Bifunctional Pt–Co3O4 electrocatalysts for simultaneous generation of hydrogen and formate via energy-saving alkaline seawater/methanol co-electrolysis

Abstract

Electrocatalytic seawater splitting has been considered as a transformative technology for industrial-scale hydrogen generation. However, the competition between the oxygen evolution reaction (OER) and chlorine evolution reaction (CER) at the anode with sluggish kinetics is the main bottleneck. Herein, an organic-oxidation-assisted strategy has been demonstrated, in which the thermodynamically favorable methanol selective oxidation reaction (MSOR) is used to suppress the undesired OER/CER using carbon paper supported Pt–Co₃O₄ electrocatalysts (denoted as Pt–Co₃O₄/CP), leading to hydrogen and value-added formate generation simultaneously with significantly low energy consumption. In the integrated two-electrode electrolyzer using Pt–Co₃O₄/CP bifunctional electrocatalysts, the required cell voltage at 10 mA cm⁻² is only 0.555 V when adding 2.0 M methanol, which is 1022 mV lower than that in alkaline seawater. The integrated cell also produces hydrogen and formate simultaneously with high faradaic efficiency and considerable durability. The findings in this work represent a new direction for energy-saving production of hydrogen from seawater.