Boosting the visible-light photoactivities of BiVO4 nanoplates by Eu doping and coupling CeOx nanoparticles for CO2 reduction and organic oxidation

Comprehensively extending the visible light response, enhancing charge separation and promoting surface catalysis of rationally designed photocatalysts are highly desired for improving visible-light activity. For this, CeOx coupled Eu3+ doped BiVO4 nanoplates (NPs) have been prepared by first synthesizing Eu3+ doped BiVO4 nanoplates via a hydrothermal route and then coupling CeOx nanoparticles through a wet-chemical method. In contrast to the photocatalytic and photo-degradative performance of BiVO4, it is observed that the amount-optimized CeOx/BiVO4:Eu3+ nanoparticles possess ∼3-time enhancement in visible-light photocatalytic performance for CO2 conversion to CH4 and degradation of 2,4-dichlorophenol (2,4-DCP). According to the results obtained from XPS, produced ˙OH amount measurements, surface photovoltage response (SPS) and transient photoluminescence spectroscopy (PL), the promoted visible-light photoactivities of CeOx/BiVO4:Eu3+ NPs are caused by the combination of the extended visible-light absorption by Eu3+ doping and enhanced charge separation by coupling CeOx and absorbing excited high level photoelectrons from BiVO4. In addition, raising the valence band extends visible light utilization which consequently increases the production of high-level energy electrons. Moreover, it is confirmed from CO2-TPD and electrochemical CO2 reduction that the high photoactivities are also ascribed to the enhanced surface adsorption of CO2 and catalytic ability of coupled CeOx.