Modulating P-S anions of graphene supported amorphous nickel-iron nanocomposites by plasma to optimize overall water splitting activity

Abstract

Hydrogen production by electrolysis of water is a key technology that has the potential to aid in the transition towards green sources of energy. In this regard, graphene-supported bifunctional electrocatalysts have shown to promote both oxygen evolution and hydrogen evolution processes. Although they are considered as one of the most potential electrocatalysts, modulation of their morphological structures and electronic configurations is challenging. Here, an efficient bifunctional electrocatalyst of graphene-supported NiFe-LDH with phosphorus-sulfur anion coordination is prepared based on the RF plasma treatment strategy. Reasonable P and S anion ratios optimize the partial coordination environment and crystal state, and effectively regulate the adsorption of OH∗, OOH∗, and protons, which consequently enhance the OER/HER performance. Plasma treatment generates vacancy defect structures for the catalyst, which modulates the surface morphology and electronic structure. Optimized graphene-supported NiFe-LDH catalysts with phosphorus-sulfur anion modulation show excellent electrocatalytic performance with 228 mV overpotentials for OER at 100 mA cm−2, in alkaline environments with excellent stability. This study offers recommendations for designing catalysts to produce effective water splitting.