Preparation of Z-scheme AgI/Bi2Sn2O7 hybrids for profound C C/C O bonds cleavage in lignin β‑O‑4 ketone models
Chunli Jiang, Sixue Zhang, Shuaihong Chen, Xingdong Yao, Hongbing Ji, Yexiang Tong
Abstract
In the context of attaining carbon neutrality , photocatalytic cleavage of the C C/C O bonds between the β-O-4 structure into high-value products offers an environmentally friendly pathway. To simultaneously activate both C C and C O bonds for maximizing the utilization of lignin to yield high-value products requires the construction of highly active and selective photocatalysts . However, enhancing the efficiency and selectivity of photocatalysts for lignin degradation buffering unsuitable redox potential and rapid recombination of photogenerated carriers. Herein, we report that a direct Z-scheme heterojunction (AgI/Bi 2 Sn 2 O 7 ) as confirmed by various characterizations. The construction of the Z-scheme AgI/Bi 2 Sn 2 O 7 heterojunction was essential to efficiently separate the photoexcited carriers and then improve their redox capability. Due to its smart design, the lignin β-O-4 model compound was simultaneously activate both C C and C O bonds. Under solar illumination (AM1.5), the β-O-4 lignin molecule model achieved a conversion rate of 95.2 %, and the main product (guaiacol and p-anisaldehyde) yields were 87.6 % and 76.5 %, respectively. Mechanistic studies indicate that the efficient cleavage of C C/C O bonds mainly involved a photoexcited electron-hole-coupled redox mechanism. This finding offers insight into the high-performance charge transfer mechanism of heterogeneous interfaces, which could potentially inform the design of advanced photocatalytic systems in the depolymerisation of lignin.