0D/2D Co0.85Se/TiO2 p–n heterojunction for enhanced photocatalytic H2 evolution

Abstract

Photocatalytic H₂ evolution is a promising way to obtain green H₂ due to its clean and sustainable characteristics. Herein, a series of 0D/2D Co_0.85Se/TiO₂ heterojunctions were fabricated through a successive two-step hydrothermal strategy. Among them, 15%-Co_0.85Se/TiO₂ displays the most excellent H₂ rate of 2312.5 μmol g⁻¹ h⁻¹, which is 10.3 times and 10.8 times higher than that of TiO₂ and Co_0.85Se, respectively. And the H₂ production rate per electrochemically active surface area of 15%-Co_0.85Se/TiO₂ is 127.41, which is obviously more than that of TiO₂ (14.17) and Co_0.85Se (5.39). Based on the core-level alignment method and free radical capture tests, the enhanced activity mainly resulted from the higher electrochemically active surface area and the formation of a p–n heterostructure between TiO₂ and Co_0.85Se. This research provides a strategy for the development of noble metal-free nanocomposites for efficient photocatalytic H₂ production.