Microwave‐Assisted Green Synthesis of CuO Nanoparticles Using <i>Myrciaria Dubia</i> Extract for Efficient Solar‐Light‐Driven Photocatalytic Degradation of Methylene Blue

ABSTRACT This study reports a microwave‐assisted biogenic route for synthesizing CuO nanoparticles using Myrciaria dubia (camu camu) fruit extract under three microwave power–time programs: 700 W for 30 s (M1), 350 W for 60 s (M2), and 150 W for 300 s (M3). Structural and morphological analyses by XRD and TEM confirmed crystalline CuO with nanoscale dimensions, while FTIR and Raman spectra indicated the incorporation of phytochemicals that mediated reduction and surface functionalization. UV‐Vis spectroscopy revealed band‐gap modulation and efficient solar‐light absorption, suggesting improved photochemical activity. Photocatalytic tests under solar‐simulated irradiation demonstrated significant degradation of methylene blue, with performance strongly correlated to synthesis conditions and phytochemical‐assisted tailoring of optical properties. Among the evaluated conditions, M2 exhibited the highest apparent rate constant, demonstrating that the microwave power–time program influences the structure performance relationship of CuO synthesized in the presence of M. dubia extracts.