. J Alloys Compd, 2011, 509: S891–S89410.1016/j.jallcom.2010.10.157 ↗
10. Little DJ, Edwards DO, Smith III MR, et al. As precious as platinum: Iron nitride for electrocatalytic oxidation of liquid ammonia. ACS Appl Mater Interfaces, 2017, 9: 16228–1623510.1021/acsami.7b02639 ↗
11. Schüth F, Palkovits R, Schlögl R, et al. Ammonia as a possible element in an energy infrastructure: Catalysts for ammonia decomposition. Energy Environ Sci, 2012, 5: 6278–628910.1039/C2EE02865D ↗
12. Yang Y, Kim J, Jo H, et al. A rigorous electrochemical ammonia electrolysis protocol with in operando quantitative analysis. J Mater Chem A, 2021, 9: 11571–1157910.1039/D1TA00363A ↗
13. Sun HY, Xu GR, Li FM, et al. Hydrogen generation from ammonia electrolysis on bifunctional platinum nanocubes electrocatalysts. J Energy Chem, 2020, 47: 234–24010.1016/j.jechem.2020.01.035 ↗
14. Li Y, Li X, Pillai HS, et al. Ternary PtIrNi catalysts for efficient electrochemical ammonia oxidation. ACS Catal, 2020, 10: 3945–395710.1021/acscatal.9b04670 ↗
15. Pourrahimi AM, Andersson RL, Tjus K, et al. Making an ultralow platinum content bimetallic catalyst on carbon fibres for electro-oxidation of ammonia in wastewater. Sustain Energy Fuels, 2019, 3: 2111–212410.1039/C9SE00161A ↗
16. Xi X, Fan Y, Zhang K, et al. Carbon-free sustainable energy technology: Electrocatalytic ammonia oxidation reaction. Chem Eng J, 2022, 435: 13481810.1016/j.cej.2022.134818 ↗
17. Lan R, Tao S. Ammonia as a suitable fuel for fuel cells. Front Energy Res, 2014, 2: 3510.3389/fenrg.2014.00035 ↗
18. Adli NM, Zhang H, Mukherjee S, et al. Review—Ammonia oxidation electrocatalysis for hydrogen generation and fuel cells. J Electrochem Soc, 2018, 165: J3130–J314710.1149/2.0191815jes ↗
19. Zhao Y, Wang T, Setzler BP, et al. A high-performance gas-fed direct ammonia hydroxide exchange membrane fuel cell. ACS Energy Lett, 2021, 6: 1996–200210.1021/acsenergylett.1c00370 ↗
20. Li Y, Pillai HS, Wang T, et al. High-performance ammonia oxidation catalysts for anion-exchange membrane direct ammonia fuel cells. Energy Environ Sci, 2021, 14: 1449–146010.1039/D0EE03351K ↗
21. Zhao Y, Setzler BP, Wang J, et al. An efficient direct ammonia fuel cell for affordable carbon-neutral transportation. Joule, 2019, 3: 2472–248410.1016/j.joule.2019.07.005 ↗
22. Little DJ, Smith, III MR, Hamann TW. Electrolysis of liquid ammonia for hydrogen generation. Energy Environ Sci, 2015, 8: 2775–278110.1039/C5EE01840D ↗
23. Goshome K, Yamada T, Miyaoka H, et al. High compressed hydrogen production via direct electrolysis of liquid ammonia. Int J Hydrogen Energy, 2016, 41: 14529–1453410.1016/j.ijhydene.2016.06.137 ↗
24. Dong BX, Tian H, Wu YC, et al. Improved electrolysis of liquid ammonia for hydrogen generation via ammonium salt electrolyte and Pt/Rh/Ir electrocatalysts. Int J Hydrogen Energy, 2016, 41: 14507–1451810.1016/j.ijhydene.2016.06.212 ↗
25. Oswin HG, Salomon M. The anodic oxidation of ammonia at platinum black electrodes in aqueous KOH electrolyte. Can J Chem, 1963, 41: 1686–169410.1139/v63-243 ↗
