Enhanced oxygen and hydrogen evolution reaction by zinc doping in cobalt–nickel sulfide heteronanorods

Abstract

AbstractDeveloping highly efficient electrocatalysts for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) is critical to enable electrical‐to‐hydrogen energy conversion technologies to reality. Herein, zinc‐doped cobalt sulfide‐modified nickel sulfide (ZCNS) heteronanorod hybrid electrocatalysts are prepared through a facile hydrothermal method to enhance the electrocatalytic performance of cobalt‐nickel sulfide. The doping of Zn optimizes the electronic structure of cobalt‐nickel sulfide thus improving the conductivity and charge transfer ability of cobalt‐nickel sulfide. In addition, benefiting from the hierarchical structure of one‐dimensional nanorods and three‐dimensional Ni foam, abundant catalytically active sites and fast ion and charge transportation are obtained. As a result, the optimal zinc doped cobalt‐nickel sulfide hybrid presents overpotentials of 138 and 235 mV to achieve a current density of 10 mA/cm2 in 1.0 M KOH for HER and OER, respectively. Assembled as an electrolyzer for overall water splitting using the heteronanorod hybrids as both anode and cathode catalysts, the low cell voltage of 1.56 V at 10 mA/cm2 is achieved, which is similar to that of the IrO2‐Pt/C couple.