Heat-Triggered Ferri-to-Paramagnetic Transition Accelerates Redox Couple-Mediated Electrocatalytic Water Oxidation

Redox couple oxidation as an initial step of water oxidation may be key for high electricity consumption in the electrochemical oxygen evolution reaction (OER). Here, a heat-induced magnetic transition strategy is reported to speed up the oxidation kinetics of redox couples. The activation energy of Ni2+/Ni3+ redox couple oxidation is sharply decreased by heating the Ni0.67Fe0.33OxHy catalyst above a Curie temperature (T-c) of 70 degrees C. In such a strategy, heat instead of electricity drives the spin flipping of Ni2+/Ni3+ oxidation through heat-sensitive ferri-to-paramagnetic spin state changes. As a result of magnetic transition-assisted efficient heat-electricity coupling, Ni0.67Fe0.33OxHy exhibits the lowest OER overpotential of 221 mV at 100 mA cm(-2) at 90 degrees C in alkaline electrolytes, outperforming the benchmark IrO2 catalyst. The findings provide new insights into the design of efficient heat-electricity complementary OER devices.

Automated summary

A heat-induced magnetic transition strategy is reported to speed up the kinetics of redox couple oxidation. By using heat instead of electricity, the activation energy of the oxidation reaction is decreased, leading to improved efficiency in the oxygen evolution reaction.