Surface electronic structure reconstruction of binary metal spinel oxide by sulfur inducing for superior water electrolysis

The selection of electrocatalysts for the oxygen evolution reaction (OER) is crucial for hydrogen production from water electrolysis. Binary metal spinel oxide CuCo2O4 has emerged as a promising OER catalyst due to its unique multi-valence characteristics and cost-effectiveness, but its practical application has faced challenges stemming from limitations in its electronic structure and a scarcity of active sites. Herein, we have introduced sulfur (S) into CuCo2O4, leading to a significant increase in oxygen defects and a partially amorphous phase formation. The optimized S-CuCo2O4/CC electrocatalyst exhibits an overpotential of only 216 mV at 10 mA cm-2. The excellent performance originates from reconfiguring the electronic structure upon S introduction, leading to optimized intermediates' adsorption/desorption and an increase in active sites by forming a partially amorphous phase. Meanwhile, due to the abundance of active S sites and enhanced kinetics, the catalyst demonstrates outstanding performance in the hydrogen evolution reaction (HER). It exhibits a promising potential for overall water splitting (OWS) with a low voltage of 1.67 V at 10 mA cm-2. This study synergistically combines doping, vacancy, and amorphization strategies to thoroughly analyze their impact on catalytic performance, offering valuable insights for the design of efficient and stable non-noble metal catalysts.