Photocatalytic properties of mesoporous alumina containing Ni doped CdS nanostructures

Abstract

A stable and visible light responsive photocatalyst, Ni doped CdS dispersed on mesoporous Al2O3, exhibits enhanced photocatalytic activity for methyl orange (MO) degradation compared to CdS-Al2O3, CdS and Ni doped CdS. A significant adsorption of MO is observed in mesoporous alumina and the composite. Solid state MAS NMR studies suggest a strong interaction between CdS and Al2O3 in this new combination of heterostructured photocatalyst. This interaction between CdS and Al2O3 helps in a good dispersion of CdS on alumina, which in turn enhances the photocatalytic activity. In the composite, CdS shows wurtzite type structure where as Al2O3 (γ-Al2O3) shows cubic spinel structure. Ni doped CdS-Al2O3 nanocomposite shows improved visible light absorption compared to undoped CdS. Photoelectrochemical studies suggest that better separation of charge carriers occurs in 1Ni-CdS and 1Ni-85CA compared to CdS. The enhanced activity of Ni doped composite nanostructure is attributed to increased adsorption of MO in the composite, increased surface area, better separation of photogenerated charge carriers and improved visible light absorption. Total organic carbon analysis of the dye solution after irradiation indicates the mineralization of the dye during photocatalytic reaction. Photodegradation in the presence of different quenchers suggests that e− plays a significant role in the degradation of methyl orange.