In fact, the lower PL intensity refers to the higher separation and the lower recombination rates of the photogenerated electron-hole pairs. The PL intensities of BiVO4/WO3 around the distinctive NBE peaks are less pronounced compared to those of the pristine WO3 and BiVO4, suggesting an effectively diminished charge recombination due to the heterojunction formation between these two metal oxides. Moreover, the PL intensity of all observed emission peaks was further decreased in the spectrum of the Au/BiVO4/WO3, accelerating the charge separation, as discussed in Figure . for BiVO4 and WO3 were -0.243 and -0.213 V vs. Ag/AgCl, respectively. In n-type semiconductors, the energy difference between the conduction band (CB) edge and Vfb is typically very small (~0.1 eV) . Consequently, the CB edge of BiVO4 is slightly more negative than that of WO3, which is in line with previously published results . The heterostructure between BiVO4 and WO3 should therefore enable an effective extraction of the photogenerated electrons from the CB of the BiVO4 to the CB of WO3, resulting in an increased PEC performance of BiVO4/WO3.