Visible-Light Photoreforming of Biomass Derivatives through MBiO-P25 Heterostructures: Study of the Influence of Metals (M = Cu, Ni, Zn, Co)

In this work, MBiO-P25 (M = Cu, Ni, Co, Zn) composites are successfully synthesized by a simple ball milling method by varying some parameters (rotation speed, rotation time, metal/TiO ratio) to optimize the preparation conditions. The noble metal-free TiO-based photocatalysts are used to carry out the partial oxidation of glucose and glycerol with the simultaneous H production under simulated solar light irradiation. Starting from glucose, 2.6 mmol of H are obtained with a conversion of 34%, along with arabinose, formic acid and gluconic acid as main intermediates. By using glycerol, 3.2 mmol of H are produced, with 17% conversion and the production of dihydroxyacetone and glycolic acid. The composites exhibit higher activity than pure P25 and CuBiO (CBO). The produced H amount is comparable to that reported in the literature by using Pt–TiO photocatalysts. This study offers a paradigm for the future design of bifunctional photocatalysts for simultaneous noble metal-free H production and biomass valorization under environmentally friendly conditions with a possible scale up of the process.