Two-in-One Integrated CO₂/N₂ Conversion and Related Systems: Potential, Status, and Future

Abstract

Electro-conversion of CO₂, N₂, or NO_x into valuable chemicals, e.g., CO, HCOOH, and NH₃, has become a favorite for mitigating environmental pollution and addressing the energy crisis. Typical electrolysis systems, which pair a cathodic CO₂, N₂, or NO_x reduction reaction (CO₂RR, NRR, or NO_xRR) with an anodic oxygen evolution reaction (OER), hinder the economic viability and efficiency of the overall system due to the energy-intensive OER process. Innovative “Two-in-One” systems that integrate CO₂RR, NRR, or NO_xRR with a value-added oxidation process or energy storage unit, rather than OER, within a single device have emerged as promising alternatives. However, these “Two-in-One” integrated systems still face numerous pressing challenges in advancing the industrialization of CO₂-, N₂-, and NO_x-related conversion technologies, such as limited application scenarios, low efficiency, and restricted products. Herein, we discuss the technological breakthroughs of “Two-in-One” systems from the perspective of value-added chemical co-production, environmental remediation, and energy storage, aiming to provide readers with fresh research viewpoints to improve efficiency, increase product variety and selectivity, maximize product value, and reduce costs. Specifically, the design principles of “Two-in-One” systems, specific design strategies for dual-value-added chemical co-production, environmental pollutant recycling, and energy storage applications, along with techno-economic and environmental impacts, are discussed in detail. Finally, key research opportunities and challenges are highlighted to facilitate further developments.

Graphical Abstract

From the perspectives of value-added chemical synthesis, environmental remediation, and energy storage, we discuss innovative “Two-in-One” systems that integrate CO₂, N₂, or NO_x reduction reactions with a value-added oxidation process or energy storage unit, rather than oxygen evolution reaction (OER), within a single device, as promising alternatives for solving the problem of high energy consumption and meeting real-world sustainability needs.

Keywords

Integrated dual-function systems / CO₂RR / NRR/NO_xRR / Alternative oxidation / Chemical synthesis / Environmental remediation / Metal-CO₂/metal-N₂ batteries

References

[1] Hong P, Xu CF, Yan CZ, et al. . Prussian blue and its analogues for commercializing fast-charging sodium/potassium-ion batteries. ACS Energy Lett., 2025, 10: 750-778.

[2] Zhang QM, Wang YZ, Deng Q, et al. . In situ and real-time monitoring the chemical and thermal evolution of lithium-ion batteries with single-crystalline Ni-rich layered oxide cathode. Angew. Chem.-Int. Edit., 2024, 63e202401716

[3] Dong YL, Xu CF, Li YL, et al. . Ultrahigh-rate and ultralong-duration sodium storage enabled by sodiation-driven reconfiguration. Adv. Energy Mater., 2023, 132204324

[4] De Luna P, Hahn C, Higgins D, et al. . What would it take for renewably powered electrosynthesis to displace petrochemical processes?. Science, 2019, 364eaav3506

[5] Huang ZL, Rafiq M, Woldu AR, et al. . Recent progress in electrocatalytic nitrogen reduction to ammonia (NRR). Coord. Chem. Rev., 2023, 478214981

[6] Xu CF, Dong YL, Zhao HP, et al. . CO₂ conversion toward real-world applications: electrocatalysis versus CO₂ batteries. Adv. Funct. Mater., 2023, 332300926

[7] Li L, Li XD, Sun YF, et al. . Rational design of electrocatalytic carbon dioxide reduction for a zero-carbon network. Chem. Soc. Rev., 2022, 51: 1234-1252.

[8] Mushtaq MA, Arif M, Yasin G, et al. . Recent developments in heterogeneous electrocatalysts for ambient nitrogen reduction to ammonia: activity, challenges, and future perspectives. Renew. Sustain. Energy Rev., 2023, 176113197

[9] Xiong YC, Wang YH, Zhou JW, et al. . Electrochemical nitrate reduction: ammonia synthesis and the beyond. Adv. Mater., 2024, 362304021

[10] Wang N, Cao Z, Zheng XL, et al. . Hydration-effect-promoting Ni–Fe oxyhydroxide catalysts for neutral water oxidation. Adv. Mater., 2020, 321906806

[11] Zhang LS, Wang LP, Wen YZ, et al. . Boosting neutral water oxidation through surface oxygen modulation. Adv. Mater., 2020, 322002297

[12] Jiang N, Zhu ZW, Xue WJ, et al. . Emerging electrocatalysts for water oxidation under near-neutral CO₂ reduction conditions. Adv. Mater., 2022, 342105852

[13] Xie, W.F., Li, B.K., Liu, L., et al.: Advanced systems for enhanced CO₂ electroreduction. Chem. Soc. Rev. 54, 898–959 (2025). https://doi.org/10.1039/D4CS00563E

[14] Lai, W.C., Qiao, Y., Zhang, J.W., et al.: Design strategies for markedly enhancing energy efficiency in the electrocatalytic CO₂ reduction reaction. Energy Environ. Sci. 15, 3603–3629 (2022). https://doi.org/10.1039/D2EE00472K

[15] Ozden A, García de Arquer FP, Huang JE, et al. . Carbon-efficient carbon dioxide electrolysers. Nat. Sustain., 2022, 5: 563-573.

[16] Hong, P., Xu, C.F., Zhao, H.P., et al.: Atomic size misfit for electrocatalytic small molecule activation. Adv. Funct. Mater. 2502833 (2025). https://doi.org/10.1002/adfm.202502833

[17] Cao CS, Ma DD, Jia JC, et al. . Divergent paths, same goal: a pair-electrosynthesis tactic for cost-efficient and exclusive formate production by metal–organic-framework-derived 2D electrocatalysts. Adv. Mater., 2021, 332008631

[18] Houache, M.S.E., Safari, R., Nwabara, U.O., et al.: Selective electrooxidation of glycerol to formic acid over carbon supported Ni_1–xM_x (M = Bi, Pd, and Au) nanocatalysts and coelectrolysis of CO₂. ACS Appl. Energy Mater. 3, 8725–8738 (2020). https://doi.org/10.1021/acsaem.0c01282

[19] Liu ST, Tian BL, Xu XR, et al. . Ampere-level electrolytic coproduction of formate with coupled carbon dioxide reduction and selective methanol oxidation. ACS Catal., 2024, 14: 9476-9486.

[20] Zhou, Y.S., Wang, Z.W., Fang, W.S., et al.: Modulating O-H activation of methanol oxidation on nickel-organic frameworks for overall CO₂ electrolysis. ACS Catal. 13, 2039–2046 (2023). https://doi.org/10.1021/acscatal.2c05144

[21] Llorente MJ, Nguyen BH, Kubiak CP, et al. . Paired electrolysis in the simultaneous production of synthetic intermediates and substrates. J. Am. Chem. Soc., 2016, 138: 15110-15113.

[22] Yang YC, Mu TC. Electrochemical oxidation of biomass derived 5-hydroxymethylfurfural (HMF): pathway, mechanism, catalysts and coupling reactions. Green Chem., 2021, 23: 4228-4254.

[23] Li SQ, Sun X, Yao ZH, et al. . Biomass valorization via paired electrosynthesis over vanadium nitride-based electrocatalysts. Adv. Funct. Mater., 2019, 291904780

[24] Pan WF, Yuan J, Wang P, et al. . Efficient ultra-low voltage electrolysis of CO₂ coupling with hydrazine oxidation degradation. Appl. Catal. B Environ. Energy, 2024, 351124011

[25] Hu CH, Zhang Y, Hu AQ, et al. . Near- and long-range electronic modulation of single metal sites to boost CO₂ electrocatalytic reduction. Adv. Mater., 2023, 352209298

[26] Yang XX, Mukherjee S, O’Carroll T, et al. . Achievements, challenges, and perspectives on nitrogen electrochemistry for carbon-neutral energy technologies. Angew. Chem. Int. Ed., 2023, 62e202215938

[27] Digdaya IA, Sullivan I, Lin M, et al. . A direct coupled electrochemical system for capture and conversion of CO₂ from oceanwater. Nat. Commun., 2020, 114412

[28] Exner KS. Controlling stability and selectivity in the competing chlorine and oxygen evolution reaction over transition metal oxide electrodes. ChemElectroChem, 2019, 6: 3401-3409.

