Cooling water to near freezing breaks the activity-stability trade-off of water oxidation electrocatalysis.

Abstract

Temperature is a fundamental parameter in reaction kinetics, typically accelerating rates according to the Arrhenius law. In catalytic systems, however, competing pathways often respond differently to temperature, allowing the selective promotion of desired reactions while suppressing undesired ones through temperature modulation. Here we show that regulating the temperature near the freezing point of water can resolve the activity-stability trade-off in the oxygen evolution reaction on manganese dioxide. Although lowering the temperature decreases water oxidation rates, catalyst degradation through permanganate formation is suppressed more effectively, extending catalyst lifetime. Counterintuitively, further cooling below 0 °C accelerates permanganate formation, yielding an optimum temperature near 0 °C that balances activity and stability. This anti-Arrhenius behaviour, arising from electrolyte supercooling, is a rare example of anomalous temperature-dependent electrocatalysis under subzero conditions. Our findings highlight temperature regulation as a viable strategy for enhancing catalytic lifetime, with implications for electrochemical systems operating in wintertime and in polar and extraterrestrial environments.