Construction of a hollow heterojunction interface to accelerate the photocatalytic cleavage of lignin C-O bonds.

Photocatalytic splitting of the C-O bond is regarded as a prospective strategy for transforming lignin, and it is imperative to develop novel photocatalysts with effective photogenerated charges separation and solar absorption capacity. Herein, a novel hollow ZIF-8/CdS heterostructure photocatalyst was synthesized for the catalytic splitting of lignin C-O bonds. The photocatalytic cleavage rate of C-O bond of ligin β-O-4 reached 30.3∙mmol∙h∙g within 20 min under visible light exposure. It is noteworthy that the utilization of intricate natural lignin molecules in this photocatalytic system has yielded successful depolymerization. The DFT and XPS results indicate a potential unidirectional electron migration from ZIF-8 to CdS in ZIF-8/CdS composites transfer. This electron transport path follows the direct Z-scheme heterostructure mechanism, resulting in the generation of an internal electric field between ZIF-8 and CdS. Impressively, the synergistic combination of the hollow structure and Z-scheme heterostructure effectively enhances the efficiency of charge carrier separation and maintains a robust redox potential, thereby facilitating C-radical generation. This study proposes a novel photocatalyst design strategy that integrates hollow structures and Z-scheme heterojunctions, with the aim of targeting the depolymerization of the C-O bond in lignin.