Assembling γ-graphyne surrounding TiO2 nanotube arrays: an efficient p-n heterojunction for boosting photoelectrochemical water splitting

Photoelectrochemical water splitting is an excellent strategy for hydrogen generation and it is pivotal to the development of photoanodes with sufficient sunlight harvesting, rapid charge separation, and enhanced electron injection efficiency. In this work, we rationally constructed a gamma-graphyne/TiO2 (GY/TiO2) p-n heterojunction in which p-type gamma-graphyne nanosheets were distributed in the three-dimensional space surrounding TiO2 nanotube arrays. The GY/TiO2 photoanode achieves a photocurrent density of 0.75 mA cm(-2) at 1.23 V (vs. RHE), 1.7 times that of bare TiO2, and extends the electron lifetime of TiO2 from 0.51 to 1.16 ms. The improvement arises from moderate gamma-graphyne modification, contributing to broadened light absorption, the suppressed recombination of electron-hole pairs, an increase in charge transfer, and a higher injection efficiency of surface electrons. This work provides a reliable approach for the utilization and conversion of sustainable solar energy.

Automated summary

By constructing a γ-graphyne/TiO2 photoanode, the photocurrent density was increased while the electron lifetime of TiO2 was extended, which was attributed to moderate γ-graphyne modification, contributing to enhanced light absorption, suppressed recombination of electron-hole pairs, and higher injection efficiency of surface electrons.