Depolymerization of recalcitrant lignin is a crucial step in realizing the full potential of transforming biomass to value-added small organic molecules. Herein, we report a photocatalytic system consisting of ultrathin CdS nanosheets decorated with first-row transition metals (M/CdS) for the direct photocleavage of lignin model compounds to small aromatic products. In the meantime, the reducing power of M/CdS is utilized to simultaneously generate another valuable product, H₂, hence eliminating the necessity of sacrificial reagents and maximizing the energy conversion efficiency. We further demonstrate that, by judiciously modulating the photocatalytic conditions, it is feasible to yield different products with very high selectivity using the same catalyst of Ni/CdS. A series of control experiments were performed to investigate the mechanistic steps of each reaction and highlight the important roles played by both solvent and base in the photocleavage of the β-O-4 bond in lignin valorization.

中文翻译：

---

使用超薄金属/ CdS的木质素模型化合物的高选择性光催化脱价

顽固性木质素的解聚是实现将生物质转化为增值的有机小分子的全部潜力的关键步骤。本文中，我们报道了一种由超薄CdS纳米片组成的光催化系统，该纳米片装饰有第一行过渡金属（M / CdS），用于将木质素模型化合物直接光裂解为小的芳香族产物。同时，利用M / CdS的还原能力同时生成另一种有价值的产物H ₂，因此消除了牺牲试剂的必要性，并最大限度地提高了能量转换效率。我们进一步证明，通过明智地调节光催化条件，使用相同的Ni / CdS催化剂以非常高的选择性产生不同的产品是可行的。进行了一系列对照实验，以研究每个反应的机理步骤，并强调了溶剂和碱在木质素增值过程中β-O-4键的光裂解中所起的重要作用。