Plasmon resonance enhanced palygorskite-based composite toward the photocatalytic reformation of cellulose biomass under full spectrum

Photo-driven reformation of cellulose biomass is deemed a promising technology to produce value-added chemicals. Herein, the photocatalytic conversion of cellulose to 5-hydroxymethylfurfural (5-HMF) employing a palygorskite (Pal) clay-based composite as a catalyst was reported. Pal modified with phosphoric acid (P-Pal) not only induced the growth of Cu2(PO4)(OH) nanosheets on its surface with high dispersion effectively enhancing light absorption, but also enabled intimate adsorption of catenulate cellulose in the colloidal solution. The in-situ precipitated Cu2(PO4)(OH) owned abundant Lewis acid sites and localized surface plasmon resonance (LSPR) effect, which extended the absorbance range to near-infrared (NIR) light and provided a substrate for local thermal activation. Under simulated solar light irradiation, Bronsted acid provided by P-Pal and the formed hydroxyl radicles (·OH) synergistically facilitated the cleavage of the β-1,4-glycosidic bond of cellulose to produce glucose, while the Lewis acid sites directed the selective glucose isomerization to produce 5-HMF. The 20 wt% Cu2(PO4)(OH)/P-Pal exhibited the highest 5-HMF selectivity of 72% along with remarkable reusability, and the yield of 5-HMF reached 53 mg/L even under NIR irradiation, benefiting from the immobilization and acid sites of the Pal clay.