Single cobalt atom anchored on N-doped graphyne for boosting the overall water splitting

Developing inexpensive and high-active electrocatalysts for overall water splitting is important to the development of future clean energy technologies. Many non-noble metal single-atom catalysts (SACs) present unsatisfactory water-splitting catalytic performance because of their intrinsic electronic structures. Here, through the density functional theory calculations, a nitrogen atom doping strategy is applied to directly tune the electronic structure of the SAC and boost their catalytic activities towards both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). By precisely manipulating N doping modes in graphyne supported single Co atom catalyst (Co@GY), the stability, electronic properties, and HER, as well as OER catalytic activities of these N-doped Co@GY catalysts are investigated. It is found that the N-induced charge redistribution on the surface of the N-doped Co@GY catalysts greatly affects their HER and OER performances. The N-induced charge density not only increases the number of active sites of Co@N-1-GY and enhances its catalytic activity for HER, but also weakens the chemisorption of oxygenated species and decreases distinctly the over-potential for OER, making Co@N-1-GY a promising bifunctional electrocatalyst for water splitting. This work offers a feasible strategy for experimental groups to properly tune the electronic structures of catalysts and improve catalytic activity.