Fabrication of TiO2 nanorods/γ-graphyne boosting junction-driven charge transfer for efficient photoelectrochemical water splitting

Photoelectrochemical (PEC) water splitting is a viable method for converting renewable solar energy into storable chemical energy. Herein, the newly emerged two-dimensional sp- and sp2-carbon hybridized graphyne sheets were successfully coupled with thin film-like arrays of titanium dioxide nanorods, forming an efficient 2D-1D heterojunction. The microstructure and composition of obtained γ-graphyne/TiO2 films were well characterized. And enhanced photoelectrochemical properties were demonstrated. The γ-graphyne/TiO2 photoelectrode achieves a photocurrent density of 1.31 mA/cm2 at 1.23 V (vs. RHE), which is 1.7 times over that of pristine titanium dioxide. An improvement of photoconversion efficiency by 2.2 folds was observed. The high PEC activity of γ-graphyne/TiO2 originates from band alignment and interfacial junction between π-conjugated graphyne sheets and TiO2 nanostructure, greatly promoting charge transfer and diminishing defective excitation and recombination. By virtue of the γ-graphyne nanosheets, largely increased number of useful photons and catalytic active sites are triggered. This work provides a reference for the photoelectrochemical application of semiconductive γ-graphyne and a specific and proven method for the utilization of solar energy.