[29] Leow WR, Lum Y, Ozden A, et al. . Chloride-mediated selective electrosynthesis of ethylene and propylene oxides at high current density. Science, 2020, 368: 1228-1233.

[30] Zhang JY, Wang HM, Tian YF, et al. . Anodic hydrazine oxidation assists energy-efficient hydrogen evolution over a bifunctional cobalt perselenide nanosheet electrode. Angew. Chem.-Int. Edit., 2018, 57: 7649-7653.

[31] Zhu BJ, Liang ZB, Zou RQ. Designing advanced catalysts for energy conversion based on urea oxidation reaction. Small, 2020, 161906133

[32] Tan HW, Abdul Aziz AR, Aroua MK. Glycerol production and its applications as a raw material: a review. Renew. Sustain. Energy Rev., 2013, 27: 118-127.

[33] van Putten RJ, van der Waal JC, de Jong E, et al. . Hydroxymethylfurfural, a versatile platform chemical made from renewable resources. Chem. Rev., 2013, 113: 1499-1597.

[34] Wang QN, Zhu CQ, Wu C, et al. . Direct synthesis of bismuth nanosheets on a gas diffusion layer as a high-performance cathode for a coupled electrochemical system capable of electroreduction of CO₂ to formate with simultaneous degradation of organic pollutants. Electrochim. Acta, 2019, 319: 138-147.

[35] Bharath, G., Rambabu, K., Aubry, C., et al.: Self-assembled Co₃O₄ nanospheres on N-doped reduced graphene oxide (Co₃O₄/N-RGO) bifunctional electrocatalysts for cathodic reduction of CO₂ and anodic oxidation of organic pollutants. ACS Appl. Energy Mater. 4, 11408–11418 (2021). https://doi.org/10.1021/acsaem.1c02196

[36] Ma WG, Wang H, Yu W, et al. . Achieving simultaneous CO₂ and H₂S conversion via a coupled solar-driven electrochemical approach on non-precious-metal catalysts. Angew. Chem.-Int. Edit., 2018, 57: 3473-3477.

[37] Xiao, L., Dai, W.D., Mou, S.Y., et al.: Coupling electrocatalytic cathodic nitrate reduction with anodic formaldehyde oxidation at ultra-low potential over Cu₂O. Energy Environ. Sci. 16, 2696–2704 (2023). https://doi.org/10.1039/D3EE00635B

[38] An SY, Zhao ZH, Bu J, et al. . Multi-functional formaldehyde-nitrate batteries for wastewater refining, electricity generation, and production of ammonia and formate. Angew. Chem.-Int. Edit., 2024, 63e202318989

[39] Yu WQ, Wang YJ, Tan H, et al. . Current state and future prospects of environmentally catalytic Zn-NO_x batteries. Adv. Energy Mater., 2024, 142402970

[40] Xu, C.F., Hong, P., Dong, Y.L., et al.: Toward complete CO₂ electroconversion: status, challenges, and perspectives. Adv. Energy Mater. 2406146 (2025). https://doi.org/10.1002/aenm.202406146

[41] Mao QQ, Mu X, Wang WX, et al. . Atomically dispersed Cu coordinated Rh metallene arrays for simultaneously electrochemical aniline synthesis and biomass upgrading. Nat. Commun., 2023, 145679

[42] Hao LL, Ren QH, Yang JR, et al. . Promoting electrocatalytic hydrogenation of oxalic acid to glycolic acid via an Al³⁺ ion adsorption strategy coupled with ethylene glycol oxidation. ACS Appl. Mater. Interfaces, 2023, 15: 13176-13185.

[43] Yang GC, Jiao YQ, Yan HJ, et al. . Unraveling the mechanism for paired electrocatalysis of organics with water as a feedstock. Nat. Commun., 2022, 133125

[44] Vass Á, Endrődi B, Janáky C. Coupling electrochemical carbon dioxide conversion with value-added anode processes: an emerging paradigm. Curr. Opin. Electrochem., 2021, 25100621

[45] Xi WL, Yang P, Jiang MK, et al. . Electrochemical CO₂ reduction coupled with alternative oxidation reactions: electrocatalysts, electrolytes, and electrolyzers. Appl. Catal. B Environ., 2024, 341123291

[46] Qin YX, Wang YY, Jin GQ, et al. . Construction and progress of small molecule-based coupled electrolyzers. Adv. Energy Mater., 2024, 142402429

[47] Tan, X.Y., Yu, C., Ren, Y.W., et al.: Recent advances in innovative strategies for the CO₂ electroreduction reaction. Energy Environ. Sci. 14, 765–780 (2021). https://doi.org/10.1039/D0EE02981E

[48] Coutanceau C, Baranton S, Kouamé RSB. Selective electrooxidation of glycerol into value-added chemicals: a short overview. Front. Chem., 2019, 7100

[49] Verma S, Lu S, Kenis PJA. Co-electrolysis of CO₂ and glycerol as a pathway to carbon chemicals with improved technoeconomics due to low electricity consumption. Nat. Energy, 2019, 4: 466-474.

[50] Bevilacqua M, Filippi J, Lavacchi A, et al. . Energy savings in the conversion of CO₂ to fuels using an electrolytic device. Energy Technol., 2014, 2: 522-525.

[51] Li, T.F., Cao, Y., He, J.F., et al.: Electrolytic CO₂ reduction in tandem with oxidative organic chemistry. ACS Cent. Sci. 3, 778–783 (2017). https://doi.org/10.1021/acscentsci.7b00207

[52] Jing YX, Guo Y, Xia QN, et al. . Catalytic production of value-added chemicals and liquid fuels from lignocellulosic biomass. Chem, 2019, 5: 2520-2546.

[53] Miao ZL, Xu CF, Zhan J, et al. . Morphology-control and template-free fabrication of bimetallic Cu–Ni alloy rods for ethanol electro-oxidation in alkaline media. J. Alloys Compd., 2021, 855157438

[54] Fan JL, Liu SB, Chen ML, et al. . Electrochemical reduction of nitrate to ammonia on ultra-stable amorphous Co–P electrocatalyst. J. Mater. Chem. A, 2024, 12: 20077-20087.

[55] Gong MY, Cao CS, Zhu QL. Paired electrosynthesis design strategy for sustainable CO₂ conversion and product upgrading. Energychem, 2023, 5100111

[56] Wang HY, Ren JT, Sun ML, et al. . Value-added aqueous metal-redox bicatalyst batteries. Adv. Energy Mater., 2024, 142302515

[57] Xu CF, Hong P, Dong YL, et al. . Multiscale defective interfaces for realizing Na-CO₂ batteries with ultralong lifespan. Adv. Mater., 2024, 362409533

[58] Dong YL, Xu CF, Fu YH, et al. . Catalyzed carbon-based materials for CO₂-battery utilization. Energy Mater., 2025, 5500039

[59] Ye FH, Zhang SS, Cheng QQ, et al. . The role of oxygen-vacancy in bifunctional indium oxyhydroxide catalysts for electrochemical coupling of biomass valorization with CO₂ conversion. Nat. Commun., 2023, 142040

[60] Li Y, Huo CZ, Wang HJ, et al. . Coupling CO₂ reduction with CH₃OH oxidation for efficient electrosynthesis of formate on hierarchical bifunctional CuSn alloy. Nano Energy, 2022, 98107277

[61] Lees EW, Mowbray BAW, Parlane FGL, et al. . Gas diffusion electrodes and membranes for CO₂ reduction electrolysers. Nat. Rev. Mater., 2022, 7: 55-64.

