Fabrication of some Quaternary Spinel Structure Electrodes for Photoelectrochemical Applications.

Abstract

In this study, nanostructured ZnNiCo2O4 and MnNiCo2O4 electrodes were fabricated by spray pyrolysis method and annealed at 550oC for 2 h. The structural, optical, and Photoelectrochemical properties were studied. The structural properties were examined using X-ray diffraction (XRD). The results show that the samples have cubic spinel structure. The atomic percentage determined by (EDX) and the thickness (cross section) of films measured by (FE-SEM), as well as the surface roughness measured through (AFM) are all used for analysis. The optical properties were investigated by UV-visible spectrophotometer, the energy band gaps of ZnNiCo2O4 and MnNiCo2O4 were estimated to be approximately 2.2 and 2.4 eV respectively. The photoelectrochemical, comprising of photocurrent density, linear sweep voltammograms (LSV) and Mott-Schottky (MS), displayed flat band values of (1.5 eV and -0.55 eV) Vs NHE for ZnNiCo2O4 and MnNiCo2O4 respectively, where the conduction band and valance band values of ZnNiCo2O4 were (C. B= -0.6 eV and V.B= 1.6 eV ), while those of MnNiCo2O4 were (C.B= -0.65 eV and V.B= 1.75 eV ). The corresponding photocurrent densities for ZnNiCo2O4 and MnNiCo2O4 were 35 µA/cm2 and 50 µA/cm2, respectively. The electrodes were comprehensively studied for ZnNiCo2O4 and MnNiCo2O4 under a neutral water condition.

Keywords

• Photoelectrochemical, Transition Metal Oxides, Photocatalytic, Spinel Structure.