Effective Visible-Excited Charge Separation in Silicate-Bridged ZnO/BiVO4 Nanocomposite and Its Contribution to Enhanced Photocatalytic Activity

It is highly desired to enhance the visible-excited charge separation of nanosized BiVO4 for utilization in photocatalysis. Here ZnO/BiVO4 nanocomposites in different molar-ratios are fabricated by simple wet-chemical processes, after synthesis of nanosized BiVO4 and ZnO by hydrothermal methods. It is shown by means of atmosphere-controlled steady-state surface photovoltage spectra and transient-state surface photovoltage responses that the photogenerated charges of resulting nanocomposite shows longer lifetime and higher separation than that of BiVO4 alone. This leads to its superior photoactivities for water oxidation to produce O2 and for colorless pollutant degradation under visible irradiation, with about three times enhancement. Interestingly, it is suggested that the prolonged lifetime and enhanced separation of photogenerated charges in the nanocomposite is attributed to the unusual spatial transfer of visible-excited high-energy electrons, by visible radiation from BiVO4 to ZnO on the basis of th...