TwoBirds with One Stone Strategy: Simultaneous Removalof Cr(VI) and Cr(III) Efficiently by Porous ZnIn₂S₄/SBA-15 Nanorods

Carcinogen Cr(VI) is reduced efficiently into Cr(III) by a photocatalyst, but the produced Cr(III) is difficult to transfer from the photocatalytic active site. The “two birds with one stone” strategy is proposed to realize the in situ growth of ZnIn₂S₄ nanoplates on SBA-15 and the creation of separated active sites, in which ZnO loading on the porous SBA-15 nanorod was used as a zinc source. Obtained samples ZnIn₂S₄/SBA-15 (ZIS/SBA) showed the redshift of the absorption band and better separation of photoinduced carriers than pristine ZnIn₂S₄, due to its smaller size and S defect. All of the Cr(VI) was reduced to Cr(III) by the ZIS/SBA sample during the photocatalytic process, which was 2 times higher than pristine ZnIn₂S₄. Moreover, 92.8% of Cr(III) was adsorbed simultaneously during photocatalysis due to the electrostatic interaction from SBA-15. In addition, the ZIS/SBA sample showed good recycling stability after 5 times cycles, providing a new strategy for the in situ growth of ZnIn₂S₄ on the surface of porous materials and a novel way for the simultaneous removal of Cr(VI) and Cr(III) during photocatalysis.