Computational studies on triphenyldiyne as a two-dimensional visible-light-driven photocatalyst for overall water splitting

The high carrier mobility, porous configurations and tunable electronic structures of two-dimensional (2D) carbon materials hold great promise in energy conversion and storage. However, few of them is capable for photocatalytic overall water splitting. Here, by means of first-principles calculations within the quasi-particle approximation and Bethe-Salpeter equation, we demonstrated a novel framework of triphenylenes (sp2) and acetylenic linkages (sp), namely triphenyldiyne (TDY) owns the electronic band structure suitable for photocatalytic overall water splitting along with pronounced optical absorbance in visible light. The redox ability of the photogenerated electron is high enough to drive hydrogen evolution reaction (HER). Through Ni doping to TDY, the overpotential for oxygen evolution reaction (OER) can be reduced to match the redox ability of the photogenerated holes, enabling the photocatalytic overall water splitting in the sunshine without the need of sacrificial reagents. This work offers not only a low-cost, earth-abundant and environmental-friendly photocatalyst, but also a promising strategy for designing highly-efficient photocatalysts for overall water splitting.