LAUSR

A series of ZnO/carbon‐based nanocomposites was successfully synthesized in situ within a starch matrix using a combination of precipitation and microwave‐assisted techniques, aiming at the efficient degradation of methyl orange (MO) under both UV and natural sunlight irradiation. Starch served simultaneously as a carbon source and a polymeric stabilizing agent during the synthesis. The morphology and elemental composition of the resulting nanomaterials were systematically characterized using scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy (EDX), X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), and Fourier‐transform infrared (FTIR) spectroscopy. The Brunauer–Emmett–Teller (BET) method was applied to calculate the specific surface areas. The optical characteristics of the composites were investigated via UV–visible (UV–vis) spectrophotometry and photoluminescence (PL) spectroscopy. The findings revealed that the ZnO/carbon nanocomposite calcined at 400°C exhibited superior photocatalytic performance, achieving a 92% degradation efficiency of MO under UV light in 90 min, and 99% degradation under sunlight within 70 min. These efficiencies were approximately 2.7 and 4.2 times higher, respectively, than those obtained with ZnO/carbon treated at 200°C and pristine ZnO. The underlying photocatalytic mechanism was elucidated through radical scavenging experiments, indicating that hydroxyl radicals (·OH) were the predominant reactive species involved in the degradation process. Additionally, the photocatalytic performance of the ZnO/carbon nanocomposites calcined at 400°C was found to be strongly influenced by both the starch‐to‐precursor ratio and the pH of the synthesis medium.