Metal-fluorine bonds promote photoelectrochemical CH3OH oxidation to HCHO on BiVO4 photoanode

 As an important downstream product of CH₃OH, HCHO is also an important chemical raw material, which is used in important applications in textile, chemical and medical fields. Bulk photoanodes face the dual challenges of low efficiency and poor selectivity in the photoelectrochemical oxidation of CH₃OH to HCHO. Modifying the BiVO₄ photoanode with highly electronegative fluoride ions to optimize its surface electronic structure is expected to significantly improve its performance for this reaction.

Recently, a research team led by Prof. Hongwei Huang from China University of Geosciences (Beijing) developed a surface-fluorinated BiVO₄ photoanode that selectively oxidizes CH₃OH to HCHO in a near-neutral electrolyte. The fluorinated photoanode showed enhanced adsorption and activation of CH₃OH molecules, and the formed V–F bond promoted O–H fracture. Finally, the fluorinated photoanode showed excellent PEC performance for the preparation of HCHO from CH₃OH oxidation in near–neutral electrolyte. The results were published in Chinese Journal of Catalysis (DOI:10.1016/S1872-2067(25)64831-5).

The BiVO₄ photoanode with fluorinated surface was prepared by a facile surface fluorination treatment and the optimal sample achieved a Faraday efficiency of 90.7% for CH₃OH oxidation into HCHO with accumulated 98.12 µmol HCHO within 5 hours at 0.8 VRHE in near-neutral electrolyte. The position and role of F in the photoanode were proved through a series of characterizations and DFT theoretical calculations.

The characterization of the surface morphology and electronic structure of the fluorinated BiVO₄ photoanode showed that the highly electronegative fluorine ion replaces the oxygen on the surface of the BiVO₄ photoanode to form the metal–fluorine bond. On this basis, a theoretical calculation model was established, and the results of theoretical calculation proved that the fluorinated photoanode showed enhanced adsorption and activation of CH₃OH molecules, and the formed V–F bond promoted O–H fracture. At the same time, surface fluorination also promoted the activation of the key C–H bond in the oxidation process of CH₃OH and the desorption of HCHO.

About the journal

Chinese Journal of Catalysis is co-sponsored by Dalian Institute of Chemical Physics, Chinese Academy of Sciences and Chinese Chemical Society, and it is currently published by Elsevier group. This monthly journal publishes in English timely contributions of original and rigorously reviewed manuscripts covering all areas of catalysis. The journal publishes Reviews, Accounts, Communications, Articles, Highlights, Perspectives, and Viewpoints of highly scientific values that help understanding and defining of new concepts in both fundamental issues and practical applications of catalysis. Chinese Journal of Catalysis ranks among the top six journals in Applied Chemistry with a current SCI impact factor of 17.7. The Editors-in-Chief are Profs. Can Li and Tao Zhang.

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