Accelerating Electrocatalytic Nitrate Reduction to Ammonia via Weakening of Intermediate Adsorption on Cu-Based Catalyst

Abstract

Cu-based materials are commonly used in electrocatalytic nitrate reduction reactions (NO₃RR). NO₃RR is a “two birds, one stone” approach, simultaneously removing NO₃ ⁻ pollutants and producing valuable ammonia (NH₃). However, the strong coordination between the NO₃ ⁻ intermediate and the catalytic active sites seriously hinders the conversion efficiency. Here, we determined that, through encapsulation strategies, the carbon layer could weaken the NO₃ ⁻ intermediate binding to active sites, resulting in higher NH₃ yields. We experimentally fabricated electrocatalysts, i.e., Cu nanoparticles encapsulating (or loaded on) N-doped carbon nanofibers (NCNFs) called Cu@NCNFs (Cu-NCNFs), using electrostatic spinning. As a result, Cu@NCNFs can achieve NH₃ yields of 17.08 mg/(h·mg_cat) at a voltage of − 0.84 V and a Faraday efficiency of 98.15%. Meanwhile, the electrochemical properties of the Cu nanoparticles on the surface of carbon fibers (Cu-NCNFs) are lower than those of the Cu@NCNFs. The in situ Raman spectra of Cu@NCNFs and Cu-NCNFs under various reduction potentials during the NO₃RR process show that catalyst encapsulation within carbon layers can effectively reduce the adsorption of N species by the catalyst, thus improving the catalytic performance in the nitrate-to-ammonia catalytic conversion process.

Keywords

Electrocatalytic nitrate reduction reactions / Ammonia synthesis / Copper-based electrocatalysts / Electrostatically spun carbon fiber / Regulated adsorption

References

[1] Jiang Z, Wang Y, Lin Z, et al. Molecular electrocatalysts for rapid and selective reduction of nitrogenous waste to ammonia. Energy Environ Sci, 2023, 16(5): 2239-2246

[2] Zhang X, Ward BB, Sigman DM. Global nitrogen cycle: critical enzymes, organisms, and processes for nitrogen budgets and dynamics. Chem Rev, 2020, 120(12): 5308-5351

[3] Gao W, Perales-Rondon JV, Michalička J, et al. Ultrathin manganese oxides enhance the electrocatalytic properties of 3D printed carbon catalysts for electrochemical nitrate reduction to ammonia. Appl Catal B Environ, 2023, 330

[4] Li T, Han S, Wang C, et al. Ru-doped Pd nanoparticles for nitrogen electrooxidation to nitrate. ACS Catal, 2021, 11(22): 14032-14037

[5] Bui TS, Lovell EC, Daiyan R, et al. Defective metal oxides: lessons from CO₂RR and applications in NO _xRR. Adv Mater, 2023, 35(28): 2205814

[6] Choi J, Du HL, Nguyen CK, et al. Electroreduction of nitrates, nitrites, and gaseous nitrogen oxides: a potential source of ammonia in dinitrogen reduction studies. ACS Energy Lett, 2020, 5(6): 2095-2097

[7] Xiong Y, Wang Y, Zhou J, et al. Electrochemical nitrate reduction: ammonia synthesis and the beyond. Adv Mater, 2024, 36(17):

[8] Guo Y, Zhang S, Zhang R, et al. Electrochemical nitrate production via nitrogen oxidation with atomically dispersed Fe on N-doped carbon nanosheets. ACS Nano, 2022, 16(1): 655-663

[9] Chen FY, Wu ZY, Gupta S, et al. Efficient conversion of low-concentration nitrate sources into ammonia on a Ru-dispersed Cu nanowire electrocatalyst. Nat Nanotechnol, 2022, 17(7): 759-767

[10] Xie M, Tang S, Li Z, et al. Intermetallic single-atom alloy In-Pd bimetallene for neutral electrosynthesis of ammonia from nitrate. J Am Chem Soc, 2023, 145(25): 13957-13967

[11] Deng Z, Ma C, Li Z, et al. High-efficiency electrochemical nitrate reduction to ammonia on a Co₃O₄ nanoarray catalyst with cobalt vacancies. ACS Appl Mater Interfaces, 2022, 14(41): 46595-46602

[12] Gao Z, Lai Y, Tao Y, et al. Constructing well-defined and robust Th-MOF-supported single-site copper for production and storage of ammonia from electroreduction of nitrate. ACS Cent Sci, 2021, 7(6): 1066-1072

[13] Fan X, Zhao D, Deng Z, et al. Constructing Co@TiO₂ nanoarray heterostructure with Schottky contact for selective electrocatalytic nitrate reduction to ammonia. Small, 2023, 19(17):

[14] Fan X, Ma C, Zhao D, et al. Unveiling selective nitrate reduction to ammonia with Co₃O₄ nanosheets/TiO₂ nanobelt heterostructure catalyst. J Colloid Interface Sci, 2023, 630(Pt A): 714-720

[15] Chen J, He X, Li J, et al. Three-dimensional porous Co foam with nanosheets subunits for high-performance electrocatalytic nitrate-to-ammonia conversion. Inorg Chem Front, 2023, 10(15): 4450-4455

