Plant-Mediated Synthesis of TiO₂–ZnO Nanocomposites Using Nigella sativa Seeds for Solar Energy Applications

The present study introduces a novel and environmentally sustainable approach to synthesizing TiO₂–ZnO nanocomposites using Nigella sativa seed extract, which has not been previously reported in the context of solar cell applications. This green synthesis technique uses the natural phytochemicals found in Nigella sativa seeds as stabilizing and reducing agents, in contrast to traditional chemical synthesis methods that frequently use hazardous chemicals and energy-intensive procedures. These bioactive compounds not only promote the formation of nanocomposites but also aid in functionalizing their surface, thereby enhancing their chemical stability and charge transfer properties. Furthermore, the incorporation of both TiO₂ and ZnO in a heterostructured nanocomposite is particularly advantageous, as it combines the high photoactivity of TiO₂ with the excellent electron mobility of ZnO. This synergistic effect leads to improved light absorption, reduced electron-hole recombination, and enhanced charge transport key factors in the performance of solar cells. The study stands out by integrating material synthesis, phytochemical surface modification, and optoelectronic property evaluation, including UV–Visible spectrographic analysis, cyclic voltammetry (CV) and current–voltage (I–V) analysis. These findings highlight the significant potential of Nigella sativa-mediated TiO₂–ZnO nanocomposites as cost-effective, eco-friendly, and high-performance materials for next-generation photovoltaic devices.