All-solid-state Z-scheme plasmonic Si@Au nanoparticles on CuBi2O4/BiVO4 for efficient photocatalytic activity

Development of plasmon-mediated catalysis emerged as an attractive alternative to propel chemical reactions. Novel plasmonic material in the form of Si@Au as core@shell nanostructure was experimentally synthesized with good colloidal stability. The Si@Au showed broad tunable light absorption spectra which benefits an effective light harvesting. The observed gold nanoparticles have narrow particle size distribution of 5 nm with lattice fringe of 1.23 Å corresponding to {3 1 1} gold lattice spacing. Whereas the silicon nanoparticles emitted photoluminescence under ultraviolet light irradiation, indicating successful alteration towards direct bandgap by quantum confinement effect in zero-dimensional structure. The Si@Au nanostructures were confirmed using high-resolution transmission electron microscopy and selected area electron diffraction, with the obtained localized surface plasmon resonance spectrum conformed to the simulated pattern corresponding to core@shell structure with a 5 nm-thin-shell Au layer. The vanishing photoluminescence in Si@Au nanostructure suggested suppression of the charge recombination, meaning that photogenerated charge carrier could be preferably used for photocatalytic reactions. The presence of novel Si@Au did not only show broad absorption spectra which is useful for effective light harvesting, but also acted as solid-state mediator driving the photocarrier transfer mode into Z-scheme system. As the result, an enhanced phenol degradation can be achieved, as indicated by 95% phenol degradation under visible light irradiation within 3 h.