[16] Zhu E, Zhao Y, Dai Y, et al. Heterojunction-type photocatalytic system based on inorganic halide perovskite CsPbBr3. Chin J Chem, 2020, 38(12): 1718-1722

[17] Wu H, Li A, Yang X, et al. The research progress, hotspots, challenges and outlooks of solid-phase denitrification process. Sci Total Environ, 2023, 858(Pt 3):

[18] Thomazo C, Couradeau E, Garcia-Pichel F. Possible nitrogen fertilization of the early Earth Ocean by microbial continental ecosystems. Nat Commun, 2018, 9(1): 2530

[19] Zhao Z, Chen C, Liu Z, et al. Pt-based nanocrystal for electrocatalytic oxygen reduction. Adv Mater, 2019, 31(31):

[20] Wang H, Gao J, Chen C, et al. PtNi-W/C with atomically dispersed tungsten sites toward boosted ORR in proton exchange membrane fuel cell devices. Nanomicro Lett, 2023, 15(1): 143

[21] Chen C, Sun M, Zhang F, et al. Adjacent Fe Site boosts electrocatalytic oxygen evolution at Co site in single-atom-catalyst through a dual-metal-site design. Energy Environ Sci, 2023, 16(4): 1685-1696

[22] Sun Z, Wang G, Koh SW, et al. Solar-driven alkaline water electrolysis with multifunctional catalysts. Adv Funct Materials, 2020, 30(27): 2002138

[23] Sun Z, Sun L, Koh SW, et al. Photovoltaic-powered supercapacitors for driving overall water splitting: a dual-modulated 3D architecture. Carbon Energy, 2022, 4(6): 1262-1273

[24] MacFarlane DR, Cherepanov PV, Choi J, et al. A roadmap to the ammonia economy. Joule, 2020, 4(6): 1186-1205

[25] Du F, Li J, Wang C, et al. Active sites-rich layered double hydroxide for nitrate-to-ammonia production with high selectivity and stability. Chem Eng J, 2022, 434

[26] Garcia-Segura S, Lanzarini-Lopes M, Hristovski K, et al. Electrocatalytic reduction of nitrate: fundamentals to full-scale water treatment applications. Appl Catal B Environ, 2018, 236: 546-568

[27] Ouyang L, Liang J, Luo Y, et al. Recent advances in electrocatalytic ammonia synthesis. Chin J Catal, 2023, 50: 6-44

[28] Zhou J, Wen M, Huang R, et al. Regulating active hydrogen adsorbed on grain boundary defects of nano-nickel for boosting ammonia electrosynthesis from nitrate. Energy Environ Sci, 2023, 16(6): 2611-2620

[29] Hu X, Sun Z, Mei G, et al. Engineering nonprecious metal oxides electrocatalysts for two-electron water oxidation to H₂O₂. Adv Energy Mater, 2022, 12(32): 2201466

[30] Wei C, Heng N, Wang Z, et al. Dynamic active site evolution and stabilization of core-shell structure electrode for oxygen evolution reaction. Chem Eng J, 2022, 435

[31] Sun B, Sun Z, Yang Y, et al. Covalent organic frameworks: their composites and derivatives for rechargeable metal-ion batteries. ACS Nano, 2024, 18(1): 28-66

[32] Wang Y, Dutta A, Iarchuk A, et al. Boosting nitrate to ammonia electroconversion through hydrogen gas evolution over Cu-foam@mesh catalysts. ACS Catal, 2023, 13(12): 8169-8182

[33] Wang C, Liu Z, Dong L, et al. Bimetallic CuCo nanocrystals to tailor absorption energy of intermediators for efficient electrochemical nitrate conversion to ammonia in neutral electrolyte. J Power Sources, 2023, 556

[34] Hu T, Wang C, Wang M, et al. Theoretical insights into superior nitrate reduction to ammonia performance of copper catalysts. ACS Catal, 2021, 11(23): 14417-14427

[35] Fajardo AS, Westerhoff P, Sanchez-Sanchez CM, et al. Earth-abundant elements a sustainable solution for electrocatalytic reduction of nitrate. Appl Catal B Environ, 2021, 281

[36] Zeng Y, Priest C, Wang G, et al. Restoring the nitrogen cycle by electrochemical reduction of nitrate: progress and prospects. Small Meth, 2020, 4(12): 2000672

[37] Chen GF, Yuan Y, Jiang H, et al. Electrochemical reduction of nitrate to ammonia via direct eight-electron transfer using a copper–molecular solid catalyst. Nat Energy, 2020, 5: 605-613

[38] Zhang X, Wang Y, Liu C, et al. Recent advances in non-noble metal electrocatalysts for nitrate reduction. Chem Eng J, 2021, 403

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

[40] Duca M, Sacré N, Wang A, et al. Enhanced electrocatalytic nitrate reduction by preferentially-oriented (100) PtRh and PtIr alloys: the hidden treasures of the ‘miscibility gap’. Appl Catal B Environ, 2018, 221: 86-96

