Nitrogen-doped carbon encapsulating a RuCo heterostructure for enhanced electrocatalytic overall water splitting

Abstract

The kinetically sluggish electrochemical water splitting reaction still faces great challenges, and the rational design of excellent electrocatalysts is the key to solving the problem. Herein, an etching and pyrolysis strategy is employed to dope Ru into highly hollow nanocaged RuCo@C heterostructured catalysts using the metal–organic framework ZIF-67 as a template by adjusting the annealing temperature, which not only enhances the activity but also reduces the cost. Property studies show that the optimal heterostructured catalyst RuCo@C-350 presents outstanding electrocatalytic activities with low overpotentials to drive 10 mA cm⁻² for the hydrogen evolution reaction (HER, 91 mV) and oxygen evolution reaction (OER, 230 mV) under alkaline conditions. Moreover, RuCo@C-350 demonstrates remarkable catalytic behavior for overall water splitting in a two-electrode system with 1.56 V to drive a 10 mA cm⁻² current density in an alkaline electrolyte. The derived highly hollow heterostructure that exposes numerous active centers and accelerates the mass transportation and the strong synergistic coupling effect between the integrated components together improve the catalytic activity and stability of the composite catalyst. This work promotes an in-depth understanding of the rational construction of MOF template-induced bifunctional Ru-based electrocatalysts.