Hierarchical Graphdiyne@NiFe layered double hydroxide heterostructures as a bifunctional electrocatalyst for overall water splitting

Abstract

Hydrogen is an ideal energy with little impact on the environment to tackle the intense energy crisis. Development of highly efficient electrocatalysts for low–cost hydrogen production from water splitting is vital for the real-world practical applications. Herein, a three dimensional hierarchical graphdiyne (GDY)@NiFe layered double hydroxide (LDH) heterostructured catalyst toward overall water splitting is developed by coupling NiFe LDH and GDY growth on copper foam (CF). The catalyst exhibits high electrocatalytic activities in both oxygen evolution reaction (OER) and hydrogen evolution reaction with overpotentials of 220 mV and 163 mV at a current density of 10 mA cm−2, respectively. The Tafel slope for OER is 39.33 mV dec−1, which is much lower than that of the only NiFe LDH/CF with a value of 112 mV dec−1. Thus, the GDY@NiFe LDH/CF heterostructure electrocatalyst leads to an improvement in the overall water splitting activity, with a current density of 20 mA cm−2 at the voltage of 1.512 V. Density functional theory calculation indicates that the synergetic effects of 3d orbit of transition metal atoms and carbon–carbon triple bonds in GDY are responsible for the bifunctional excellent electrocatalytic activity for overall water splitting.