[41] Liang J, Li Z, Zhang L, et al. Advances in ammonia electrosynthesis from ambient nitrate/nitrite reduction. Chem, 2023, 9(7): 1768-1827

[42] Song W, Yue L, Fan X, et al. Recent progress and strategies on the design of catalysts for electrochemical ammonia synthesis from nitrate reduction. Inorg Chem Front, 2023, 10(12): 3489-3514

[43] Liu X, Liu C, He X, et al. Fe-doped Co₃O₄ nanowire strutted 3D pinewood-derived carbon: a highly selective electrocatalyst for ammonia production via nitrate reduction. Nano Res, 2024, 17(4): 2276-2282

[44] Yoshioka T, Iwase K, Nakanishi S, et al. Electrocatalytic reduction of nitrate to nitrous oxide by a copper-modified covalent triazine framework. J Phys Chem C, 2016, 120(29): 15729-15734

[45] Yoo JM, Shin H, Chung DY, et al. Carbon shell on active nanocatalyst for stable electrocatalysis. Acc Chem Res, 2022, 55(9): 1278-1289

[46] Liu G, Li X, Ganesan P, et al. Development of non-precious metal oxygen-reduction catalysts for PEM fuel cells based on N-doped ordered porous carbon. Appl Catal B Environ, 2009, 93(1–2): 156-165

[47] Liu Y, Pan C, Wang J. Raman spectra of carbon nanotubes and nanofibers prepared by ethanol flames. J Mater Sci, 2004, 39(3): 1091-1094

[48] Wang X, Vasileff A, Jiao Y, et al. Electronic and structural engineering of carbon-based metal-free electrocatalysts for water splitting. Adv Mater, 2019, 31(13):

[49] Xu L, Yang Y, Hu ZW, et al. Comparison study on the stability of copper nanowires and their oxidation kinetics in gas and liquid. ACS Nano, 2016, 10(3): 3823-3834

[50] Jung J, Bae S, Lee W. Nitrate reduction by maghemite supported Cu-Pd bimetallic catalyst. Appl Catal B Environ, 2012, 127: 148-158

[51] Pels JR, Kapteijn F, Moulijn JA, et al. Evolution of nitrogen functionalities in carbonaceous materials during pyrolysis. Carbon, 1995, 33(11): 1641-1653

[52] Zhang G, Zhu J, Zeng W, et al. Tin quantum dots embedded in nitrogen-doped carbon nanofibers as excellent anode for lithium-ion batteries. Nano Energy, 2014, 9: 61-70

[53] Li Y, Zhang H, Chen Y, et al. Nitrogen-doped carbon-encapsulated SnO₂@Sn nanoparticles uniformly grafted on three-dimensional graphene-like networks as anode for high-performance lithium-ion batteries. ACS Appl Mater Interfaces, 2016, 8(1): 197-207

[54] Sengupta R, Bhattacharya M, Bandyopadhyay S, et al. A review on the mechanical and electrical properties of graphite and modified graphite reinforced polymer composites. Prog Polym Sci, 2011, 36(5): 638-670

[55] 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

[56] Zhang T, Zong W, Ouyang Y, et al. Carbon fiber supported binary metal sulfide catalysts with multi-dimensional structures for electrocatalytic nitrogen reduction reactions over a wide pH range. Adv Fiber Mater, 2021, 3(4): 229-238

[57] Zhang Y, Liu S, Yan J, et al. Superior flexibility in oxide ceramic crystal nanofibers. Adv Mater, 2021, 33(44):

[58] Karbownik I, Fiedot M, Rac O, et al. Effect of doping polyacrylonitrile fibers on their structural and mechanical properties. Polymer, 2015, 75: 97-108

[59] Zhang L, Luo J, Menkhaus TJ, et al. Antimicrobial nano-fibrous membranes developed from electrospun polyacrylonitrile nanofibers. J Membr Sci, 2011, 369(1–2): 499-505

[60] Ouyang Q, Wang X, Wang X, et al. Simultaneous DSC/TG analysis on the thermal behavior of PAN polymers prepared by aqueous free-radical polymerization. Polym Degrad Stab, 2016, 130: 320-327

[61] Li Z, Zhang L, Yang C, et al. Graphitized carbon nanocages/palladium nanoparticles: sustainable preparation and electrocatalytic performances towards ethanol oxidation reaction. Int J Hydrog Energy, 2019, 44(12): 6172-6181

[62] Taguchi S, Feliu JM. Kinetic study of nitrate reduction on Pt (1 1 0) electrode in perchloric acid solution. Electrochim Acta, 2008, 53(10): 3626-3634

[63] He W, Zhang J, Dieckhöfer S, et al. Splicing the active phases of copper/cobalt-based catalysts achieves high-rate tandem electroreduction of nitrate to ammonia. Nat Commun, 2022, 13(1): 1129

[64] Niu Z, Fan S, Li X, et al. Interfacial engineering of CoMn₂O₄/NC induced electronic delocalization boosts electrocatalytic nitrogen oxyanions reduction to ammonia. Appl Catal B Environ, 2023, 322