A revolutionizing multifunctional CoMoO4/MnMoO4 oxide with highly selective methanol oxidation for boosting hydrogen evolution

Abstract

This study presents the development of a high-performance bimetallic CoMoO4/MnMoO4 oxide-based electrocatalyst designed to revolutionize hydrogen production through highly selective methanol oxidation. A dropcasted, binder-free oxide film on a nickel foam substrate demonstrated exceptional electrocatalytic activity for the methanol oxidation reaction (MOR), significantly outperforming its individual oxide counterparts and their physical mixture. In an alkaline electrolyte, the CoMoO4/MnMoO4 film exhibited remarkably low MOR potentials of 1.26 and 1.40 V vs. reversible hydrogen electrode (RHE) at current densities of 10 and 100 mA cm-2, respectively, compared to 1.56 and 1.68 V vs. RHE for the conventional oxygen evolution reaction (OER). Furthermore, the designed oxide electrode-based electrolyzer enabled the methanol oxidation toward a high selectivity of formate formation with an approximately 100 % faradaic efficiency for hydrogen evolution at 100 mA cm-2. Operating the electrolyzer at 1.56 V and replacing the OER at the anode with MOR, the electricity consumption for hydrogen production was reduced from 4.57 kWh.m-3 to 3.73 kWh.m-3. Under this condition, a 20-fold increase in H2 production was achieved and the cost of the electricity was lowered by 840 Watts perhour. Additionally, the CoMoO4/MnMoO4 film demonstrated superior stability under MOR conditions, making it a promising candidate for sustainable and cost-effective hydrogen production.