2D/2D Co-Al layered double hydroxide/TiO2 heterostructures for photoreduction of Cr (VI)

Abstract

Co-Al layered double hydroxide (LDH)/TiO2heterostructures were synthesized using TiO2 nanobelts by a solvothermal method. X-ray diffraction analysis and morphology observation indicate that layered Co-Al LDH was grown on TiO2nanobelts consisted of anatase and TiO2(B). The phase composition of TiO2nanobelt samples depended on the calcined temperature. The phase composition of TiO2 affected the adsorption ability of composite samples. The pseudo-second-order kinetics model fits for the Cr(VI) ions adsorption kinetics of LDH/TiO2 composite samples. In the case of dark condition, the Cr(VI) removal using composite sample (LT4) was about 45%.In contrast, the Cr(VI) removal of the sample reached up to 100% within 10 min under full solar spectrum irradiation. The excellent performance of the sample can be ascribed to the formation of CoAl-LDH/TiO2 heterostructures consisted of one-dimensional TiO2 nanostructure with mixed anatase and TiO2(B) phases and optimized LDH loading. This heterostructure revealed relatively high stability. The interface of two phases effectively hinders the recombination of photo-generated carriers. In addition, the presence of uniformly distributed CoAl-LDH improved the conductivity and light absorption of the composite sample.