Engineering 2D multi-hetero-interface in the well-designed nanosheet composite photocatalyst with broad electron-transfer channels for highly-efficient solar-to-fuels conversion

Abstract The hetero-interface quality and area in the semiconductor heterostructure are important to the photocatalytic performance of the heterostructure. The 2D hetero-interface between two 2D semiconductors has been widely proved to enhance the photocatalytic performance, because the larger contact area of the hetero-interface can effectively improve the charge separation behavior. However, engineering high-quality 2D multi-hetero-interface in the well-designed semiconductor composite to further enhance the charge separation and utilization is still a big challenge. Herein, we constructed the 2D multi-hetero-interface in the well-designed nanosheet (NS) composite photocatalyst through an in-situ oxidation treatment combined with the electrostatic self-assembly strategy. The negatively-charged binary Ti3C2Tx/(001)TiO2 heterojunction NSs with the intimate 2D contact interface was fabricated through a facile in-situ oxidation method, while the protonated g-C3N4 NSs were positively charged. Thus, the spontaneous electrostatic attraction behavior between the above opposite-charged materials of the Ti3C2Tx/(001)TiO2 heterojunction and the g-C3N4 NSs enables the 2D multi-hetero-interface to be constructed in the Ti3C2Tx/(001)TiO2/C3N4 NSs. As such, the 2D multi-hetero-interface offers broad electron-transfer channels to enhance the charge separation and utilization. Upon simulated sunlight irradiation, the optimal Ti3C2Tx/(001)TiO2/C3N4 NSs achieved about 4-fold enhancement on the photocatalytic H2 generation and 3-fold improvement on the photocatalytic CO2 reduction as compared to the pure (001)TiO2 or g-C3N4 NSs.