[62] Bui JC, Lees EW, Marin DH, et al. . Multi-scale physics of bipolar membranes in electrochemical processes. Nat. Chem. Eng., 2024, 1: 45-60.

[63] Xu, Z.A., Wan, L., Liao, Y.W., et al.: Continuous ammonia electrosynthesis using physically interlocked bipolar membrane at 1 000 mA cm⁻². Nat. Commun. 14, 1619 (2023). https://doi.org/10.1038/s41467-023-37273-7

[64] Xie Y, Ou PF, Wang X, et al. . High carbon utilization in CO₂ reduction to multi-carbon products in acidic media. Nat. Catal., 2022, 5: 564-570.

[65] Huang JE, Li FW, Ozden A, et al. . CO₂ electrolysis to multicarbon products in strong acid. Science, 2021, 372: 1074-1078.

[66] Zi X, Zhou YJ, Zhu L, et al. . Breaking K⁺ concentration limit on Cu nanoneedles for acidic electrocatalytic CO₂ reduction to multi-carbon products. Angew. Chem.-Int. Edit., 2023, 62e202309351

[67] Li SJ, Dong X, Wu GF, et al. . Ampere-level CO₂ electroreduction with single-pass conversion exceeding 85% in acid over silver penetration electrodes. Nat. Commun., 2024, 156101

[68] Li SF, Zhou YY, Fu XB, et al. . Long-term continuous ammonia electrosynthesis. Nature, 2024, 629: 92-97.

[69] Fan GL, Xu WC, Li JH, et al. . Enhancing electrocatalytic nitrogen reduction on few-layer antimonene in an aqueous potassium sulfate electrolyte. J. Phys. Chem. C, 2022, 126: 13629-13639.

[70] Wang J, Yu L, Hu L, et al. . Ambient ammonia synthesis via palladium-catalyzed electrohydrogenation of dinitrogen at low overpotential. Nat. Commun., 2018, 91795

[71] Xie JF, Huang YY, Wu MX, et al. . Electrochemical carbon dioxide splitting. ChemElectroChem, 2019, 6: 1587-1604.

[72] Kang CSM, Zhang XY, MacFarlane DR. High nitrogen gas solubility and physicochemical properties of [C₄mpyr] [eFAP]–fluorinated solvent mixtures. J. Phys. Chem. C, 2019, 123: 21376-21385.

[73] Gao DF, Wei PF, Li HF, et al. . Designing electrolyzers for electrocatalytic CO₂ reduction. Acta Phys. Chim. Sin., 2020, 37: 2009021.

[74] Lin J, Yan SL, Zhang CX, et al. . Electroreduction of CO₂ toward high current density. Processes, 2022, 10826

[75] Ma SC, Sadakiyo M, Luo R, et al. . One-step electrosynthesis of ethylene and ethanol from CO₂ in an alkaline electrolyzer. J. Power. Sources, 2016, 301: 219-228.

[76] Lee J, Lim J, Roh CW, et al. . Electrochemical CO₂ reduction using alkaline membrane electrode assembly on various metal electrodes. J. CO2 Util., 2019, 31: 244-250.

[77] Reyes, A., Jansonius, R.P., Mowbray, B.A.W., et al.: Managing hydration at the cathode enables efficient CO₂ electrolysis at commercially relevant current densities. ACS Energy Lett. 5, 1612–1618 (2020). https://doi.org/10.1021/acsenergylett.0c00637

[78] Yin, Z.L., Peng, H.Q., Wei, X., et al.: An alkaline polymer electrolyte CO₂ electrolyzer operated with pure water. Energy Environ. Sci. 12, 2455–2462 (2019). https://doi.org/10.1039/C9EE01204D

[79] Jeong, H.Y., Balamurugan, M., Choutipalli, V.S.K., et al.: Achieving highly efficient CO₂ to CO electroreduction exceeding 300 mA cm⁻² with single-atom nickel electrocatalysts. J. Mater. Chem. A 7, 10651–10661 (2019). https://doi.org/10.1039/C9TA02405K

[80] Xia C, Zhu P, Jiang Q, et al. . Continuous production of pure liquid fuel solutions via electrocatalytic CO₂ reduction using solid-electrolyte devices. Nat. Energy, 2019, 4: 776-785.

[81] Yap FM, Loh JY, Ng SF, et al. . Self-supported earth-abundant carbon-based substrates in electrocatalysis landscape: unleashing the potentials toward paving the way for water splitting and alcohol oxidation. Adv. Energy Mater., 2024, 142303614

[82] Arshad F, Haq TU, Hussain I, et al. . Recent advances in electrocatalysts toward alcohol-assisted, energy-saving hydrogen production. ACS Appl. Energy Mater., 2021, 4: 8685-8701.

[83] Wang P, Zheng J, Xu X, et al. . Unlocking efficient hydrogen production: nucleophilic oxidation reactions coupled with water splitting. Adv. Mater., 2024, 362404806

[84] Wei XF, Li Y, Chen LS, et al. . Formic acid electro-synthesis by concurrent cathodic CO₂ reduction and anodic CH₃OH oxidation. Angew. Chem.-Int. Edit., 2021, 60: 3148-3155.

[85] Sun SN, Dong LZ, Li JR, et al. . Redox-active crystalline coordination catalyst for hybrid electrocatalytic methanol oxidation and CO₂ reduction. Angew. Chem.-Int. Edit., 2022, 61e202207282

[86] Li, X., Chen, Q.S., Sun, W., et al.: Electron-efficient co-electrosynthesis of formates from CO₂ and methanol feedstocks. Angew. Chem. -Int. Edit. 63, e202412410 (2024). https://doi.org/10.1002/anie.202412410

[87] Hao SJ, Cong MY, Xu HW, et al. . Bismuth-based electrocatalysts for identical value-added formic acid through coupling CO₂ reduction and methanol oxidation. Small, 2024, 202307741

[88] Fu GD, Kang XM, Zhang Y, et al. . Coordination effect-promoted durable Ni(OH)₂ for energy-saving hydrogen evolution from water/methanol co-electrocatalysis. Nano-Micro Lett., 2022, 14200

[89] Hao J, Liu JW, Wu D, et al. . In situ facile fabrication of Ni(OH)₂ nanosheet arrays for electrocatalytic co-production of formate and hydrogen from methanol in alkaline solution. Appl. Catal. B Environ., 2021, 281119510

[90] Li JS, Xing CC, Zhang Y, et al. . Nickel iron diselenide for highly efficient and selective electrocatalytic conversion of methanol to formate. Small, 2021, 172006623

[91] Xu Y, Liu MY, Wang MZ, et al. . Methanol electroreforming coupled to green hydrogen production over bifunctional NiIr-based metal-organic framework nanosheet arrays. Appl. Catal. B Environ., 2022, 300120753

[92] Guo L, Zhang XX, Gan L, et al. . Advances in selective electrochemical oxidation of 5-hydroxymethylfurfural to produce high-value chemicals. Adv. Sci., 2023, 102205540

[93] Yang ZW, Chen JM, Liang ZL, et al. . Anodic product-derived Bi-MOF as pre-catalyst for cathodic CO₂ reduction: a novel strategy for paired electrolysis. ChemCatChem, 2023, 15e202201321

[94] Choi, S., Balamurugan, M., Lee, K.G., et al.: Mechanistic investigation of biomass oxidation using nickel oxide nanoparticles in a CO₂-saturated electrolyte for paired electrolysis. J. Phys. Chem. Lett. 11, 2941–2948 (2020). https://doi.org/10.1021/acs.jpclett.0c00425

[95] Bi, J.H., Zhu, Q.G., Guo, W.W., et al.: Simultaneous CO₂ reduction and 5-hydroxymethylfurfural oxidation to value-added products by electrocatalysis. ACS Sustainable Chem. Eng. 10, 8043–8050 (2022). https://doi.org/10.1021/acssuschemeng.2c02117

[96] Li MH, Wang HF, Luo W, et al. . Heterogeneous single-atom catalysts for electrochemical CO₂ reduction reaction. Adv. Mater., 2020, 322001848

[97] Liu, S.Q., Gao, M.R., Wu, S.W., et al.: A coupled electrocatalytic system with reduced energy input for CO₂ reduction and biomass valorization. Energy Environ. Sci. 16, 5305–5314 (2023). https://doi.org/10.1039/D3EE01999C

[98] Cao XY, Tian YD, Ma JZ, et al. . Strong p-d orbital hybridization on bismuth nanosheets for high performing CO₂ electroreduction. Adv. Mater., 2024, 362309648

[99] Zhang, Z.H., Liu, S., Wu, Z., et al.: High efficiency coupled electrocatalytic CO₂ reduction to C₂H₄ with 5-hydroxymethylfurfural oxidation over Cu-based nanoflower electrocatalysts. Green Chem. 25, 5404–5415 (2023). https://doi.org/10.1039/D3GC01420G

[100] Kumawat S, Singh S, Bhatt T, et al. . Valorization of bio-renewable glycerol by catalytic amination reactions. Green Chem., 2024, 26: 3021-3038.

