Methanol-Assisted Hybrid Electrolysis for Green Hydrogen and Formate Production Using a Trifunctional Cu–Co–Mo Oxide Catalyst

Tackling the global energy crisis and environmental pollution driven by rising fossil fuel consumption requires the development of renewable, green, and continuous energy sources. Hydrogen (H 2 ) production via renewable energy-powered water electrolysis offers a sustainable solution, where development of efficient, cost-effective electrocatalysts is critical. This article reports nickel foam (NF)-supported relatively unexplored trimetallic Cu–Co–Mo oxide (CuCoMo-O/NF) costing $0.051 cm –2, as a trifunctional electrocatalyst for the methanol oxidation reaction (MOR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER). The CuCoMo-O/NF catalyst demonstrates superior electrocatalytic activity compared to its monometallic and bimetallic counterparts (Co 3 O 4 /NF, CoMo-O/NF, and CuCo-O/NF). CuCoMo-O/NF exhibits 244 mV (OER) and 234 mV (HER) overpotential at 50 mA cm –2, where MOR required a 74 mV lower potential than the OER. The fabricated conventional CuCoMo-O/NF(±) electrolyzer operates at 1.803 V to deliver 100 mA cm –2, significantly reduced to 1.623 V in the MOR-integrated hybrid electrolyzer, which simultaneously valorizes methanol to formate ions in a greener way while boosting H 2 production. Both electrolyzers display remarkable long-term stability over 100 h. The Faradaic efficiency (FE) of the electrolyzers is ∼99.4%, with an electricity cost for H 2 production of $1.25 kg –1 for the conventional electrolyzer, which has been further reduced to $0.95 kg –1 using the hybrid CuCoMo-O/NF(±) electrolyzer, meeting the U.S. Department of Energy target (