Strong metal-support interaction induced by Pt-O-Bi bonding in mesoporous anatase TiO2 for base-free catalytic biomass valorisation

The exceptional catalytic activity of bimetallic or trimetallic catalysts has been demonstrated in various reactions. However, in-depth understanding of the intricate metal-support interactions remains crucial yet challenging. Herein, a well-defined, highly active, Pt single-atom dominant Pt-Bi/TiO2 catalyst with mesoporous crystalline anatase structure was fabricated via an in situ one-pot evaporation-induced self-assembly method and employed for the base-free oxidation of biomass-derived 5-hydroxymethylfurfural (HMF) to value-added chemicals in aqueous media. Our findings demonstrate that Bi incorporation not only greatly reinforces the strong metal-support interaction between Pt and the support, but also benefits the Pt distribution, enabling the formation of single-atom Pt-O-Bi bonding, characterized by high-angle annular dark-field scanning transmission electron microscopy, X-ray photoelectron spectroscopy, carbon monoxide diffuse reflectance infrared Fourier transform spectroscopy and X-ray absorption spectroscopy analysis. Additionally, Bi incorporation results in remarkable increases in the catalyst's surface area and concentration of surface oxygen vacancies compared to the Pt/TiO2 counterpart. The changes in both geometric and electronic structures of the catalyst induced by Bi incorporation effectively reduce the dissociation energy of O2 into active oxygen species, the adsorption energy of HMF, as well as the activation barrier for its conversion to 2,5-diformylfuran, ultimately resulting in a significant enhancement in the conversion rate of HMF. These findings provide valuable insights into the rational design of efficient catalysts for biomass valorization.