[101] Fan LF, Liu BW, Liu X, et al. . Recent progress in electrocatalytic glycerol oxidation. Energy Technol., 2021, 9: 2000804

[102] Dodekatos G, Schünemann S, Tüysüz H. Recent advances in thermo-, photo-, and electrocatalytic glycerol oxidation. ACS Catal., 2018, 8: 6301-6333.

[103] Guo, X.Y., Xu, S.M., Zhou, H., et al.: Engineering hydrogen generation sites to promote electrocatalytic CO₂ reduction to formate. ACS Catal. 12, 10551–10559 (2022). https://doi.org/10.1021/acscatal.2c02548

[104] Pei, Y.H., Pi, Z.F., Zhong, H., et al.: Glycerol oxidation-assisted electrochemical CO₂ reduction for the dual production of formate. J. Mater. Chem. A 10, 1309–1319 (2022). https://doi.org/10.1039/D1TA07119J

[105] Junqueira JRC, Das D, Cathrin Brix A, et al. . Simultaneous anodic and cathodic formate production in a paired electrolyzer by CO₂ reduction and glycerol oxidation. Chemsuschem, 2023, 16e202202349

[106] Wang GX, Chen JX, Li KK, et al. . Cost-effective and durable electrocatalysts for co-electrolysis of CO₂ conversion and glycerol upgrading. Nano Energy, 2022, 92106751

[107] Besson M, Gallezot P, Pinel C. Conversion of biomass into chemicals over metal catalysts. Chem. Rev., 2014, 114: 1827-1870.

[108] Xie K, Ozden A, Miao RK, et al. . Eliminating the need for anodic gas separation in CO₂ electroreduction systems via liquid-to-liquid anodic upgrading. Nat. Commun., 2022, 133070

[109] Ben Aoun S, Dursun Z, Koga T, et al. . Effect of metal ad-layers on Au(1 1 1) electrodes on electrocatalytic oxidation of glucose in an alkaline solution. J. Electroanal. Chem., 2004, 567: 175-183.

[110] Zhao RY, Wang YD, Ji GP, et al. . Coupling electrocatalytic CO₂ reduction with glucose oxidation for concurrent production of formate with high efficiency. Chem. Eng. J., 2024, 486150280

[111] Ghosh S, Bagchi D, Mondal I, et al. . Deciphering the role of nickel in electrochemical organic oxidation reactions. Adv. Energy Mater., 2024, 142400696

[112] Liang Y, Zhou W, Shi YM, et al. . Unveiling in situ evolved In/In₂O_3−x heterostructure as the active phase of In₂O₃ toward efficient electroreduction of CO₂ to formate. Sci. Bull., 2020, 65: 1547-1554.

[113] Zhu ZH, Liang ZL, Hou SL, et al. . Efficient CO₂ electroreduction coupled with semi-dehydrogenation of tetrahydroisoquinoline by MOFs modified electrodes. J. Energy Chem., 2021, 63: 328-335.

[114] Cao XY, Wang YQ, Tan DX, et al. . Stepwise dispersion of nickel species for efficient coupling of electrocatalytic redox reactions. Chem. Eng. J., 2023, 454140062

[115] Fan L, Xia C, Zhu P, et al. . Electrochemical CO₂ reduction to high-concentration pure formic acid solutions in an all-solid-state reactor. Nat. Commun., 2020, 11: 3633

[116] Jiang XY, Ke L, Zhao K, et al. . Integrating hydrogen utilization in CO₂ electrolysis with reduced energy loss. Nat. Commun., 2024, 151427

[117] Fang WS, Guo W, Lu RH, et al. . Durable CO₂ conversion in the proton-exchange membrane system. Nature, 2024, 626: 86-91.

[118] Mostafa E, Reinsberg P, Garcia-Segura S, et al. . Chlorine species evolution during electrochlorination on boron-doped diamond anodes: in-situ electrogeneration of Cl₂, Cl₂O and ClO₂. Electrochim. Acta, 2018, 281: 831-840.

[119] Quan, F.J., Zhan, G.M., Shang, H., et al.: Highly efficient electrochemical conversion of CO₂ and NaCl to CO and NaClO. Green Chem. 21, 3256–3262 (2019). https://doi.org/10.1039/C9GC01099H

[120] Ge R, Dong LY, Hu X, et al. . Intensified coupled electrolysis of CO₂ and brine over electrocatalysts with ordered mesoporous transport channels. Chem. Eng. J., 2022, 438135500

[121] Kang, C.T., Li, Y.M., Xu, Y.Z., et al.: Coupling CO₂-to-ethylene reduction with the chlor-alkaline process in seawater through in situ-formed Cu catalysts. J. Phys. Chem. Lett. 14, 2983–2989 (2023). https://doi.org/10.1021/acs.jpclett.3c00179

[122] Gupta NK, Peng B, Haller GL, et al. . Nitrogen modified carbon nano-materials as stable catalysts for phosgene synthesis. ACS Catal., 2016, 6: 5843-5855.

[123] Tan XY, Yu C, Song XD, et al. . Toward an understanding of the enhanced CO₂ electroreduction in NaCl electrolyte over CoPc molecule-implanted graphitic carbon nitride catalyst. Adv. Energy Mater., 2021, 11: 2100075

[124] Varela AS, Ju W, Strasser P. Molecular nitrogen–carbon catalysts, solid metal organic framework catalysts, and solid metal/nitrogen-doped carbon (MNC) catalysts for the electrochemical CO₂ reduction. Adv. Energy Mater., 2018, 81703614

[125] Guo JH, Sun WY. Integrating nickel-nitrogen doped carbon catalyzed CO₂ electroreduction with chlor-alkali process for CO, Cl₂ and KHCO₃ production with enhanced techno-economics. Appl. Catal. B-Environ., 2020, 275119154

[126] Kumar P, Srivastava VC, Štangar UL, et al. . Recent progress in dimethyl carbonate synthesis using different feedstock and techniques in the presence of heterogeneous catalysts. Catal. Rev., 2021, 63: 363-421.

[127] Min L, Ho J, Balamurugan M, et al. . Redox-neutral electrochemical conversion of CO₂ to dimethyl carbonate. Nat. Energy, 2021, 6: 733-741.

[128] Li, X.F., Han, S.G., Wu, W.M., et al.: Convergent paired electrosynthesis of dimethyl carbonate from carbon dioxide enabled by designing the superstructure of axial oxygen coordinated nickel single-atom catalysts. Energy Environ. Sci. 16, 502–512 (2023). https://doi.org/10.1039/D2EE03022E

[129] Chang ZW, Kong FT, Wang M, et al. . Efficient ammonia electrosynthesis by coupling to concurrent methanol oxidation. Chem. Catal., 2022, 2: 358-371.

