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

Hydrogen (H-2) produced by electrochemical(EC) and photoelectrochemical(PEC) overall water splitting is regarded as promising clean energytechnologies, while exploring low-cost and high-efficient catalystsremains a challenging task. Herein, we demonstrate the catalytic activitiesof nitrogen-doped triphenylene-graphdiyne (N@TP-GDY) monolayers usingfirst principles calculations in combination with nonadiabatic moleculardynamics. Our results show that the introduction of sp/sp(2)-hybridized N atoms can greatly regulate the electronic structuresof TP-GDY monolayer, presenting appealing bifunctional EC performancewith low overpotentials of 0.06 and 0.49 V for hydrogen evolutionreaction (HER) and oxygen evolution reaction (OER), respectively.Meanwhile, the redox ability of the photogenerated electrons and holesin the N@TP-GDY systems is strong enough to drive HER and OER processesat acid and alkaline conditions, respectively. Moreover, the lifetimeof the photogenerated carriers is greatly improved up to 729 ps inthe 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 promisingphotocathode or photoanode in the PEC cells. These intriguing resultshighlight the role of N-atom doping in the TP-GDY systems for overallwater splitting, providing useful insights into the rational designof metal-free catalysts for sustainable production of H-2.