Enhancing Photocatalytic beta-O-4 Bond Cleavage in Lignin Model Compounds by Silver-Exchanged Cadmium Sulfide

Photocatalytic conversion of lignocellulose to valuable aromatics has significant potential for applications in biorefineries. The photocatalyst efficiency of lignocellulose conversion is typically limited by the buffering redox system in combination with oxidation and reduction of the photoexcited holes and electrons, respectively, which ensures high charge-recombination rates. Herein, Ag+-exchanged CdS is employed for easy photoexcited electron transfer to the oxidized intermediate, which results in a marked increase in the conversion yield with high product selectivity under mild reaction conditions without any additives. The conversion yield of the lignin model compound under 6 W blue LED illumination is nearly 100% and only cleaved aromatic compounds are formed. The efficient photoredox CdS catalyst obtained via photoexcited electron-hole coupled transfer derived from an appropriate Ag+ exchange affords a promising method for lignocellulose conversion with reduced energy consumption.