[130] Gupta D, Kafle A, Nagaiah TC. Dinitrogen reduction coupled with methanol oxidation for low overpotential electrochemical NH₃ synthesis over cobalt pyrophosphate as bifunctional catalyst. Small, 2023, 192208272

[131] Wang ZY, Chang JL, Gao ZY. Ammonia and formate cosynthesis via nitrate electroreduction combined with methanol electrooxidation over nitrogen-doped carbon-encapsulated nickel iron phosphide. Inorg. Chem. Front., 2024, 11: 8876-8889.

[132] Zhao YJ, Bao ZY, Bai XW, et al. . Superior electrocatalytic nitrate-to-ammonia conversion activity on CuCo bimetals in neutral media. Appl. Catal. B-Environ. Energy, 2024, 357124294

[133] Zhang L, Jin PY, Wu Z, et al. . CuO/Co₃O₄ bifunctional catalysts for electrocatalytic 5-hydroxymethylfurfural oxidation coupled cathodic ammonia production. Energy Environ. Mater., 2024, 7e12725

[134] Wordsworth J, Benedetti TM, Somerville SV, et al. . The influence of nanoconfinement on electrocatalysis. Angew. Chem.- Int. Edit., 2022, 61e202200755

[135] Han, C.Y., Sun, L.Z., Han, S., et al.: Stabilizing hydrogen radicals in two-dimensional cobalt-copper mesoporous nanoplates for complete nitrate reduction electrocatalysis to ammonia. Angew. Chem.-Int. Edit. 64, e202416910 (2025). https://doi.org/10.1002/anie.202416910

[136] Su ZF, Liu KK, Xu YQ, et al. . Charge manipulation of porous coordination cages tunes the efficiency and selectivity in electrochemical synthesis. Angew. Chem. Int. Ed., 2025, 64e202420945

[137] Li SL, Ma PJ, Gao CL, et al. . Reconstruction-induced NiCu-based catalysts towards paired electrochemical refining. Energy Environ. Sci., 2022, 15: 3004-3014.

[138] Zhu HB, Wang JJ, Xu ZA, et al. . Pd nanoparticle size-dependent H* coverage for Cu-catalyzed nitrate electro-reduction to ammonia in neutral electrolyte. Small, 2024, 20: 2404919

[139] Wu XH, Zhao ZJ, Shi XC, et al. . Multi-site catalysis of high-entropy hydroxides for sustainable electrooxidation of glucose to glucaric acid. Energy Environ. Sci., 2024, 17: 3042-3051.

[140] Chaturvedi, A., Gupta, D., Kaur, S., et al.: Glucose oxidation assisted ammonia production via electrochemical dinitrogen reduction over CoWO₄. J. Mater. Chem. A 11, 18280–18290 (2023). https://doi.org/10.1039/D3TA03302C

[141] Chaturvedi A, Gaber S, Kaur S, et al. . Covalent organic framework bifunctional catalyst for glucose oxidation reaction coupled nitrate to ammonia electrolysis. ACS Energy Lett., 2024, 9: 2484-2491.

[142] Andersen SZ, Čolić V, Yang S, et al. . A rigorous electrochemical ammonia synthesis protocol with quantitative isotope measurements. Nature, 2019, 570: 504-508.

[143] Li SF, Fu XB, Nørskov JK, et al. . Towards sustainable metal-mediated ammonia electrosynthesis. Nat. Energy, 2024, 9: 1344-1349.

[144] Fu XB, Pedersen JB, Zhou YY, et al. . Continuous-flow electrosynthesis of ammonia by nitrogen reduction and hydrogen oxidation. Science, 2023, 379: 707-712.

[145] Ügdüler S, Van Geem KM, Denolf R, et al. . Towards closed-loop recycling of multilayer and coloured PET plastic waste by alkaline hydrolysis. Green Chem., 2020, 22: 5376-5394.

[146] Wang JY, Li X, Zhang T, et al. . Electro-reforming polyethylene terephthalate plastic to co-produce valued chemicals and green hydrogen. J. Phys. Chem. Lett., 2022, 13: 622-627.

[147] Wang JY, Li X, Wang ML, et al. . Electrocatalytic valorization of poly(ethylene terephthalate) plastic and CO₂ for simultaneous production of formic acid. ACS Catal., 2022, 12: 6722-6728.

[148] Ma FH, Li ZQ, Hu RM, et al. . Electrocatalytic waste-treating-waste strategy for concurrently upgrading of polyethylene terephthalate plastic and CO₂ into value-added formic acid. ACS Catal., 2023, 13: 14163-14172.

[149] Santos S, Jones K, Abdul R, et al. . Treatment of wet process hardboard plant VOC emissions by a pilot scale biological system. Biochem. Eng. J., 2007, 37: 261-270.

[150] Zhang H, Guo GH, Wang ZY, et al. . Superior performance of formaldehyde complete oxidation at ambient temperature over Co single-atom catalysts. Appl. Catal. B-Environ. Energy, 2023, 333122774

[151] Li MY, Wang TH, Zhao WX, et al. . A pair-electrosynthesis for formate at ultra-low voltage via coupling of CO₂ reduction and formaldehyde oxidation. Nano-Micro Lett., 2022, 14211

[152] Lv XD, Liu JY, Shao T, et al. . Efficient and cost-effective electrocatalytic CO₂ to CO reduction over Sn-modified Cu nanowires by pairing with selective HCHO to HCOOH oxidation. Catal. Today, 2023, 420114188

[153] Zhang, M., Wang, X.Y., Ding, J.J., et al.: Realizing ampere-level CO₂ electrolysis at low voltage over a woven network of few-atom-layer ultralong silverene nanobelts with ultrahigh aspect ratio by pairing with formaldehyde oxidation. Nanoscale 16, 7076–7084 (2024). https://doi.org/10.1039/D4NR00361F

[154] Gupta AK, Ibrahim S, Al Shoaibi A. Advances in sulfur chemistry for treatment of acid gases. Prog. Energy Combust. Sci., 2016, 54: 65-92.

[155] Blázquez E, Gabriel D, Baeza JA, et al. . Treatment of high-strength sulfate wastewater using an autotrophic biocathode in view of elemental sulfur recovery. Water Res., 2016, 105: 395-405.

[156] Vaiopoulou E, Provijn T, Prévoteau A, et al. . Electrochemical sulfide removal and caustic recovery from spent caustic streams. Water Res., 2016, 92: 38-43.

[157] Zhang, B., Bai, J., Zhang, Y., et al.: High yield of CO and synchronous S recovery from the conversion of CO₂ and H₂S in natural gas based on a novel electrochemical reactor. Environ. Sci. Technol. 55, 14854–14862 (2021). https://doi.org/10.1021/acs.est.1c04414

[158] Yang KX, Zhang N, Yang JF, et al. . Synergistic marriage of CO₂ reduction and sulfide oxidation towards a sustainable co-electrolysis process. Appl. Catal. B Environ., 2023, 332122718

[159] Teng X, Shi K, Chen LS, et al. . Coupling electrochemical sulfion oxidation with CO₂ reduction over highly dispersed p-Bi nanosheets and CO₂-assisted sulfur extraction. Angew. Chem.-Int. Edit., 2024, 63e202318585

[160] Medvedeva, X.V., Medvedev, J.J., Tatarchuk, S.W., et al.: Sustainable at both ends: electrochemical CO₂ utilization paired with electrochemical treatment of nitrogenous waste. Green Chem. 22, 4456–4462 (2020). https://doi.org/10.1039/D0GC01754J

[161] Wang LP, Zhu YJ, Wen YZ, et al. . Regulating the local charge distribution of Ni active sites for the urea oxidation reaction. Angew. Chem. Int. Ed., 2021, 60: 10577-10582.

[162] Choi M, Kim JW, Chung S, et al. . Syngas production for Fischer-Tropsch process via co-electrolytic processes of CO₂ reduction and NH₃ oxidation. Chem. Eng. J., 2022, 430132563

[163] Zhang YR, Yang N, Murugananthan M, et al. . Electrochemical degradation of PNP at boron-doped diamond and platinum electrodes. J. Hazard. Mater., 2013

[164] Zou JP, Chen Y, Liu SS, et al. . Electrochemical oxidation and advanced oxidation processes using a 3D hexagonal Co₃O₄ array anode for 4-nitrophenol decomposition coupled with simultaneous CO₂ conversion to liquid fuels via a flower-like CuO cathode. Water Res., 2019, 150: 330-339.

