Mechanochemical Construction 2D/2D Covalent Organic Nanosheets Heterojunctions Based on Substoichiometric Covalent Organic Frameworks.

Combining different semiconductor materials to construct heterojunctions is a promising method to achieve efficient photocatalysis; however, it is still a challenge to accurately construct heterojunctions through molecular regulation. In this work, we take advantage of the remaining aldehyde groups in a substoichiometric covalent organic framework (denoted as PTO-COF) to achieve precise construction of covalently linked 2D/2D covalent organic nanosheets (CONs) heterojunctions through mechanochemical methods. The ultrathin structure of CONs endowed them with superior photoinduced charge generation and separation. Additionally, the energy bands of two CONs materials in heterojunctions were precisely coupled in a Z-scheme by the well-designed covalent linkages, which lead to a 190% enhancement of photocatalytic degradation efficiency for PTO/TpMa CONs heterojunctions as compared with pure COFs. This work provides new insights for design and synthesis of innovative 2D organic heterojunction photocatalysts.