Fluorination of the WO₃ Photoanode to Promote Interfacial Charge Transfer for Efficient Photoelectrocatalytic Performances

Click to copy article linkArticle link copied!

To improve the interfacial charge transfer over a tungsten oxide (WO₃) photoanode for an efficient photoelectrocatalytic (PEC) process, WO₃ was fluorinated in a solvothermal process in the presence of NH₄F. It was shown that, after the fluorination with the molar ratio of NH₄F to WO₃ at 0.4, the charge separation and charge injection efficiencies increased from 22.02 to 61.15% at 0.5 V vs Ag/AgCl and from 44.71 to 72.69% at 0.5 V vs Ag/AgCl, respectively, significantly enhancing the PEC performances for synergetic tetracycline degradation and H₂ evolution. Various characterization and density functional theory calculation results revealed that the incorporation of fluorine into the WO₃ lattice by fluorination substantially raises the Fermi level of WO₃, which bends the energy bands of WO₃ more upward at the semiconductor/electrolyte interface. The intensified upward bending bands effectively promote charge transfer at the fluorinated WO₃ photoanode/electrolyte interface, achieving the observed efficient PEC performances.