Nitrogen-Doped Triphenylene-Graphdiyne as Metal-Free Multifunctional (Photo)Electrocatalysts for Overall Water Splitting

Abstract

Hydrogen (H2) produced by electrochemical (EC) and photoelectrochemical (PEC) overall water splitting is regarded as promising clean energy technologies, while exploring low-cost and high-efficient catalysts remains a challenging task. Herein, we demonstrate the catalytic activities of nitrogen-doped triphenylene-graphdiyne (N@TP-GDY) monolayers using first principles calculations in combination with nonadiabatic molecular dynamics. Our results show that the introduction of sp/sp2-hybridized N atoms can greatly regulate the electronic structures of TP-GDY monolayer, presenting appealing bifunctional EC performance with low overpotentials of 0.06 and 0.49 V for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Meanwhile, the redox ability of the photogenerated electrons and holes in the N@TP-GDY systems is strong enough to drive HER and OER processes at acid and alkaline conditions, respectively. Moreover, the lifetime of the photogenerated carriers is greatly improved up to 729 ps in the N@TP-GDY structures compared with that of pristine TP-GDY monolayers (110 ps). This means that the N@TP-GDY monolayers can serve as a promising photocathode or photoanode in the PEC cells. These intriguing results highlight the role of N-atom doping in the TP-GDY systems for overall water splitting, providing useful insights into the rational design of metal-free catalysts for sustainable production of H2