Flexible bifunctional electrocatalyst (Ni@(Ni,Fe)Se2/Ni@CC) by adjusting d-band center for high-efficiency HER and overall water splitting

Abstract

Nickel foam is widely used as a collector for electrocatalysts because of its excellent electrical conductivity; however, it is prone to react with elements such as oxygen, sulfur, and phosphorus during the growth of electrode materials, which makes it brittle and fragile, thus limiting its large-scale application. In this study, bifunctional electrocatalysts with flexible multilevel Ni-based nanoclusters Ni@(Ni,Fe)Se₂/Ni@CC were synthesized on carbon cloth (CC) by hydrothermal and electrodeposition methods; these flexible electrocatalysts are convenient for subsequent industrial applications. At a current density of 10 mA cm⁻², the overpotentials of the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) reached 98 and 224 mV, respectively, exceeding the catalytic effects of most metal-based collectors. The overall water-splitting potential of the catalyst was only 1.56 V at 10 mA cm⁻², and the performance was maintained after a 24 h stability test. Ni@(Ni,Fe)Se₂/Ni@CC significantly improved the activity in alkaline environments by modulating the center of the d-band, thereby increasing the adsorption capacity of the catalyst for H ions. In this study, we improved the intrinsic activity and charge transfer of transition metal electrocatalysts by modifying the carbon cloth and constructing multilevel Ni-based nanoclusters, which provided some insights into the rational design of flexible bifunctional electrocatalysts.