NiO-ZnO heterostructure with photocatalytic activity

The NiO-ZnO heterostructures were fabricated using a combination of physical vapour deposition and thermal oxidation techniques. Thin films of nickel and zinc were sequentially deposited onto non-conductive substrates and subsequently oxidised to form nanostructured p–n junctions. The influence of thermal oxidation parameters on the structural, morphological, and optical properties of the resulting heterostructures was thoroughly investigated using scanning electron microscopy, high-resolution transmission microscopy, X-ray diffraction, and UV-Vis spectroscopy. The heterostructures exhibited a strong UV absorption and a band gap of 3.29 eV. Photocatalytic activity was evaluated using an aqueous solution of methylene blue under UV irradiation. The NiO-ZnO films achieved a degradation efficiency of 93% after 540 min, confirming their potential for photocatalytic water treatment applications. These preliminary findings demonstrate that even thin-film configurations with limited catalyst mass can be promising in degrading organic pollutants.