26. Gerischer H, Mauerer A. Untersuchungen zur anodischen oxidation von ammoniak an platin-elektroden. J Electroanal Chem Interfacial Electrochem, 1970, 25: 421–43310.1016/S0022-0728(70)80103-6 ↗
27. Elnabawy AO, Herron JA, Karraker S, et al. Structure sensitivity of ammonia electro-oxidation on transition metal surfaces: A first-principles study. J Catal, 2021, 397: 137–14710.1016/j.jcat.2021.03.010 ↗
28. Katsounaros I, Chen T, Gewirth AA, et al. Evidence for decoupled electron and proton transfer in the electrochemical oxidation of ammonia on Pt(100). J Phys Chem Lett, 2016, 7: 387–39210.1021/acs.jpclett.5b02556 ↗
29. de Vooys ACA, Koper MTM, van Santen RA, et al. The role of adsorbates in the electrochemical oxidation of ammonia on noble and transition metal electrodes. J Electroanal Chem, 2001, 506: 127–13710.1016/S0022-0728(01)00491-0 ↗
30. Diaz LA, Valenzuela-Muñiz A, Muthuvel M, et al. Analysis of ammonia electro-oxidation kinetics using a rotating disk electrode. Electrochim Acta, 2013, 89: 413–42110.1016/j.electacta.2012.11.064 ↗
31. Gootzen JFE, Wonders AH, Visscher W, et al. A DEMS and cyclic voltammetry study of NH3 oxidation on platinized platinum. Electrochim Acta, 1998, 43: 1851–186110.1016/S0013-4686(97)00285-5 ↗
32. Finkelstein DA, Bertin E, Garbarino S, et al. Mechanistic similarity in catalytic N2 production from NH3 and NO2− at Pt(100) thin films: Toward a universal catalytic pathway for simple N-containing species, and its application to in situ removal of NH3 poisons. J Phys Chem C, 2015, 119: 9860–987810.1021/acs.jpcc.5b00949 ↗
33. Kim H, Yang W, Lee WH, et al. Operando stability of platinum electrocatalysts in ammonia oxidation reactions. ACS Catal, 2020, 10: 11674–1168410.1021/acscatal.0c02413 ↗
34. Wasmus S, Vasini EJ, Krausa M, et al. DEMS-cyclic voltammetry investigation of the electrochemistry of nitrogen compounds in 0.5 mol L−1 potassium hydroxide. Electrochim Acta, 1994, 39: 23–3110.1016/0013-4686(94)85006-2 ↗
35. Kim H, Chung MW, Choi CH. NOx-induced deactivation of Pt electrocatalysis towards the ammonia oxidation reaction. Electrochem Commun, 2018, 94: 31–3510.1016/j.elecom.2018.08.001 ↗
36. Moran E, Cattaneo C, Mishima H, et al. Ammonia oxidation on electrodeposited Pt-Ir alloys. J Solid State Electrochem, 2008, 12: 583–58910.1007/s10008-007-0407-0 ↗
37. Peng W, Xiao L, Huang B, et al. Inhibition effect of surface oxygenated species on ammonia oxidation reaction. J Phys Chem C, 2011, 115: 23050–2305610.1021/jp2081148 ↗
38. de Vooys ACA, Mrozek MF, Koper MTM, et al. The nature of chemisorbates formed from ammonia on gold and palladium electrodes as discerned from surface-enhanced Raman spectroscopy. Electrochem Commun, 2001, 3: 293–29810.1016/S1388-2481(01)00156-4 ↗
39. Vidal-Iglesias FJ, Solla-Gullón J, Pérez JM, et al. Evidence by SERS of azide anion participation in ammonia electrooxidation in alkaline medium on nanostructured Pt electrodes. Electrochem Commun, 2006, 8: 102–10610.1016/j.elecom.2005.11.002 ↗
40. Wei RL, Liu Y, Chen Z, et al. Ammonia oxidation on iridium electrode in alkaline media: An in situ ATR-SEIRAS study. J Electroanal Chem, 2021, 896: 11525410.1016/j.jelechem.2021.115254 ↗
