Some physical investigations on NiCo2O4 thin films for potential applications

This paper covers a successful growth of nickel cobaltite oxide (NiCo2O4) thin films deposited on glass substrates at 450 degrees C and treated at 500 degrees C in air. The prepared samples were investigated by various spectroscopy techniques. First, X-ray diffractogram revealed that all films crystallized in cubic spinel structure with an intense and sharp diffraction peak corresponding to (311) plane. Raman spectra contain four peaks located at about 188, 477, 527 and 670 cm(-1) originated from the F-2g, E-g, F-2g and A(1g) vibrational modes of NiCo2O4 spinel material, respectively. Second, the optical measurements by depicting the presence of two band gap energies are observed at 1.49 eV and 2.77 eV for annealed sample, respectively. Photoluminescence measurements showed broad peaks in the range of 720-780 nm identified mainly due to defect states. Moreover, the electro-pyroelectric study of these films has been carried out and discussed. Finally, the photocatalytic activity of prepared NiCo2O4 thin film was evaluated for degradation of MB dye which demonstrated 96% degradation rate after 120 min under visible illumination for annealed samples and a mechanism of degradation is indeed proposed.