Efficiently and selectively photocatalytic cleavage of C[sbnd]C bond by C3N4 nanosheets: Defect-enhanced engineering and rational reaction route

Abstract

Photocatalytic cleavage of CC bond in lignin under mild conditions transforms solar energy into high value-added aromatic compounds. However, the limited understanding of cleavage mechanisms and the catalyst structure-performance relation obstruct the rational design of efficient photocatalysts. Reported herein is the construction of porous carbon nitride (C3N4) with carbon vacancies as heterogeneous photocatalysts via a sequential self-assembly and diol-induced thermal exfoliation. In the photocatalytic cleavage of βO4 ether bonds, carbon vacancies in C3N4 can serve as the trapping site to suppress the recombination of photogenerated charge, and endow the C3N4 with high level of N and thus make it easier for the oxidation of Cβ–H, contributing to the enhancement of performance. Furthermore, the experimental result and in situ ATR-SEIRAS spectra unveil that O2 could facilitate the cleavage of CC bond but is not indispensable in this process, which brings new fundamental understanding of βO4 bonds cleavage.