Highly selective photocatalytic oxidation of 5-hydroxymethylfurfural by interfacial Pt–O bonding Pt–Ov–BiOBr

Abstract

The photocatalytic oxidation of 5-hydroxymethylfurfural (HMF) has the advantages of mild conditions and a controllable oxidation degree. There are a number of methods to increase its reactivity by boosting the production of ˙O₂⁻, among which using metal-modified semiconductor catalyst systems is one of the most promising methods. Although several metal-modified semiconductor catalyst systems have been successfully designed, only a small number of them have been used in photocatalytic selective oxidation, and the contact interface between the metal and semiconductor catalysts has not been well studied. Here, interfacial Pt–O bonded Pt–Ov–BiOBr catalysts were designed for photocatalytic HMF selective oxidation. Due to the environment of unsaturated coordination on Ov–BiOBr, Pt can form a Pt–O bond as an electron transport channel to transfer photogenerated electrons from Ov–BiOBr to Pt for efficient generation of ˙O₂⁻. Meanwhile, photogenerated h⁺ will gather at the interface between Pt and Ov–BiOBr contact to oxidize HMF to carbon-centered radicals. The spatial proximity of the ˙O₂⁻ and carbon-centered radicals at the Pt–Ov–BiOBr contact interface promotes reciprocal collisions and consequently reactions. Additionally, Pt–Ov–BiOBr was found to have excellent photogenerated electron–hole separation efficiency by photoelectric characterization, and the ESR and O₂-TPD results showed that Pt can activate oxygen more effectively to produce ˙O₂⁻. As a result, the conversion rate of HMF selective oxidation of Pt–Ov–BiOBr becomes 4.6 times higher and the selectivity becomes 2.2 times higher compared to those of BiOBr. This study suggests that an appropriately designed metal–semiconductor contact interface can boost the effectiveness of HMF photocatalytic selective oxidation.