[165] Zhu M, Zhang LS, Liu SS, et al. . Degradation of 4-nitrophenol by electrocatalysis and advanced oxidation processes using Co₃O₄@C anode coupled with simultaneous CO₂ reduction via SnO₂/CC cathode. Chin. Chem. Lett., 2020, 31: 1961-1965.

[166] Guo CY, He P, Cui RR, et al. . Electrochemical CO₂ reduction using electrons generated from photoelectrocatalytic phenol oxidation. Adv. Energy Mater., 2019, 91900364

[167] Wang, Q.N., Wang, W.L., Zhu, C.Q., et al.: A novel strategy to achieve simultaneous efficient formate production and p-nitrophenol removal in a co-electrolysis system of CO₂ and p-nitrophenol. J. CO₂ Util. 47, 101497 (2021). https://doi.org/10.1016/j.jcou.2021.101497

[168] Wang, Q.N., Wang, X.Q., Wu, C., et al.: Enhanced electroreduction of CO₂ and simultaneous degradation of organic pollutants using a Sn-based carbon nanotubes/carbon black hybrid gas diffusion cathode. J. CO₂ Util. 26, 425–433 (2018). https://doi.org/10.1016/j.jcou.2018.05.027

[169] Kim BJ, Piao GX, Kim S, et al. . High-efficiency solar desalination accompanying electrocatalytic conversions of desalted chloride and captured carbon dioxide. ACS Sustain. Chem. Eng., 2019, 7: 15320-15328.

[170] Choi W, Kim M, Kim BJ, et al. . Electrocatalytic arsenite oxidation in bicarbonate solutions combined with CO₂ reduction to formate. Appl. Catal. B-Environ., 2020, 265118607

[171] Ren TL, Yu Z, Yu HJ, et al. . Sustainable ammonia electrosynthesis from nitrate wastewater coupled to electrocatalytic upcycling of polyethylene terephthalate plastic waste. ACS Nano, 2023, 17: 12422-12432.

[172] Yang S, Cai CC, Sun JY, et al. . Photovoltaic-driven electro-reforming of poly (ethylene terephthalate) (PET) waste plastics and nitrate pollutants. Chem. Eng. Sci., 2024, 295120186

[173] Wang Z, Zhou N, Wang JZ, et al. . Highly efficient electrochemical ammonia synthesis via nitrate reduction over metallic Cu phase coupling sulfion oxidation. Chemsuschem, 2024, 17e202301050

[174] Yang MS, Wei TR, Zeng CH, et al. . CoNiOOH nanosheets array enables highly effective value-added chemicals production via nitrite and sulfide electrolysis. Chem. Eng. J., 2024, 498155799

[175] Wang XH, Hong QL, Shao LY, et al. . Copper–nickel oxide nanosheets with atomic thickness for high-efficiency sulfur ion electrooxidation assisted nitrate electroreduction to ammonia. Adv. Funct. Mater., 2024, 342408834

[176] Zhang CH, Wang XZ, Jiang J, et al. . Self-powered energy-efficient electrochemical nitrite reduction coupled with sulfion oxidation for ammonia synthesis and sulfur recovery over hierarchical cobalt sulfide nanostructures. Appl. Catal. B Environ. Energy, 2025, 365124991

[177] Sayed ET, Eisa T, Mohamed HO, et al. . Direct urea fuel cells: challenges and opportunities. J. Power. Sources, 2019, 417: 159-175.

[178] Fang C, Min B, Angelidaki I. Nitrate as an oxidant in the cathode chamber of a microbial fuel cell for both power generation and nutrient removal purposes. Appl. Biochem. Biotechnol., 2011, 164: 464-474.

[179] Nangan S, Ding YC, Alhakemy AZ, et al. . Hybrid alkali-acid urea-nitrate fuel cell for degrading nitrogen-rich wastewater. Appl. Catal. B-Environ., 2021, 286119892

[180] Lim C, Roh H, Kim EH, et al. . Energy-efficient and self-powered green ammonia synthesis by electrochemical nitrate reduction combined with hydrazine oxidation. Small, 2023, 192304274

[181] Gao SS, Wei TR, Sun JQ, et al. . Atomically dispersed metal-based catalysts for Zn-CO₂ batteries. Small Struct., 2022, 32200086

[182] Xu CF, Dong YL, Shen YL, et al. . Fundamental understanding of nonaqueous and hybrid Na-CO₂ batteries: challenges and perspectives. Small, 2023, 192206445

[183] Xu CF, Qiu JJ, Dong YL, et al. . Dual-functional electrode promoting dendrite-free and CO₂ utilization enabled high-reversible symmetric Na-CO₂ batteries. Energy Environ. Mater., 2024, 7e12626

[184] Xu CF, Wang HW, Zhan J, et al. . Engineering NH₃-induced 1D self-assembly architecture with conductive polymer for advanced hybrid Na-CO₂ batteries via morphology modulation. J. Power. Sources, 2022, 520230909

[185] Xu, C.F., Zhan, J., Wang, H.W., et al.: Dense binary Fe–Cu sites promoting CO₂ utilization enable highly reversible hybrid Na-CO₂ batteries. J. Mater. Chem. A 9, 22114–22128 (2021). https://doi.org/10.1039/D1TA06611K

[186] Xu C, Zhan J, Wang Z, et al. . Biomass-derived highly dispersed Co/Co₉S₈ nanoparticles encapsulated in S, N-co-doped hierarchically porous carbon as an efficient catalyst for hybrid Na-CO₂ batteries. Mater. Today Energy, 2021, 19100594

[187] Xu CF, Zhang KW, Zhang D, et al. . Reversible hybrid sodium-CO₂ batteries with low charging voltage and long-life. Nano Energy, 2020, 68104318

[188] Zhang Z, Wu SS, Yang C, et al. . Li-N2 batteries: a reversible energy storage system?. Angew. Chem. Int. Ed., 2019, 58: 17782-17787.

[189] Li JY, Du XY, Wang XX, et al. . Photo-assisted Li-N2 batteries with enhanced nitrogen fixation and energy conversion. Angew. Chem. Int. Ed., 2024, 63e202319211

[190] Xie, J.F., Wang, X.Y., Lv, J.Q., et al.: Reversible aqueous zinc–CO₂ batteries based on CO₂–HCOOH interconversion. Angew. Chem. -Int. Edit. 57, 16996–17001 (2018). https://doi.org/10.1002/anie.201811853

[191] Wang XY, Xie JF, Ghausi MA, et al. . Rechargeable Zn–CO₂ electrochemical cells mimicking two-step photosynthesis. Adv. Mater., 2019, 311807807

[192] Yang R, Peng Z, Xie JF, et al. . Reversible hybrid aqueous Li-CO₂ batteries with high energy density and formic acid production. Chemsuschem, 2020, 13: 2621-2627.

