Ultrathin 2D/2D Cd0.9Zn0.1S/Co0.85Se Schottky heterojunction for high-performance aromatic alcohol splitting to produce H2 and aldehyde.

Heterojunction engineering, particularly 2D/2D heterojunction involving ultrathin 2D materials, has garnered increasing attention due to the combined advantages of 2D atomic-scale nanostructure and the heterojunction effect, offering significant potential for enhancing photocatalytic performances. Here, we synthesize an ultrathin 2D/2D Schottky heterojunction composed of ∼1.50 nm Cd0.9Zn0.1S nanosheets and ∼ 0.66 nm Co0.85Se nanosheets via a simple electrostatic self-assembly strategy. This unique sub-5 nm ultrathin 2D/2D heterostructure forms extensive heterojunction interfaces with intimate contact, generating abundant charge-transfer pathways and numerous active sites, while significantly shortening the charge carrier diffusion length. Additionally, the integration of 2D Co0.85Se enhances the adsorption of aromatic alcohols onto the Cd0.9Zn0.1S surface due to the altered electronic states caused by the formation of Schottky heterojunction. As a result, the ultrathin 2D/2D Schottky heterojunction effectively boosts photocatalytic splitting of biomass-derived aromatic alcohols, producing H2 and aldehydes simultaneously. The optimized Cd0.9Zn0.1S/Co0.85Se composite achieves H2 and benzaldehyde production rates of 3948.2 and 3878.5 μmol g-1 h-1, approximately 5.8 times higher than pure Cd0.9Zn0.1S. The work demonstrates the potential for the fabrication of ultrathin 2D/2D heterojunctions for high-performance conversion of biomass and its derivates to produce H₂ and value-added chemicals.