Efficient removal of Cr(VI) by a 3D Z-scheme TiO2-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 (lambda) > 420 nm) the removal rate of Cr(VI) almost reached 100%, which is much better than the performance of pristine TiO2 and Zn0.5Cd0.5S, 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 TiO2 and Zn0.5Cd0.5S 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. (C) 2022 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.

Automated summary

This article reports a TiO2-ZnxCd1-xS graphene aerogel (TSGA) photocatalyst with high efficiency and stability for the removal of pollutants from water. The TSGA exhibited excellent performance in adsorption and visible light photocatalysis for the removal of Cr(VI), with a high removal rate reached after a short irradiation time. The TSGA also showed good stability and reusability, making it a promising candidate for efficient and sustainable heavy metal removal from polluted aqueous environments.