2D/2D Heterojunction of TiO Nanoparticles and Ultrathin G-CN Nanosheets for Efficient Photocatalytic Hydrogen Evolution.

Photocatalytic hydrogen evolution is considered one of the promising routes to solve the energy and environmental crises. However, developing efficient and low-cost photocatalysts remains an unsolved challenge. In this work, ultrathin 2D g-CN nanosheets are coupled with flat TiO nanoparticles as face-to-face 2D/2D heterojunction photocatalysts through a simple electrostatic self-assembly method. Compared with g-CN and pure TiO nanosheets, 2D/2D TiO/g-CN heterojunctions exhibit effective charge separation and transport properties that translate into outstanding photocatalytic performances. With the optimized heterostructure composition, stable hydrogen evolution activities are threefold and fourfold higher than those of pure TiO and g-CN are consistently obtained. Benefiting from the favorable 2D/2D heterojunction structure, the TiO/g-CN photocatalyst yields H evolution rates up to 3875 μmol·g·h with an AQE of 7.16% at 380 nm.