New Fe-doped two-dimensional BiVO4 nanosheets for direct methane conversion to methyl oxygenates

Abstract

Photocatalytic methane conversion is a sustainable approach to transform methane under mild conditions into its value-added derivatives for the petrochemical industry. However, obtaining high productivity and selectivity of desired products still remains a great challenge. In this work, high-efficiency Fe-doped two-dimensional BiVO₄ nanosheets have been synthesized and evaluated for photocatalytic methane conversion with H₂O, O₂ or H₂O₂ as the oxidizer. The Fe-doped and undoped samples were obtained by hydrothermal synthesis using 3-dodecylbenzenesulfonate (SDBS) as the morphology-directing agent, and examined by XRD, SEM, EDS, TEM, XPS, UV-DRS and BET characterization techniques. The replacement of some Bi³⁺ with Fe³⁺ was a successful approach to enhance the photoexcitation process and the adsorption properties of BiVO₄, resulting in an improvement in the yield of methyl oxygenates. Complete selectivity of methyl oxygenates (CH₃OH and CH₃OOH) was achieved, and the yield reached 217.6 μmol g_cat⁻¹ h⁻¹ in 2 h under visible light irradiation under mild conditions over 1.0 wt% Fe-doped BiVO₄ nanosheets in the presence of H₂O₂, outperforming most reported studies on this reaction. This work provides new insight into the choice of a suitable oxidizer for methane conversion in the BiVO₄ photocatalyst system by projecting H₂O₂ as the relevant oxidant.