Engineering oxygen-vacancy-rich NiO/CuO composites for efficient photoelectrocatalytic methanol oxidation

Abstract

With the continuous advancement of the new energy sector, direct methanol fuel cells (DMFCs) have attracted significant research interest. However, the development of DMFCs is hindered by the reliance on platinum-based anode catalysts, which suffer from high cost, intermediate-induced poisoning, and rapid performance degradation. Herein, this study develops a low-cost NiO/CuO composite for efficient methanol oxidation reaction (MOR) through defect engineering and heterojunction strategy. The NiO/CuO composite exhibits higher concentration of oxygen vacancies and interface lattice distortion compared to their individual counterparts. The NiO/CuO composite exhibits exceptional photoelectrochemical MOR activity and stability. The enhanced performance is attributed to the synergistic effect of the NiO/CuO heterojunction and the high concentration of oxygen vacancies, which together improve light absorption, increase the electrochemically active surface area, provide more active sites, and accelerate charge transfer kinetics. This work presents a promising strategy for designing cost-effective, high-performance photo-assisted anode catalysts for DMFCs.

Graphical abstract

Keywords

photoelectrocatalysis / methanol oxidation reaction / nickel oxide / copper oxide / direct methanol fuel cells

References

[1] Din M A U, Idrees M, Jamil S, et al. Advances and challenges of methanol-tolerant oxygen reduction reaction electrocatalysts for the direct methanol fuel cell.Journal of Energy Chemistry, 2023, 77: 499–513

[2] Wang J, Zhang B, Guo W, et al. Toward electrocatalytic methanol oxidation reaction: longstanding debates and emerging catalysts.Advanced Materials, 2023, 35(26): 2211099

[3] Li J, Yang F, Feng L . Progress of supported Pt-based catalysts for electrochemical methanol energy conversion.Coordination Chemistry Reviews, 2025, 534: 216603

[4] Wan Z, Wan X, Ye J, et al. Tuning d-band center of Pt via Pt–Pt₅La heterostructure interface as efficient and stable electrocatalyst for oxygen reduction and methanol oxidation reactions in DMFCs.Chemical Engineering Journal, 2024, 498: 155564

[5] Li J, Zhou Z, Xu H, et al. In situ nanopores enrichment of mesh-like palladium nanoplates for bifunctional fuel cell reactions: a joint etching strategy.Journal of Colloid and Interface Science, 2022, 611: 523–532

[6] Yuda A, Ashok A, Kumar A . A comprehensive and critical review on recent progress in anode catalyst for methanol oxidation reaction.Catalysis Reviews: Science and Engineering, 2022, 64(1): 126–228

[7] Phan V T T, Nguyen Q P, Wang B, et al. Oxygen vacancies alter methanol oxidation pathways on NiOOH.Journal of the American Chemical Society, 2024, 146(7): 4830–4841

[8] Jasim A M, Xu G, Young M J, et al. Tuning vacancy in metal oxide support to enhance activity and durability of Pt catalysts for the methanol oxidation reaction.ACS Catalysis, 2025, 15(5): 4350–4358

[9] Cao S, Li M, Guo Z, et al. Crystal-phase-controlled PtSn intermetallic nanowires for efficient methanol oxidation.Science China: Chemistry, 2024, 67(12): 4142–4148

[10] Luo S, Xie L, Cai X, et al. Golden single-atom alloys selectively boosting oxygen reduction and methanol oxidation.Advanced Materials, 2025, 37(28): 2500848

[11] Çelik S, Yagız M, Atalmis G . Experimental improvement of the performance of the open cathode-direct methanol fuel cell stack by magnetic field effect.International Journal of Hydrogen Energy, 2024, 50: 32–40

[12] Antolini E . Photo-assisted methanol oxidation on Pt–TiO₂ catalysts for direct methanol fuel cells: a short review.Applied Catalysis B: Environmental, 2018, 237: 491–503

[13] Kwok Y H, Wang Y, Zhang Y, et al. Boosting cell performance and fuel utilization efficiency in a solar assisted methanol microfluidic fuel cell.International Journal of Hydrogen Energy, 2020, 45(41): 21796–21807

