Self-supported Co3O4@Zn–CoNi2S4/NF core–shell nanoarrays as an efficient bifunctional electrode for overall water splitting

Abstract

It is a crucial matter to develop bifunctional transition metal catalysts for water electrolysis. In this study, we fabricate a Co₃O₄@Zn–CoNi₂S₄ core–shell heterostructure supported on nickel foam (Co₃O₄@Zn–CoNi₂S₄/NF). The compound structure can generate more active centers and exhibit some unique characteristics. Moreover, the doping of Zn further enhances the catalytic performance. It can optimize the lattice structure of the Co₃O₄@CoNi₂S₄/NF heterostructure and reduce the reaction energy barrier effectively, which can meet the relatively strict requirements of high-performance electrocatalysts. This material can be used as an efficient bifunctional electrocatalyst. In 1 M KOH electrolyte, the material shows excellent electrocatalytic performance for OER and HER. It possesses a low overpotential of 190 mV at 10 mA cm⁻² for OER and 120 mV at 10 mA cm⁻² for HER. Also, it maintains long-term stability. The Co₃O₄@Zn–CoNi₂S₄/NF electrolytic cell acts as a two-electrode system for overall water splitting. It needs a battery voltage of 1.45 V to drive the current density to 10 mA cm⁻². This research has proved that combining metal doping with heterogeneous interface design is a feasible strategy for developing high-performance bifunctional electrocatalysts.