Visible Light-Active Copper Cobaltite Supported Film for Hexavalent Chromium Photocatalytic Reduction

Copper cobaltite (CuCo₂O₄) films were synthesized on titanium dioxide (TiO₂) and on fluorine-doped tin oxide (FTO) substrates using a hydrothermal method and characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), diffuse reflectance spectroscopy (DRS), and cyclic voltammetry. This research addresses the challenge of hexavalent chromium (Cr(VI)) pollution by employing CuCo₂O₄/TiO₂/FTO as visible light-active photocatalyst. The films demonstrated strong absorption in the visible spectrum. The heterostructure comprising CuCo₂O₄ and TiO₂ films was synthesized to enhance the photocatalytic reduction of Cr(VI) through synergetic effects. The CuCo₂O₄/TiO₂/FTO film exhibited superior photoreduction performance, achieving photoreduction efficiencies of ∼62.9% under UV-A and ∼72.3% under visible light, outperforming individual TiO₂/FTO and CuCo₂O₄/FTO films. Reaction rates were 0.00433 min⁻¹ (R2: 0.98893) under UV and 0.00638 min−1 (R2: 0.98787) under visible light, with a half-life of 1.81 h, indicating significant improvement in photocatalytic activity. However, it is necessary to optimize the synthesis parameters to analyze their impact on its physicochemical properties and its behavior as a photocatalyst. Making possible its applicability is due to the appropriate charge transport, visible light absorption, reduced recombination of electron-holes pairs, and improved photocatalytic performance.