Hydroxychloride-triggered spinel composite electrode for energy-efficient and long-lasting brine electrolysis hydrogen production

Abstract

Integrating the inherent strengths of distinct functional materials to engineer advanced composite electrodes for brine oxidation is crucial for advancing sustainable seawater electrolysis hydrogen production technology. The general approach of developing efficient electrodes is to combine a catalyst and a support material to leverage the catalyst-support interactions. In this study, a trigger-catalyst composite electrode design was put forward. Specifically, a highly oxidation-prone Co2(OH)3Cl was employed as a trigger, combined with stable CoFe2O4 catalysts to engineer a Co2(OH)3Cl@CoFe2O4 composite electrode for active and stable brine oxidation. In-situ Bode plots and first principles evidences revealed that the oxidation of Co2(OH)3Cl components promoted the activation of CoFe2O4 catalysts at low potentials to drive the oxygen evolution reaction (OER) in brine electrolytes. As a result, the Co2(OH)3Cl@CoFe2O4 electrode displayed a low overpotential of 295 mV at 100 mA cm-2 in brine electrolyte, which is outstanding among the best of Co-based electrodes for OER thus far. More importantly, the alkaline seawater electrolyzer assembled by the Co2(OH)3Cl@CoFe2O4 anode and a commercial Ni mesh cathode showed stable hydrogen production performance for 1000 h at 100 mA cm-2 and 50 h at even 1 A cm-2, suggesting the progressiveness of the Co2(OH)3Cl trigger/CoFe2O4 catalyst composite electrode in driving brine electrolysis hydrogen production.