Abstract
The incorporation of Ag nanoparticles onto BiVO4 (a known H2O oxidising photocatalyst) through magnetron sputtering to form a composite was studied. ICP-OES results showed that the loading of Ag on BiVO4 was below 1% in all cases. UV-Vis DRS and CO2-TPD analyses demonstrated that upon incorporation of Ag onto BiVO4, an increase in the extent of visible light absorption and CO2 adsorption was seen. TEM imaging showed the presence of Ag particles on the surface of larger BiVO4 particles, while XRD analysis provided evidence for some doping of Ag into BiVO4 lattices. The effect of the composite formation on the activity of the materials in the artificial photosynthesis reaction was significant. BiVO4 alone produces negligible amounts of gaseous products. However, the Ag-sputtered composites produce both CO and CH4, with a higher loading of Ag leading to higher levels of product formation. This reactivity is ascribed to the generation of a heterojunction in the composite material. It is suggested that the generation of holes in BiVO4 following photon absorption is used to provide protons (from H2O oxidation), and the decay of an SPR response on the Ag NPs provides hot electrons, which together with the protons reduce CO2 to produce CH4, CO, and adsorbed hydrocarbonaceous species.
Published Version
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