[14] Zhao Q, Hong H, Zhong Q, et al. Revealing the multiple function of nitrogen-doped carbon layer in hematite-based photoanode for photoelectrochemical water oxidation.Advanced Functional Materials, 2025, 35(27): 2424885

[15] Alyousef Z, Crisalle O D . Dual-threshold control architecture for improved thermal and power management in open-cathode direct methanol fuel cell.Energy Conversion and Management: X, 2024, 23: 100621

[16] Shi J, Wang B, Hu S . From photo-assisted methanol catalytic oxidation to direct methanol fuel cells: applications of semiconductors-based electrode.Surfaces and Interfaces, 2024, 46: 103970

[17] Wang P C, Zheng W, Qu Y F, et al. Photo-excited high-spin state Ni(III) species in Mo-doped Ni₃S₂ for efficient urea oxidation reaction.Small, 2024, 20(45): 2403107

[18] Xie D, Hu S, Teng D, et al. Non-noble Si NWs@ZnO core–shell heterojunction anode enables a photo-assisted mirco direct methanol fuel cell.Chemical Engineering Journal, 2023, 457: 141310

[19] Vij V, Sultan S, Harzandi A M, et al. Nickel-based electrocatalysts for energy-related applications: oxygen reduction, oxygen evolution, and hydrogen evolution reactions.ACS Catalysis, 2017, 7(10): 7196–7225

[20] Jia F, Zhang Y, Ma X, et al. Electric field derived from NiCo₂S₄–MoS₂ n–n heterojunction promoted electrocatalytic methanol oxidation assisted energy-saving hydrogen production.Journal of Colloid and Interface Science, 2025, 693: 137650

[21] Wang F, Wu L S, Qian L, et al. Noble metal-free CoS_x/NiS_x heterojunction for photo-assisted methanol electrooxidation.ChemElectroChem, 2022, 9(19): e202200909

[22] Li J, Li L, Wang J, et al. Boosting hydrogen evolution by methanol oxidation reaction on Ni-based electrocatalysts: from fundamental electrochemistry to perspectives.ACS Energy Letters, 2024, 9(3): 853–879

[23] Wang K, Sun T, Ma H, et al. Energy band modulating of NiO/BiOCl heterojunction with transition from type-II to S-scheme for enhancing photocatalytic CO₂ reduction.Chemical Engineering Journal, 2024, 497: 154711

[24] Li M Y, Li H M, Xiang K, et al. Oxygen vacancy in accelerating the electrocatalytic small molecule oxidation properties.Electrochemical Energy Reviews, 2025, 8(1): 4

[25] Li W X, Liu M J, Wu X Y, et al. Membrane-less electrocatalytic ammonia synthesis coupled with selective methanol oxidation via porous Ni²⁺-doped Co₃O₄ nanosheets.Chemical Engineering Journal, 2024, 500: 157284

[26] Zhang Y H, Zhang S, Hu N, et al. Oxygen vacancy chemistry in oxide cathodes.Chemical Society Reviews, 2024, 53(7): 3302–3326

[27] Pieta I S, Rathi A, Pieta P, et al. Electrocatalytic methanol oxidation over Cu, Ni and bimetallic Cu–Ni nanoparticles supported on graphitic carbon nitride.Applied Catalysis B: Environmental, 2019, 244: 272–283

[28] Sun Z, Li C, Wei Z, et al. Sulfur-bridged asymmetric CuNi bimetallic atom sites for CO₂ reduction with high efficiency.Advanced Materials, 2024, 36(33): 2404665

[29] Kotp A A, Abdelwahab A, Farghali A A, et al. Facile synthesis of green graphite-based (Ni/Cu/N) MOF composite for a methanol oxidation reaction.International Journal of Hydrogen Energy, 2024, 91: 506–518

[30] Alotaibi A M, Muayqil E, Al Abass N, et al. Surface engineering of CuO–Cu₂O heterojunction thin films for improved photoelectrochemical water splitting.Renewable Energy, 2024, 235: 121326

[31] He B, Jiang S, Wang C, et al. Synergy between copper and cobalt on 3D Co/CuO complex promotes peroxymonosulfate activation.Chemical Engineering Journal, 2024, 480: 148025

[32] Maheskumar V, Min A, Moon C J, et al. Modulating the electronic structure of Ni/NiO nanocomposite with high-valence Mo doping for energy-saving hydrogen production via boosting urea oxidation kinetics.Small Structures, 2023, 4(12): 2300212