[193] Yang XC, Zhang DT, Zhao LQ, et al. . Upgrading cycling stability and capability of hybrid Na-CO₂ batteries via tailoring reaction environment for efficient conversion CO₂ to HCOOH (adv. energy mater. 16/2024). Adv. Energy Mater., 2024, 142470072

[194] Kang L, Zhang YH, Dong LH, et al. . Boron-doping engineering in AgCd bimetallic catalyst enabling efficient CO₂ electroreduction to CO and aqueous Zn-CO₂ batteries. Small, 2024, 202406510

[195] Miao KH, Qin JD, Lai SY, et al. . Spin regulation of nickel single atom catalyst via axial phosphor-coordination achieves near unity CO selectivity in electrochemical CO₂ reduction. Adv. Funct. Mater., 2025, 352419989

[196] Miao KH, Qin JD, Yang J, et al. . Synergy of Ni nanoclusters and single atom site: size effect on the performance of electrochemical CO₂ reduction reaction and rechargeable Zn-CO₂ batteries. Adv. Funct. Mater., 2024, 342316824

[197] Wang FY, Han XQ, Wu DX, et al. . Electron penetration effect of Ni single atom boosting CO₂ to CO in pH-universal electrolytes. Adv. Funct. Mater., 2024, 342314453

[198] Rao P, Han XQ, Sun HC, et al. . Precise synthesis of dual-single-atom electrocatalysts through pre-coordination-directed in situ confinement for CO₂ reduction. Angew. Chem.-Int. Edit., 2025, 64e202415223

[199] Gao SS, Liu YF, Xie ZY, et al. . Metal-free bifunctional ordered mesoporous carbon for reversible Zn-CO₂ batteries. Small Methods, 2021, 52001039

[200] Kaur S, Kumar M, Gupta D, et al. . Efficient CO₂ utilization and sustainable energy conversion via aqueous Zn-CO₂ batteries. Nano Energy, 2023, 109108242

[201] Wu WB, Tong Y, Ye YT, et al. . In-situ electrochemical transformation of F-modified metallic bismuth for highly-efficient CO₂ electroreduction and Zn–CO₂ battery. Chem. Eng. J., 2024, 494153105

[202] Aslam MK, Wang HR, Nie ZH, et al. . Unlock flow-type reversible aqueous Zn–CO₂ batteries. Mater. Horiz., 2024, 11: 2657-2666.

[203] Wang HJ, Zhu JY, Ren XH, et al. . Heterogeneous cobalt phthalocyanine/sulfur-modified hollow carbon sphere for boosting CO₂ electroreduction and Zn–CO₂ batteries. Adv. Funct. Mater., 2024, 342312552

[204] Bao YR, Xiao JY, Huang YK, et al. . Regulating spin polarization via axial nitrogen traction at Fe−N₅ sites enhanced electrocatalytic CO₂ reduction for Zn−CO₂ batteries. Angew. Chem. -Int. Edit., 2024, 63e202406030

[205] Han L, Wang CW, Xu HP, et al. . Red blood cell (RBC)-like Ni@N–C composites for efficient electrochemical CO₂ reduction and Zn–CO₂ batteries. J. Mater. Chem. A, 2024, 12: 9462-9468.

[206] Zeng ZP, Gan LY, Hong BY, et al. . Orbital coupling of hetero-diatomic nickel-iron site for bifunctional electrocatalysis of CO₂ reduction and oxygen evolution. Nat. Commun., 2021, 12: 4088

[207] Fu JJ, Zhao HX, Sui PF, et al. . Synergizing neighboring Fe single atom/cluster active sites anchored on porous graphitic nanospheres for high-performance CO₂ overall splitting and aqueous Zn-CO₂ batteries. Appl. Catal. B Environ. Energy, 2025, 365124967

[208] Wang K, Wu YY, Cao XB, et al. . A Zn–CO₂ flow battery generating electricity and methane. Adv. Funct. Mater., 2020, 301908965

[209] Liu YM, An Y, Zhu JX, et al. . Integrated energy storage and CO₂ conversion using an aqueous battery with tamed asymmetric reactions. Nat. Commun., 2024, 15977

[210] Gao SS, Li HY, Lu ZS, et al. . Isolated FeN3 sites anchored hierarchical porous carbon nanoboxes for hydrazine-assisted rechargeable Zn–CO₂ batteries with ultralow charge voltage. Carbon Energy, 2025, 7e637

[211] Kim, J., Lee, S., Kim, S., et al.: Anode-less hybrid Na-CO₂ battery with sodium harvesting from seawater for both electricity storage and various chemical production. ACS Energy Lett. 8, 5079–5087 (2023). https://doi.org/10.1021/acsenergylett.3c01977

[212] Du, C., Gao, Y.J., Wang, J.G., et al.: Achieving 59% faradaic efficiency of the N₂ electroreduction reaction in an aqueous Zn–N₂ battery by facilely regulating the surface mass transport on metallic copper. Chem. Commun. 55, 12801–12804 (2019). https://doi.org/10.1039/C9CC05978D

[213] Wang H, Si JC, Zhang TY, et al. . Exfoliated metallic niobium disulfate nanosheets for enhanced electrochemical ammonia synthesis and Zn-N₂ battery. Appl. Catal. B-Environ., 2020, 270118892

[214] Ren, J.T., Chen, L., Wang, H.Y., et al.: Aqueous rechargeable Zn–N₂ battery assembled by bifunctional cobalt phosphate nanocrystals-loaded carbon nanosheets for simultaneous NH₃ production and power generation. ACS Appl. Mater. Interfaces 13, 12106–12117 (2021). https://doi.org/10.1021/acsami.1c00570

[215] Ren, J.T., Chen, L., Liu, Y.P., et al.: Hollow cobalt phosphate microspheres for sustainable electrochemical ammonia production through rechargeable Zn–N₂ batteries. J. Mater. Chem. A 9, 11370–11380 (2021). https://doi.org/10.1039/D1TA01144H

[216] Meng FB, Xiong XY, He SN, et al. . Post nitrogen electrocatalysis era from Li–N₂ batteries to Zn–N₂ batteries. Adv. Energy Mater., 2023, 132300269

[217] Ren JT, Chen L, Wang HY, et al. . Aqueous Al-N₂ battery assembled by hollow molybdenum phosphate microspheres for simultaneous NH₃ production and power generation. Chem. Eng. J., 2021, 418129447

[218] Dai XY, Zhang W, Sun Y, et al. . Niobium oxide/MXene heterostructure for simultaneous production of ammonia and energy via rechargeable Zn–N₂ battery system. J. Energy Chem., 2025, 103: 448-457.

[219] Xu X, Zheng ZH, Zheng ML, et al. . Cooperation-doping cobalt and boron on MOF with double cone microrods structure to boost efficient nitrogen fixation in Zn–N₂ batteries. J. Energy Chem., 2025, 103: 465-475.

[220] Han LP, Cai SX, Gao M, et al. . Selective catalytic reduction of NO _x with NH ₃ by using novel catalysts: state of the art and future prospects. Chem. Rev., 2019, 119: 10916-10976.

[221] Serrano-Lotina A, Monte M, Iglesias-Juez A, et al. . MnO_x-support interactions in catalytic bodies for selective reduction of NO with NH₃. Appl. Catal. B-Environ., 2019, 256117821

[222] Long J, Chen SM, Zhang YL, et al. . Direct electrochemical ammonia synthesis from nitric oxide. Angew. Chem. Int. Ed., 2020, 59: 9711-9718.

[223] Rosca V, Duca M, de Groot MT, et al. . Nitrogen cycle electrocatalysis. Chem. Rev., 2009, 109: 2209-2244.

[224] Mou T, Liang J, Ma ZY, et al. . High-efficiency electrohydrogenation of nitric oxide to ammonia on a Ni₂P nanoarray under ambient conditions. J. Mater. Chem. A, 2021, 9: 24268-24275.

[225] Liang J, Chen HY, Mou T, et al. . Coupling denitrification and ammonia synthesis via selective electrochemical reduction of nitric oxide over Fe₂O₃ nanorods. J. Mater. Chem. A, 2022, 10: 6454-6462.

[226] Zhang LC, Zhou Q, Liang J, et al. . Enhancing electrocatalytic NO reduction to NH₃ by the CoS nanosheet with sulfur vacancies. Inorg. Chem., 2022, 61: 8096-8102.

[227] Liang J, Hu WF, Song BY, et al. . Efficient nitric oxide electroreduction toward ambient ammonia synthesis catalyzed by a CoP nanoarray. Inorg. Chem. Front., 2022, 9: 1366-1372.

