Enhancing the Photocatalytic Activity of BiVO₄ for Oxygen Evolution by Ce Doping: Ce³⁺ Ions as Hole Traps

To enhance the photocatalytic activity of monoclinic BiVO₄ for O₂ evolution from water, Ce-doped BiVO₄ was prepared using the one-pot facile solvothermal method and characterized via XRD, Raman, XPS, and electrochemical impedance spectroscopy (EIS). The XPS spectra confirm that Ce component is Ce³⁺ ions instead of Ce⁴⁺ ions. From the structural characterization and the calculations of formation energies it has been stated that the doping of Ce³⁺ ions takes place at Bi³⁺ sites without changing the host structure. The as-prepared Ce-doped BiVO₄ samples display significantly enhanced photocatalytic O₂ evolution activities from water compared to pristine BiVO₄. Density of states calculations indicate that Ce³⁺ ions act as hole traps, thereby delaying the recombination of photogenerated electrons and holes. The results demonstrate that the substitution of the remaining monoclinic crystal structure may offer an attractive alternative approach for the doping of BiVO₄ to enhance the evolution activity of photocatalytic O₂.