[33] Zhao L, Zhang J, Zhang Z, et al. CuO with (001)-plane exposure efficiently induces peroxymonosulfate to form =Cu−OOSO₃⁻ intermediates directly oxidizing organic contaminants in water.Chemical Engineering Journal, 2022, 441: 136100

[34] Li Y, Zhou W, Duan X, et al. Sea urchin-like Pr-doped W₁₈O₄₉ nanospheres for high-performance supercapacitors.Journal of Energy Storage, 2024, 104: 114560

[35] Gao W, Xia Z, Cao F, et al. Comprehensive understanding of the spatial configurations of CeO₂ in NiO for the electrocatalytic oxygen evolution reaction: embedded or surface-loaded.Advanced Functional Materials, 2018, 28(11): 1706056

[36] Zhao J, Shen Z, Yu J, et al. Constructing Cu–CuO heterostructured skin on Cu cubes to promote electrocatalytic ammonia production from nitrate wastewater.Journal of Hazardous Materials, 2022, 439: 129653

[37] Li D, Wei G, Xing Z, et al. Sulfate anchored on the defective NiO by ion irradiation realizes enhanced oxygen evolution reaction.Chemical Engineering Journal, 2024, 485: 149890

[38] Cerrón-Calle G A, Fajardo A S, Sánchez-Sánchez C M, et al. Highly reactive Cu–Pt bimetallic 3D-electrocatalyst for selective nitrate reduction to ammonia.Applied Catalysis B: Environmental, 2022, 302: 120844

[39] Zhang Y, Jiang H, Zhang C, et al. High-efficiency oxygen reduction by late transition metal oxides to produce H₂O₂.Journal of Materials Chemistry A: Materials for Energy and Sustainability, 2024, 12(10): 6123–6133

[40] Yu Y, Pan M, Zhang Z, et al. Improved electrocatalytic methanol oxidation of NiO nanosheet arrays with synergistic high surface oxygen vacancy and Ni³⁺/Ni²⁺ ratio.International Journal of Hydrogen Energy, 2023, 48(71): 27679–27685

[41] Lee H J, Back S, Lee J H, et al. Mixed transition metal oxide with vacancy-induced lattice distortion for enhanced catalytic activity of oxygen evolution reaction.ACS Catalysis, 2019, 9(8): 7099–7108

[42] Wang H, He Q F, Gao X, et al. Multifunctional high entropy alloys enabled by severe lattice distortion.Advanced Materials, 2024, 36(17): 2305453

[43] Li S L, Ma R G, Hu J C, et al. Coordination environment tuning of nickel sites by oxyanions to optimize methanol electro-oxidation activity.Nature Communications, 2022, 13(1): 2916

[44] Huang W J, Wang H T, Zhou J G, et al. Highly active and durable methanol oxidation electrocatalyst based on the synergy of platinum–nickel hydroxide–graphene.Nature Communications, 2015, 6(1): 10035

[45] Lu W H, Du T T, Jia S J, et al. Efficient photogenerated carrier-assisted CO_ads removal via Schottky barrier of PdSn/WO₃ for formic acid oxidation reaction.Small, 2025, 21(23): 2501505

[46] Lv T, Yang L, Hong C, et al. Electronic interaction at Cu–O–Ni heterointerface promotes electrocatalytic nitrate reduction to ammonia and zinc–nitrate battery.Advanced Science, 2026, 13(14): e21252

[47] Qin X, Sultana F, Li T, et al. Boosting synergistic methanol oxidation and hydrogen evolution via MnO₂-decorated Ni₃Se₂/NF heterojunction catalysts for low-voltage water splitting.ACS Applied Energy Materials, 2025, 8(8): 5153–5165

[48] Feng Y, Wu J, Chi Q, et al. Defects and aliovalent doping engineering in electroceramics.Chemical Reviews, 2020, 120(3): 1710–1787

[49] Yang W, Yang X, Jia J, et al. Oxygen vacancies confined in ultrathin nickel oxide nanosheets for enhanced electrocatalytic methanol oxidation.Applied Catalysis B: Environmental, 2019, 244: 1096–1102

RIGHTS & PERMISSIONS

Higher Education Press