Heterojunction engineering decorated TiO₂/ZnO three-dimensional hierarchical structure with g-C₃N₄ for solar driving water splitting

Improving the carrier separation efficiency plays a decisive role in designing and constructing a high-efficiency photocatalysis reaction system. Derived from providing a directional transport channel for photogenerated carriers, three-dimensional (3D) nanostructures greatly improve the charge separation efficiency. Herein, TiO2/ZnO (TZ)/g-C3N4 3D hierarchical nanostructure was constructed to artificially simulate photosynthesis of green plants. The optimal TZ/g-C3N4 photoanode exhibits a photocurrent density of 1.46 mA/cm(2) at 1.23 V versus reversible hydrogen electrode potential, 1.6 times that of pure TiO2 (0.9 mA/cm(2)). Moreover, under constant illumination (100 mW/cm(2)), the hydrogen production reached 80 mu mol/cm(2) within 180 min. It is worth noting that the TZ/g-C3N4 photoanode shows surprising stability, which is an important indicator for the practical application of the photoelectrode. The excellent photoelectrochemical performance benefits from the following two aspects: TZ nanotree structure provides a directional transport channel for photogenerated carriers, and the modification of TZ by g-C3N4 extends the response range to the visible region.