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

• Co-Al LDH modified TiO 2 nanobelts were synthesized by a two-step solvothermal method. • A considerable effect of Cr(VI) removal is dual adsorption-photocatalytic mechanism. • Excellent performance is ascribed to the mixed-phase TiO 2 one-dimensional nanostructure. • The uniformly grown LDH improves the conductivity and light absorption of the sample. Co-Al layered double hydroxide (LDH)/TiO 2 heterostructures were synthesized using TiO 2 nanobelts by a solvothermal method. X-ray diffraction analysis and morphology observation indicate that layered Co-Al LDH was grown on TiO 2 nanobelts consisted of anatase and TiO 2 (B). The phase composition of TiO 2 nanobelt samples depended on the calcined temperature. The phase composition of TiO 2 affected the adsorption ability of composite samples. The pseudo-second-order kinetics model fits for the Cr(VI) ions adsorption kinetics of LDH/TiO 2 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/TiO 2 heterostructures consisted of one-dimensional TiO 2 nanostructure with mixed anatase and TiO 2 (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.