CuO@CdO/MgO Nanocomposites: Composition‐Driven Photocatalysis, Energy Storage, and Biocompatibility

A series of CuO@CdO/MgO ternary nanocomposites with variable CuO and CdO concentrations (10%, 20%, and 30%) in an MgO matrix were synthesized using a one‐step coprecipitation‐hydrothermal technique. The aim of this research is to create and test multifunctional CuO@CdO/MgO nanocomposites with varying structural, optical, electrochemical, and biological properties. By altering the CuO and CdO ratios, the composites improve their photocatalytic potential, energy storage capability, and biocompatibility. The effects of composition on crystallinity, morphology, band gap, photoluminescence, redox behavior, and cytocompatibility were thoroughly investigated. Cyclical voltammetry demonstrated increased capacitance and redox activity, particularly in the 30% sample. MTT experiments demonstrated concentration‐dependent biocompatibility, with no significant cytotoxicity found for 10% and 20% samples at 50 µg/mL after 24–48 h of incubation.