Upconversion enhanced photocatalytic conversion of lignin biomass into valuable product over CeVO4/palygorskite nanocomposite: Effect of Gd3+ incorporation

Photocatalysis has great potential on converting lignin biomass to value-added chemicals. Herein, dendritic-like CeVO4 in situ grew on the phosphoric acid-activated palygorskite (P-Pal) nanorod surface and 5% incorporation of Gd3+ ions achieved the strongest up-conversion property, which converted near infrared (NIR) light into UV and visible light boosting the absorption range of solar energy. Under optimized 6 h sunlight irradiation, the highest conversion rate of sodium lignosulfonate (SLS) can reach 73.2%, and the vanillin yield can reach 4.5 mg/gSLS. Gd3+: CeVO4 and P-Pal formed well-defined Z-scheme heterojunction which retained strong redox ability of charge carriers, and·O2- acted as the main reactive species for the photocatalytic conversion of SLS to valuable products. Notably, abundant Lewis acid sites and Brønsted acid sites induced by phosphoric acid acted as active sites boosting the cleavage of C-C bonds in SLS. Present work offers an alternative for mineral-based catalysts toward photocatalytic conversion of biomass.