Fe-Loaded Montmorillonite/TiO₂ Composite as a Promising Photocatalyst for Selective Conversion of Glucose to Formic Acid under Visible-Light Irradiation

The development of efficient and inexpensive photocatalysts for the production of high-value chemicals from the photoreforming of biomass is a highly attractive strategy to establish the production of chemicals from sustainable resources. In this work, Fe-loaded montmorillonite/TiO2 composite (Fe-Mt/TiO2), pure TiO2, Mt/TiO2 and Mt/Fe-TiO2 were fabricated and further utilized as photocatalysts for the production of formic acid from glucose under visible-light irradiation. Among the as-prepared composites, the Fe-Mt/TiO2 exhibited the highest glucose conversion (83%), formic acid production (44%) and formic acid selectivity (53%). The effective heterojunction between Fe-Mt and TiO2 is proposed to describe the superior photocatalytic activity of Fe-Mt/TiO2, which effectively suppressed the recombination of the photogenerated electrons and holes during the reaction. Mechanism investigations suggested that the selective photocatalytic oxidation of glucose into formic acid by Fe-Mt/TiO2 mainly occurred through an alpha-scission reaction pathway, driven by the main active species as O-center dot(2)- and O-1(2). The research findings in this work suggested that the Fe-Mt/TiO2 composite can be applied as a low-cost, easy-to-prepare, reusable and selective photocatalyst for sustainable synthesis of high-value chemicals from biomass-derived substrates.