Synthesis of SPR Au/BiVO4 quantum dot/rutile-TiO2 nanorod array composites as efficient visible-light photocatalysts to convert CO2 and mechanism insight

It is highly desired to develop efficient visible-light-driven BiVO4-based nano-photocatalysts with recyclable feature by modulating photogenerated electrons and extending visible-light responses. Herein, a novel nanocomposite array has been successfully fabricated by uniformly decorating BiVO4 quantum dot (BiVO4-QD) with an average size of ∼5 nm onto rutile-TiO2 nanorod array (RTA) through the successive ionic layer adsorption and reaction processes, and exhibited high photocatalytic activity for converting CO2 to CO and CH4 under visible-light irradiation. The exceptional photoactivity is mainly attributed to the greatly-enhanced charge separation and prolonged charge lifetime by effectively transferring photogenerated electrons at the elevated conduction band bottom of BiVO4 to rutile-TiO2 nanorods as favorable electron acceptors and transport mediums by means of surface photovoltage technique, Mott-Schottky analyses and EIS measurements. Moreover, the photoactivity of optimized BiVO4-QD/RTA nanocomposite is further improved after loading SPR Au nanoparticles by promoting charge separation and extending visible-light responses, about 6.5-time higher than that of BiVO4-QD decorated anatase nanoparticle film. This work provides a feasible strategy to prepare easily reused and efficient BiVO4-based photocatalyst, which is also applicable to other semiconductors with low CB.