One-Pot Photocatalytic Cleavage of Lignin beta-O-4 Models by Dehydrogenation-Hydrogenolysis

Photocatalyticdepolymerization of lignin beta-O-4alcohol was achieved through the one-pot method, achieving the goalof simultaneously utilizing solar energy and biomass energy. Valorizing lignin into valuable chemicals requires theselectivebreaking of a large number of C-O bonds found in the beta-O-4structure. In this study, we present a one-pot strategy that utilizestwo NiO/TiO2 catalysts for the photocatalytic depolymerizationof beta-O-4 alcohols. The S-1.6%NiO/TiO2 catalyst is used for the dehydrogenation of beta-O-4alcohols at 450 nm. Then, the L-0.8%NiO/TiO2 catalyst isemployed for the hydrogenolysis of beta-O-4 ketonesat 365 nm. Remarkably, the dehydrogenation-hydrogenolysis tandemreaction can be conducted in one pot, which affords high yields ofketones and phenols (up to 89%) from beta-O-4 alcohols.Additionally, the L-0.8%NiO/TiO2 catalyst prepared in thisarticle is the smallest NiO/TiO2 photocatalyst reportedto date, and the size of NiO in the S-1.6%NiO/TiO2 catalystis even small enough to enter the lattice of TiO2. We successfullyregulated the reaction selectivity by controlling the loading methodand the amount of NiO. Our work offers a promising solution for efficientlycleaving target bonds in lignin and provides insights into the designof efficient photocatalysts.