Cups Ultrafine Nanoparticles Anchored into N-Doped Carbon Framework for Bifunctional Water Splitting

Abstract

Hydrogen has been considered as the green energy carrier to substitute gradually depleted fossil fuels due to its virtues holding high energy density and zero environmental discharge. Electrocatalytic water splitting is one of the most effective approach to generate hydrogen fuel, which involves two half reactions, namely hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The design of efficient and low-cost electrocatalysts to reduce the large energy barriers of water splitting is challenging. Nanosizing of the electrocatalysts could provide new insight into understanding the catalytic reaction at nanoscale and even molecular level. Here, a novel ultrafine CuPS nanoparticles anchored into N-doped carbon framework (CuPS/NC) was proposed as advanced electrocatalyst for full water splitting. Density functional theory calculations revealed the synergistic electronic interaction between S and P, leading to optimal electronic structure and hydrogen adsorption free energy, thus facilitating HER kinetics. The highly open yet interconnected 3D framework creates a large surface area, exposing abundant active sites and providing convenient charge and ionic diffusion pathway. The ultrafine CuPS nanoparticles enable to fully utilize accessible edge sites. As a result, the obtained CuPS/NC exhibits relatively low overpotentials and small Tafel slopes for both HER and OER, as well as superior performance toward full water splitting.