Photocatalytic oxidation of glycerol using x/TiO2 (with x= Cu, Ag, and Cu-Ag) to dihydroxyacetone and other value-added products

A set of catalysts was prepared by the surface decoration of TiO2 (Degussa-P25) with noble metal (Ag), non-noble metal (Cu), and bimetallic (Cu-Ag) nanoparticles, which were evaluated for photocatalytic glycerol oxidation under low-wattage irradiation (commercial-led white light, 1.8 W), basic free conditions and the assistance of hydrogen peroxide. Dihydroxyacetone and glyceraldehyde were obtained as the primary oxidation products. After 8 h, the Ag/TiO2 catalyst showed the highest photocatalytic activity (glycerol conversion of 74%) and dihydroxyacetone selectivity of 80%. However, the highest selectivity toward dihydroxyacetone (86%) was achieved with the Cu/TiO2 catalyst for a glycerol conversion of 55%. Thus, the results confirm the crucial role of nanoparticles in inducing a surface plasmon resonance effect (Schottky junction for metallic Ag) and a heterojunction effect (for CuO and Cu2O) that allows light absorption within the visible region.