Significant Enhancement of Photoactivity in Hybrid TiO₂/g‑C₃N₄ Nanorod Catalysts Modified with Cu–Ni-Based Nanostructures

Light-driven processes such as photocatalytic environmental remediation and photoelectrochemical (PEC) water splitting to produce hydrogen under sunlight are key technologies toward energy sustainability. Despite enormous efforts, a suitable photocatalyst fulfilling all the main requirements such as high photoactivity under visible light, chemical stability, environmental friendliness, and low cost has not been found yet. A promising approach to overcome these limitations is to use hybrid nanostructures showing improved activity and physicochemical properties when compared with single components. Herein, we present a novel photocatalytic nanocomposite system based on titania (TiO₂): titania nanorod wrapped with Ni­(OH)₂ and Cu­(OH)₂ composite carbon nitride (CuNi@g-C₃N₄/TiO₂). This carefully tuned photoanode nanostructure shows almost one order of magnitude higher photocurrent density compared to unsensitized TiO₂ nanorods for PEC water splitting upon solar-light illumination. The heterostructured g-C₃N₄ strongly improves visible absorption of light, separation of electrons and holes, and surface catalysis due to the effect of Cu­(OH)₂ nanoparticles and Ni­(OH)₂ nanosheets, respectively. The improved photoperformance ascribed to the integrative cooperation effect of all the counterparts resulting in a one-dimensional hydrid nanostructured photoanode with improved light absorption, facile charge separation, and efficient surface catalysis toward PEC oxygen evolution