Comparative Study on the Effects of Surface Area, Conduction Band and Valence Band Positions on the Photocatalytic Activity of ZnO-M x O y Heterostructures

Abstract

ZnO-MxOy heterostructures (M=Co, Mn, Ni, or In) are fabricated via hydrothermal synthesis method. X-ray diffraction and Fourier-transform infrared spectroscopy analyses endorse the successive formation of the various heterostructures. Field Emission Scanning electron microscope and Brunauer-Emmett-Teller (BET) surface area studies confirm the porous nature of the heterostructures obtained. The band gaps of various heterostructures are calculated that, 3.1, 2.71, 2.64, and 2.19 eV for ZnO-NiO, ZnO-In2O3, ZnO-Co3O4, and ZnO-MnO2, respectively. The photocatalytic activities of the fabricated heterostructures are investigated through the degradation of phenol under direct sunlight irradiation. The results show that the photocatalytic activity is affected by the conduction band (CB) and valence band (VB) positions rather than surface area of ZnO-MxOy heterostructure nanocomposites.