TiO2:Cu-modified g-C3N4 nanocomposites for photocatalysis and energy storage applications

In this work, g- :Cu nanocomposites were synthesized via a cost-effective sol–gel strategy, enabling the in situ growth of TiO 2 :Cu nanoparticles on exfoliated g-C 3 N 4 nanosheets. The structural, morphological, and optical characteristics were systematically investigated using XRD, FTIR, EPR, TEM-SEM, PL, UV–Vis, surface area and porosity measurements, as well as XPS spectroscopy. The formation of a well-defined g- heterojunction, combined with Cu-induced defect states, promotes efficient charge separation and enhanced interfacial charge transfer. As a result, the g- :Cu (1%) photocatalyst exhibits superior activity, achieving 70% pollutant removal after 5 h of irradiation. In parallel, electrochemical measurements demonstrate that the g- :Cu 3% electrode delivers the highest specific capacitance of 168.83 F/g, energy density of 23.03 Wh/kg and power density of 1658 W/kg, highlighting the beneficial role of optimized Cu doping in facilitating ion/electron transport. The improved multifunctional performance is attributed to the synergistic interaction between the heterojunction interface and Cu-induced electronic modulation. These findings provide insight into the structure–property-performance relationships governing hybrid photocatalytic-electrochemical materials and highlight the potential of Cu-modified g- nanostructures for sustainable environmental and energy-related applications.