Reversion of catalyst valence states for highly efficient water oxidation

The conventional four-electron electrochemical process which drives water splitting requires a high overpotential and is energy inefficient. Thus, it is highly desirable to develop an alternative theoretical framework for catalyst and electrolyzer design that can enhance the energy efficiency. Herein, we report an occurrence of spontaneous anode reduction during the oxygen evolution reaction (OER), which involves continuous generation of oxygen amid a reduction in the valence state of a specially prepared catalyst. This points to the existence of a low-overpotential electrocatalytic pathway. Guided by this finding, we propose an intermittent electrocatalytic mode, which is able to significantly reduce the OER overpotential by utilizing the low formation energy of changing valence states. Our work presents a novel perspective on catalyst design and an innovative electrocatalytic mode for water oxidation with low energy consumption.