41. Katayama Y, Okanishi T, Muroyama H, et al. Enhanced supply of hydroxyl species in CeO2-modified platinum catalyst studied by in situ ATR-FTIR spectroscopy. ACS Catal, 2016, 6: 2026–203410.1021/acscatal.6b00108 ↗
42. Matsui T, Suzuki S, Katayama Y, et al. In situ attenuated total reflection infrared spectroscopy on electrochemical ammonia oxidation over Pt electrode in alkaline aqueous solutions. Langmuir, 2015, 31: 11717–1172310.1021/acs.langmuir.5b02330 ↗
43. Siddharth K, Alam P, Hossain MD, et al. Hydrazine detection during ammonia electro-oxidation using an aggregation-induced emission dye. J Am Chem Soc, 2021, 143: 2433–244010.1021/jacs.0c13178 ↗
44. Vidal-Iglesias FJ, Solla-Gullón J, Feliu JM, et al. DEMS study of ammonia oxidation on platinum basal planes. J Electroanal Chem, 2006, 588: 331–33810.1016/j.jelechem.2006.01.009 ↗
45. Bunce NJ, Bejan D. Mechanism of electrochemical oxidation of ammonia. Electrochim Acta, 2011, 56: 8085–809310.1016/j.electacta.2011.07.078 ↗
46. Medford AJ, Vojvodic A, Hummelshøj JS, et al. From the Sabatier principle to a predictive theory of transition-metal heterogeneous catalysis. J Catal, 2015, 328: 36–4210.1016/j.jcat.2014.12.033 ↗
47. Zhu C, Lan B, Wei RL, et al. Potential-dependent selectivity of ethanol complete oxidation on Rh electrode in alkaline media: A synergistic study of electrochemical ATR-SEIRAS and IRAS. ACS Catal, 2019, 9: 4046–405310.1021/acscatal.9b00138 ↗
48. Yang YY, Ren J, Li QX, et al. Electrocatalysis of ethanol on a Pd electrode in alkaline media: An in situ attenuated total reflection surface-enhanced infrared absorption spectroscopy study. ACS Catal, 2014, 4: 798–80310.1021/cs401198t ↗
49. Silva JCM, Assumpção MHMT, Hammer P, et al. Iridium-rhodium nanoparticles for ammonia oxidation: Electrochemical and fuel cell studies. ChemElectroChem, 2017, 4: 1101–110710.1002/celc.201600701 ↗
50. Zhou L, Cheng Y. Catalytic electrolysis of ammonia on platinum in alkaline solution for hydrogen generation. Int J Hydrogen Energy, 2008, 33: 5897–590410.1016/j.ijhydene.2008.08.009 ↗
51. Skachkov D, Venkateswara Rao C, Ishikawa Y. Combined first-principles molecular dynamics/density functional theory study of ammonia electrooxidation on Pt(100) electrode. J Phys Chem C, 2013, 117: 25451–2546610.1021/jp4048874 ↗
52. Galipaud J, Roy C, Martin MH, et al. Electrooxidation of ammonia at tuned (100)Pt surfaces by using epitaxial thin films. ChemElectroChem, 2015, 2: 1187–119810.1002/celc.201500045 ↗
53. Siddharth K, Hong Y, Qin X, et al. Surface engineering in improving activity of Pt nanocubes for ammonia electrooxidation reaction. Appl Catal B-Environ, 2020, 269: 11882110.1016/j.apcatb.2020.118821 ↗
54. Li ZF, Wang Y, Botte GG. Revisiting the electrochemical oxidation of ammonia on carbon-supported metal nanoparticle catalysts. Electrochim Acta, 2017, 228: 351–36010.1016/j.electacta.2017.01.020 ↗
55. Ye JY, Lin JL, Zhou ZY, et al. Ammonia electrooxidation on dendritic Pt nanostructures in alkaline solutions investigated by in-situ FTIR spectroscopy and online electrochemical mass spectroscopy. J Electroanal Chem, 2018, 819: 495–50110.1016/j.jelechem.2017.12.062 ↗