[228] Lin YT, Liang J, Li HB, et al. . Bi nanodendrites for highly efficient electrocatalytic NO reduction to NH₃ at ambient conditions. Mater. Today Phys., 2022, 22100611

[229] Liang J, Liu PY, Li QY, et al. . Amorphous boron carbide on titanium dioxide nanobelt arrays for high-efficiency electrocatalytic NO reduction to NH₃. Angew. Chem. Int. Ed., 2022, 61e202202087

[230] Liu Q, Lin YT, Yue LC, et al. . Bi nanoparticles/carbon nanosheet composite: a high-efficiency electrocatalyst for NO reduction to NH₃. Nano Res., 2022, 15: 5032-5037.

[231] Li ZX, Zhou Q, Liang J, et al. . Defective TiO₂−xfor high-performance electrocatalytic NO reduction toward ambient NH₃production. Small, 2023, 192300291

[232] Wang DD, Zhu XR, Tu XJ, et al. . Oxygen-bridged copper–iron atomic pair as dual-metal active sites for boosting electrocatalytic NO reduction. Adv. Mater., 2023, 352304646

[233] Wang DD, Chen ZW, Gu KZ, et al. . Hexagonal cobalt nanosheets for high-performance electrocatalytic NO reduction to NH₃. J. Am. Chem. Soc., 2023, 145: 6899-6904.

[234] Zhang X, Wang YT, Wang YB, et al. . Recent advances in electrocatalytic nitrite reduction. Chem. Commun., 2022, 58: 2777-2787.

[235] Yue LC, Song W, Zhang LX, et al. . Recent advance in heterogenous electrocatalysts for highly selective nitrite reduction to ammonia under ambient condition. Small Struct., 2023, 42300168

[236] Wang JQ, Liang J, Liu PY, et al. . Biomass Juncus derived carbon decorated with cobalt nanoparticles enables high-efficiency ammonia electrosynthesis by nitrite reduction. J. Mater. Chem. A, 2022, 10: 2842-2848.

[237] Li SX, Liang J, Wei PP, et al. . ITO@TiO₂ nanoarray: an efficient and robust nitrite reduction reaction electrocatalyst toward NH₃ production under ambient conditions. eScience, 2022, 2: 382-388.

[238] Zhang R, Zhang SC, Guo Y, et al. . A Zn-nitrite battery as an energy-output electrocatalytic system for high-efficiency ammonia synthesis using carbon-doped cobalt oxide nanotubes. Energy Environ. Sci., 2022, 15: 3024-3032.

[239] Ma LT, Chen SM, Yan WH, et al. . A high-energy aqueous Zn‖NO₂ electrochemical cell: a new strategy for NO₂ fixation and electric power generation. Energy Environ. Sci., 2023, 16: 1125-1134.

[240] Bi ZH, Hu J, Xu M, et al. . Nitrogen-bridged Fe–Cu atomic pair sites for efficient electrochemical ammonia production and electricity generation with Zn–NO₂ batteries. Angew. Chem., 2024, 136e202313434

[241] Li J, Zhan GM, Yang JH, et al. . Efficient ammonia electrosynthesis from nitrate on strained ruthenium nanoclusters. J. Am. Chem. Soc., 2020, 142: 7036-7046.

[242] Guo Y, Zhang R, Zhang SC, et al. . Pd doping-weakened intermediate adsorption to promote electrocatalytic nitrate reduction on TiO₂ nanoarrays for ammonia production and energy supply with zinc-nitrate batteries. Energy Environ. Sci., 2021, 14: 3938-3944.

[243] Zhang R, Guo Y, Zhang SC, et al. . Efficient ammonia electrosynthesis and energy conversion through a Zn-nitrate battery by iron doping engineered nickel phosphide catalyst. Adv. Energy Mater., 2022, 122103872

[244] Lin W, Zhou EB, Xie JF, et al. . A high power density Zn-nitrate electrochemical cell based on theoretically screened catalysts. Adv. Funct. Mater., 2022, 322209464

[245] Li ZR, Liang J, Liu Q, et al. . High-efficiency ammonia electrosynthesis via selective reduction of nitrate on ZnCo₂O₄ nanosheet array. Mater. Today Phys., 2022, 23100619

[246] Liu Q, Xie LS, Liang J, et al. . Ambient ammonia synthesis via electrochemical reduction of nitrate enabled by NiCo₂O₄ nanowire array. Small, 2022, 182106961

[247] Ma JH, Zhang YT, Wang BW, et al. . Interfacial engineering of bimetallic Ni/co-MOFs with H-substituted graphdiyne for ammonia electrosynthesis from nitrate. ACS Nano, 2023, 17: 6687-6697.

[248] Gao YH, Wang KP, Xu C, et al. . Enhanced electrocatalytic nitrate reduction through phosphorus-vacancy-mediated kinetics in heterogeneous bimetallic phosphide hollow nanotube array. Appl. Catal. B-Environ., 2023, 330122627

[249] Ding JY, Hou XH, Qiu Y, et al. . Iron-doping strategy promotes electroreduction of nitrate to ammonia on MoS₂ nanosheets. Inorg. Chem. Commun., 2023, 151110621

[250] Zhou FL, Sun CH. Nitrate-to-ammonia conversion on Ru/Ni hydroxide hybrid through zinc-nitrate fuel cell. Small, 2022, 182200436

[251] Jiang HF, Chen GF, Savateev O, et al. . Enabled efficient ammonia synthesis and energy supply in a zinc–nitrate battery system by separating nitrate reduction process into two stages. Angew. Chem. Int. Ed., 2023, 62e202218717

[252] Zhu WJ, Yao F, Wu QF, et al. . Weakened d–p orbital hybridization in in situ reconstructed Ru/β-Co(OH)₂heterointerfaces for accelerated ammonia electrosynthesis from nitrates. Energy Environ. Sci., 2023, 16: 2483-2493.

[253] Zhang R, Li C, Cui HL, et al. . Electrochemical nitrate reduction in acid enables high-efficiency ammonia synthesis and high-voltage pollutes-based fuel cells. Nat. Commun., 2023, 148036

[254] Zhou JW, Xiong YC, Sun MZ, et al. . Constructing molecule-metal relay catalysis over heterophase metallene for high-performance rechargeable zinc-nitrate/ethanol batteries. Proc. Natl. Acad. Sci. U.S.A., 2023, 120e2311149120

[255] Ran Y, Xu CF, Ji DY, et al. . Research progress of transition metal compounds as bifunctional catalysts for zinc-air batteries. Nano Res. Energy, 2024, 3e9120092

[256] Ran Y, Dong F, Sun SH, et al. . Aqueous zinc-based batteries: active materials, device design, and future perspectives. Adv. Energy Mater., 2025

[257] Na J, Seo B, Kim J, et al. . General technoeconomic analysis for electrochemical coproduction coupling carbon dioxide reduction with organic oxidation. Nat. Commun., 2019, 105193

[258] Xia Q, Jin CK, Huang YL, et al. . Methanol-facilitated surface reconstruction catalysts for near 200% faradaic efficiency in a coupled system. Adv. Funct. Mater., 2024, 342314596

[259] Valentini F, Marrocchi A, Vaccaro L. Liquid organic hydrogen carriers (LOHCs) as H-source for bio-derived fuels and additives production. Adv. Energy Mater., 2022, 122103362

[260] Zhu P, Wang HT. High-purity and high-concentration liquid fuels through CO₂ electroreduction. Nat. Catal., 2021, 4: 943-951.

[261] Li JZ, Li H, Fan K, et al. . Electrocatalytic nitrate reduction to ammonia coupled with organic oxidation. Chem. Catal., 2023, 3100638

[262] Chang, B., Pang, H., Raziq, F., et al.: Electrochemical reduction of carbon dioxide to multicarbon (C₂₊) products: challenges and perspectives. Energy Environ. Sci. 16, 4714–4758 (2023). https://doi.org/10.1039/D3EE00964E

Funding

Deutsche Forschungsgemeinschaft(501766751)

Chinesisch-Deutsche Zentrum für Wissenschaftsförderung(GZ1579)

Technische Universität Ilmenau (3141)

RIGHTS & PERMISSIONS

The Author(s)