Enhancing photocatalytic cleavage of C-C bonds in lignin model substrates by ternary nanocomposite of g-C3N4/rGO/CdS using rGO as electronic mediators

Depolymerizing lignin into aromatic monomers with high yield and selectivity via photocatalysis remains a challenging task. Herein, we introduced reduced graphene oxide (rGO) nanosheets as solid electronic mediators and successfully synthesized g-C3N4/rGO/CdS ternary nanocomposites using a simple multi-step assembly strategy. The photocatalysts can efficiently break the C-C bond of lignin under simulated sunlight conditions. The characterization results demonstrate that the loading of CdS effectively enhances the light absorption range and accelerates the transfer of photogenerated charge carriers. Simultaneously, the introduction of rGO inhibits the recombination of electron-hole pairs. When using the & beta;-O-4 model substrate, a 95% conversion rate could be achieved with yields of 71% benzaldehyde and 69% phenyl formate, which are 3.09 times and 3.63 times higher than that of pure g-C3N4, respectively. Our research highlights the importance of energy band structure engi-neering and electronic mediator design in developing efficient photocatalysts for breaking C-C bonds of lignin.

Automated summary

In this study, a challenging task of depolymerizing lignin into aromatic monomers with high yield and selectivity via photocatalysis was achieved. Reduced graphene oxide (rGO) nanosheets were introduced as solid electronic mediators to synthesize g-C3N4/rGO/CdS ternary nanocomposites. The photocatalysts efficiently broke the C-C bond of lignin under simulated sunlight conditions. Characterization results showed that the loading of CdS enhanced light absorption range and accelerated the transfer of charge carriers, while the introduction of rGO inhibited recombination of electron-hole pairs. Using the β-O-4 model substrate, a 95% conversion rate was achieved with higher yields of benzaldehyde and phenyl formate compared to pure g-C3N4. Our research highlights the importance of energy band structure engineering and electronic mediator design in developing efficient photocatalysts for breaking C-C bonds of lignin.