56. Lin X, Zhang X, Wang Z, et al. Hyperbranched concave octahedron of PtIrCu nanocrystals with high-index facets for efficiently electrochemical ammonia oxidation reaction. J Colloid Interface Sci, 2021, 601: 1–1110.1016/j.jcis.2021.04.068 ↗
57. Choi S, Lee SA, Yang H, et al. Stabilization of NiFe layered double hydroxides on n-Si by an activated TiO2 interlayer for efficient solar water oxidation. ACS Appl Energy Mater, 2020, 3: 12298–1230710.1021/acsaem.0c02355 ↗
58. Clark EL, Hahn C, Jaramillo TF, et al. Electrochemical CO2 reduction over compressively strained CuAg surface alloys with enhanced multicarbon oxygenate selectivity. J Am Chem Soc, 2017, 139: 15848–1585710.1021/jacs.7b08607 ↗
59. Liang C, Zou P, Nairan A, et al. Exceptional performance of hierarchical Ni−Fe oxyhydroxide@NiFe alloy nanowire array electrocatalysts for large current density water splitting. Energy Environ Sci, 2020, 13: 86–9510.1039/C9EE02388G ↗
60. Endo K, Katayama Y, Miura T. Pt-Ir and Pt-Cu binary alloys as the electrocatalyst for ammonia oxidation. Electrochim Acta, 2004, 49: 1635–163810.1016/S0013-4686(03)00993-9 ↗
61. Lomocso TL, Baranova EA. Electrochemical oxidation of ammonia on carbon-supported bi-metallic PtM (M = Ir, Pd, SnOx) nanoparticles. Electrochim Acta, 2011, 56: 8551–855810.1016/j.electacta.2011.07.041 ↗
62. Wang J, Heo J, Chen C, et al. Ammonia oxidation enhanced by photopotential generated by plasmonic excitation of a bimetallic electrocatalyst. Angew Chem Int Ed, 2020, 59: 18430–1843410.1002/anie.202007202 ↗
63. Chan YT, Siddharth K, Shao M. Investigation of cubic Pt alloys for ammonia oxidation reaction. Nano Res, 2020, 13: 1920–192710.1007/s12274-020-2712-1 ↗
64. Zhu J, Zheng X, Wang J, et al. Structurally ordered Pt-Zn/C series nanoparticles as efficient anode catalysts for formic acid electrooxidation. J Mater Chem A, 2015, 3: 22129–2213510.1039/C5TA05699C ↗
65. Jiang J. Promotion of PtIr and Pt catalytic activity towards ammonia electrooxidation through the modification of Zn. Electrochem Commun, 2017, 75: 52–5510.1016/j.elecom.2016.12.017 ↗
66. Katayama Y, Okanishi T, Muroyama H, et al. Electrochemical oxidation of ammonia over rare earth oxide modified platinum catalysts. J Phys Chem C, 2015, 119: 9134–914110.1021/acs.jpcc.5b01710 ↗
67. Liu J, Chen B, Kou Y, et al. Pt-decorated highly porous flower-like Ni particles with high mass activity for ammonia electro-oxidation. J Mater Chem A, 2016, 4: 11060–1106810.1039/C6TA02284G ↗
68. Morita S, Kudo E, Shirasaka R, et al. Electrochemical oxidation of ammonia by multi-wall-carbon-nanotube-supported Pt shell-Ir core nanoparticles synthesized by an improved Cu short circuit deposition method. J Electroanal Chem, 2016, 762: 29–3610.1016/j.jelechem.2015.12.017 ↗
69. Endo K, Nakamura K, Katayama Y, et al. Pt-Me (Me = Ir, Ru, Ni) binary alloys as an ammonia oxidation anode. Electrochim Acta, 2004, 49: 2503–250910.1016/j.electacta.2004.01.025 ↗
70. Kang Y, Wang W, Li J, et al. High performance PtxEu alloys as effective electrocatalysts for ammonia electro-oxidation. Int J Hydrogen Energy, 2017, 42: 18959–1896710.1016/j.ijhydene.2017.05.216 ↗
