Photocatalysis on silver-layer silicate/titanium dioxide composite thin films at solid/vapour interface

Silver-montmorillonite/TiO2 composites were prepared using various mixing ratios. The optical properties of the catalyst composites were evaluated DR-UV–vis spectrophotometry. Their photocatalytic efficiencies were tested in the degradation of ethanol vapour at a relative humidity of ∼70% in a closed circulating reactor. Light sources used were 15 W lamps, one rich in UV (λ ≥ 254 nm) and one emitting visible light (λ ≥ 435 nm). The course of photodegradation of ethanol vapour was monitored by gas chromatography. By incorporating silver ions into clay minerals/TiO2 mixtures with different ratio, we obtained composites capable of degrading ethanol in the visible wavelength range about twice as fast as the reference photocatalyst, type P25. The synergistic effect is interpreted as the result of the excellent adsorption capabilities of layer silicates combined with the advantageous effect of silver nanoparticles and silver oxides on light absorption in the visible range.