Efficient removal of Cr(Ⅵ) by a 3D Z-scheme TiO_(2)-ZnxCd1-xS graphene aerogel via synergy of adsorption and photocatalysis under visible light

Efficient and robust photocatalysts for environmental pollutants removal with outstanding stability have great significance.Herein,we report a kind of three dimensional(3D)photocatalyst presented as Z-scheme heterojunction,which combining TiO_(2) and ZnxCd1-xS with graphene aerogel to contrast TiO2-ZnxCd1-xS graphene aerogel(TSGA,x=0.5)through a moderate hydrothermal process.The as-prepared Z-scheme TSGA was used to remove aqueous Cr(VI)via a synergistic effect of adsorption and visible light photocatalysis.The adsorption equilibrium can be reached about 40 min,then after about 30 min irradiation under visible light(wavelength(λ)>420 nm)the removal rate of Cr(VI)almost reached 100%,which is much better than the performance of pristine TiO_(2) and Zn_(0.5)Cd_(0.5)S,as well as TiO2 graphene aerogel(TGA)and Zn0.5Cd0.5S graphene aerogel(SGA).The virulent Cr(VI)was reduced to Cr(III)with hypotoxicity after photocatalysis on TSGA,meanwhile the as-synthesized TSGA presented a good stability and reusability.The reduced graphene oxide(rGO)sheets between TiO_(2) and Zn_(0.5)Cd_(0.5)S played a role as charge transfer mediator,promoting the photoinduced electrons transfer and photocatalysis ability of TSGA was enhanced significantly.Hence,such photocatalyst exhibits a potential application on removing heavy metals with high efficiency and stability from polluted aqueous environment.