71. Zhou Y, Zhang G, Yu M, et al. High mass and specific activity for ammonia electro-oxidation through optimization of dispersion degree and particle size of Pt-Ir nanoparticles over N-doped reductive graphene oxide. ChemistrySelect, 2018, 3: 3433–344310.1002/slct.201800168 ↗
72. Manso R, Song L, Liang Z, et al. CuPt and CuPtRu nanostructures for ammonia oxidation reaction. ECS Trans, 2018, 85: 177–18210.1149/08512.0177ecst ↗
73. Wang L, Zhu Y, Wen Y, et al. Regulating the local charge distribution of Ni active sites for the urea oxidation reaction. Angew Chem Int Ed, 2021, 60: 10577–1058210.1002/anie.202100610 ↗
74. Lan R, Irvine JTS, Tao S. Ammonia and related chemicals as potential indirect hydrogen storage materials. Int J Hydrogen Energy, 2012, 37: 1482–149410.1016/j.ijhydene.2011.10.004 ↗
75. Shih YJ, Huang YH, Huang CP. Electrocatalytic ammonia oxidation over a nickel foam electrode: Role of Ni(OH)2(s)−NiOOH(s) nanocatalysts. Electrochim Acta, 2018, 263: 261–27110.1016/j.electacta.2018.01.045 ↗
76. Shih YJ, Huang YH, Huang CP. In-situ electrochemical formation of nickel oxyhydroxide (NiOOH) on metallic nickel foam electrode for the direct oxidation of ammonia in aqueous solution. Electrochim Acta, 2018, 281: 410–41910.1016/j.electacta.2018.05.169 ↗
77. Kapałka A, Cally A, Neodo S, et al. Electrochemical behavior of ammonia at Ni/Ni(OH)2 electrode. Electrochem Commun, 2010, 12: 18–2110.1016/j.elecom.2009.10.026 ↗
78. Yao K, Cheng YF. Electrodeposited Ni−Pt binary alloys as electrocatalysts for oxidation of ammonia. J Power Sources, 2007, 173: 96–10110.1016/j.jpowsour.2007.04.081 ↗
79. Yao K, Cheng YF. Investigation of the electrocatalytic activity of nickel for ammonia oxidation. Mater Chem Phys, 2008, 108: 247–25010.1016/j.matchemphys.2007.09.030 ↗
80. Despić AR, Dražić DM, Rakin PM. Kinetics of electrochemical oxidation of ammonia in alkaline solution. Electrochim Acta, 1966, 11: 997–100510.1016/0013-4686(66)80038-5 ↗
81. Zöllig H, Morgenroth E, Udert KM. Inhibition of direct electrolytic ammonia oxidation due to a change in local pH. Electrochim Acta, 2015, 165: 348–35510.1016/j.electacta.2015.02.162 ↗
82. Lee CG. Effect of temperature on the cathodic overpotential in a molten carbonate fuel cell. J Electroanal Chem, 2013, 701: 36–4210.1016/j.jelechem.2013.04.025 ↗
83. Wei C, Sun Y, Scherer GG, et al. Surface composition dependent ligand effect in tuning the activity of nickel-copper bimetallic electrocatalysts toward hydrogen evolution in alkaline. J Am Chem Soc, 2020, 142: 7765–777510.1021/jacs.9b12005 ↗
84. Jabłońska M, Beale AM, Nocuń M, et al. Ag−Cu based catalysts for the selective ammonia oxidation into nitrogen and water vapour. Appl Catal B-Environ, 2018, 232: 275–28710.1016/j.apcatb.2018.03.029 ↗
85. Sonia Theres G, Velayutham G, Santhana Krishnan P, et al. Synergistic impact of Ni−Cu hybrid oxides deposited on ordered mesoporous carbon scaffolds as non-noble catalyst for methanol oxidation. J Mater Sci, 2019, 54: 1502–151910.1007/s10853-018-2884-1 ↗
