Significance of slight ambient temperature variation on the electrocatalyst performance toward oxygen evolution reaction

Hundreds of oxygen evolution reaction (OER) electrocatalysts have been developed over the past few decades, and their performances are evaluated and compared at ambient temperature. However, the effect of ambient temperature variation on OER electrocatalyst performance has received less attention, which may play a remarkable role in the electrocatalytic activity. In this work, we systematically investigated the influence of ambient temperature variation on electrocatalyst performance toward OER. The results show that the slight ambient temperature variation has a significant effect on OER catalyst performance based on the changes of overpotential (10 mA cm⁻²) and Tafel slope. Both remarkable chances are observed on transition metal (Ni) and noble metal (IrO₂) electrocatalysts, and the overpotentials decrease around 81 mV with a temperature increase by 20 °C (from 10° to 30°C) for both Ni and IrO₂ electrocatalysts with the Tafel slope drops of 36.9 and 29.5 mV dec⁻¹, respectively. A similar trend is also found in the electrochemically active surface (ECSA) normalized performance and the charge transfer resistance. This study demonstrates that reporting the actual operating temperature for OER is not only recommended but also necessary to evaluate and compare electrocatalyst activities from different materials systems properly, and neglecting the ambient temperature variation effect can highly mislead conclusions.