Dual‐Functional and Low‐Toxicity ZnO Nanoparticles From Pomegranate Peel: Impact of Synthesis Parameters on Photocatalytic and Supercapacitive Performance

The development of eco‐efficient multifunctional nanomaterials is crucial for environmental remediation and energy storage. This study systematically investigated the impact of synthesis temperature (25°C vs. 80°C) and zinc acetate concentration (0.5–2 M) on pomegranate peel extract‐mediated ZnO nanoparticles. Physicochemical characterization revealed that ambient synthesis (25°C) at 2 M (sample A2) produced an interconnected hierarchical architecture with a specific surface area (SSA BET ) of 12.1 m 2 /g, a zeta potential of −28.6 mV, and a narrow bandgap of 2.744 eV. Consequently, A2 exhibited superior bifunctional performance, achieving a photocatalytic rate constant ( k app ) of 0.065 min −1 for the degradation of Methylene Blue (10 ppm) and a specific capacitance of 208 F g −1 at 1 A g −1 . Crucially, electrochemical impedance spectroscopy confirmed that the interconnected framework of A2 provided a negligible charge–transfer resistance ( R p = 0.0043 Ω), facilitating efficient charge transport compared to the resistive, fragmented morphologies produced at 80°C ( R p = 3069.64 Ω). Furthermore, A2 demonstrated low acute ecotoxicity toward Artemia salina (LC 50 = 4842 μg/mL). These findings provide a data‐driven framework for the low‐energy synthesis of high‐performance, sustainable ZnO nanomaterials.