86. Xie J, Gao L, Cao S, et al. Copper-incorporated hierarchical wire-on-sheet α-Ni(OH)2 nanoarrays as robust trifunctional catalysts for synergistic hydrogen generation and urea oxidation. J Mater Chem A, 2019, 7: 13577–1358410.1039/C9TA02891A ↗
87. Xu M, Wei M. Layered double hydroxide-based catalysts: Recent advances in preparation, structure, and applications. Adv Funct Mater, 2018, 28: 180294310.1002/adfm.201802943 ↗
88. Yang A, Wang J, Su K, et al. Modulating hydroxyl-rich interfaces on nickel-copper double hydroxide nanotyres to pre-activate alkaline ammonia oxidation reactivity. Chem Eur J, 2021, 27: 4869–487510.1002/chem.202004904 ↗
89. Xu W, Lan R, Du D, et al. Directly growing hierarchical nickel-copper hydroxide nanowires on carbon fibre cloth for efficient electrooxidation of ammonia. Appl Catal B-Environ, 2017, 218: 470–47910.1016/j.apcatb.2017.07.005 ↗
90. Xu W, Du D, Lan R, et al. Electrodeposited NiCu bimetal on carbon paper as stable non-noble anode for efficient electrooxidation of ammonia. Appl Catal B-Environ, 2018, 237: 1101–110910.1016/j.apcatb.2016.11.003 ↗
91. Jiang X, Ying D, Liu X, et al. Identification of the role of Cu site in Ni−Cu hydroxide for robust and high selective electrochemical ammonia oxidation to nitrite. Electrochim Acta, 2020, 345: 13615710.1016/j.electacta.2020.136157 ↗
92. Nagita K, Yuhara Y, Fujii K, et al. Ni- and Cu-co-intercalated layered manganese oxide for highly efficient electro-oxidation of ammonia selective to nitrogen. ACS Appl Mater Interfaces, 2021, 13: 28098–2810710.1021/acsami.1c04422 ↗
93. Tsai MH, Chen TC, Juang Y, et al. High catalytic performance of CuCo/nickel foam electrode for ammonia electrooxidation. Electrochem Commun, 2020, 121: 10687510.1016/j.elecom.2020.106875 ↗
94. Shih YJ, Hsu CH. Kinetics and highly selective N2 conversion of direct electrochemical ammonia oxidation in an undivided cell using NiCo oxide nanoparticle as the anode and metallic Cu/Ni foam as the cathode. Chem Eng J, 2021, 409: 12802410.1016/j.cej.2020.128024 ↗
95. Wang R, Liu H, Zhang K, et al. Ni(II)/Ni(III) redox couple endows Ni foam-supported Ni2P with excellent capability for direct ammonia oxidation. Chem Eng J, 2021, 404: 12679510.1016/j.cej.2020.126795 ↗
96. He S, Chen Y, Wang M, et al. Metal nitride nanosheets enable highly efficient electrochemical oxidation of ammonia. Nano Energy, 2021, 80: 10552810.1016/j.nanoen.2020.105528 ↗
97. Gieshoff T, Kehl A, Schollmeyer D, et al. Insights into the mechanism of anodic N−N bond formation by dehydrogenative coupling. J Am Chem Soc, 2017, 139: 12317–1232410.1021/jacs.7b07488 ↗
98. Schiffer ZJ, Lazouski N, Corbin N, et al. Nature of the first electron transfer in electrochemical ammonia activation in a nonaqueous medium. J Phys Chem C, 2019, 123: 9713–972010.1021/acs.jpcc.9b00669 ↗
99. Nørskov JK, Abild-Pedersen F, Studt F, et al. Density functional theory in surface chemistry and catalysis. Proc Natl Acad Sci USA, 2011, 108: 937–94310.1073/pnas.1006652108 ↗
100. He S, Somayaji V, Wang M, et al. High entropy spinel oxide for efficient electrochemical oxidation of ammonia. Nano Res, 2022, 15: 4785–479110.1007/s12274-021-3665-8 ↗