Heat-induced magnetic transition accelerates redox couple mediated electrocatalytic water oxidation in alkaline media

Abstract The redox couple oxidation as an initial step for oxygen evolution reaction (OER) may be key for high electricity consumption in electrochemical redox couple mediated water splitting. Here, we report a heat-induced magnetic transition strategy to speed up the oxidation kinetics of redox couples. The activation energy of Ni2+/Ni3+ redox couple oxidation was significantly decreased by heating the Ni0.5Fe0.5OxHy OER catalyst above Néel temperature (TN) of 70oC. In such a strategy, the heat in stead of electricity to overcome the spin flipping of Ni2+/Ni3+ oxidation through the heat-sensitive ferrimagnetic-to-paramagnetic spin state changes. The efficient heat-electricity coupling enables Ni0.5Fe0.5OxHy to produce the lowest OER overpotential of 170 mV at 100 mA cm-2 at 90 oC in alkaline electrolyte, outperforming the benchmark IrO2 catalyst. Our findings demonstrate the application potential of heat-sensitive magnetic materials in the field of electrocatalysis, which may inspire insights into designing of multi-energy complementary OER devices.