Significant Enhancement of Photoactivity in Hybrid TiO 2 /g-C 3 N 4 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/Ti02). 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.