Heat Treatment-Assisted Optimization of the Water Splitting Performance of CoCrNi0.5Ti0.3V0.2Al0.4 Eutectic High-Entropy Alloy

In this study, the synergistic tuning mechanism of heat treatment (600, 800, and 1000 °C) and dealloying (40, 60, and 80 °C) on the microstructure and electrocatalytic performance of an FCC + BCC-type CoCrNi0.5Ti0.3V0.2Al0.4 eutectic high-entropy alloy (EHEA) was systematically investigated. The findings indicate that with an increase in heat treatment temperature, there is a gradual increase in grain size and a change in the fraction of the two phases. Notably, heat treatment at 800 °C resulted in an FCC-dominated dual-phase structure with uniformly refined grains. As the dealloying temperature increased, the pore size also increased, leading to a uniform distribution of the internal FCC and BCC phases. The sample subjected to heat treatment at 800 °C and dealloying at 80 °C exhibited an OER overpotential of only 265 mV and a Tafel slope of 67.84 mV/dec, significantly enhancing the electrocatalytic activity and stability of the alloy. This study elucidates the mechanism by which the combination of heat treatment and dealloying processes optimizes the electrocatalytic performance of eutectic high-entropy alloys, providing a novel strategy for the design of non-precious metal electrocatalysts.