Kinetic study of HER inhibition and OER promotion with selenization on Rh/Ni(OH)2 catalysts

The rational design and construction of efficient and stable bifunctional electrocatalysts remain a significant challenge in advancing the development of overall water splitting technology. In this work, Rh/Ni(OH) 2 and Rh/Ni 3 Se 4 catalysts are successfully fabricated on nickel foam (NF) substrates for cathodic hydrogen evolution reaction (HER) and anodic oxygen evolution reaction (OER), respectively. The influence of selenization on the kinetics of the HER and OER catalyzed by Rh/Ni(OH) 2 is systematically investigated. Results demonstrate that selenization ( Rh/Ni 3 Se 4 ) promotes the generation of high-valent Ni and significantly reduces the charge transfer resistance, thereby enhancing the OER activity. However, selenization increases the adsorption and desorption energy barriers of H intermediates, leading to a decrease in HER performance. At a current density of 10 mA cm −2 , the HER overpotential of the Rh/Ni 3 Se 4 /NF catalyst increases by 19 mV while the OER overpotential decreases by 50 mV compared to Rh/Ni(OH) 2 /NF. Notably, an asymmetric electrolyzer utilizing these catalysts operates stably for over 800 h at a current density of 500 mA cm −2 and maintains stability for 1000 h in start-stop cycle tests. This work provides a theoretical basis and experimental reference for the rational design of selenide catalysts. • Rh/Ni(OH) 2 /NF for cathodic HER and Rh/Ni 3 Se 4 /NF for anodic OER were prepared using hydrothermal and impregnation methods. • Selenation promotes high-valent Ni formation but increases the adsorption/desorption energy barrier for H intermediates. • The prepared catalyst exhibits excellent stability under various conditions.