Synthesis of Cu‐Cu₂O nanoparticles using coffee husk as reducing agent and stabilizer: Impact of reaction pH medium on particle size

Cu‐Cu 2 O nanoparticles (NPs) were synthesized using coffee husk (CH) as a reducing agent and stabilizer via CuSO 4 precursor. The size of Cu‐Cu 2 O NPs, determined by scanning electron microscopy, decreased with increasing reaction pH medium. Particularly, the average sizes were 51.5, 47.3, and 43.2 nm at pH 8, 9, and 10, respectively. The structural characteristics of Cu‐Cu 2 O NPs/CH were analyzed using X‐ray diffraction and Fourier‐transform infrared spectroscopy. The elemental composition in the nanocomposite was identified using energy‐dispersive X‐ray spectroscopy, while the valence state of Cu was analyzed via absorption spectroscopy and iodometric titration. Moreover, the degradation efficiency of the plant toxin caffeine by Cu‐Cu 2 O NPs increased correspondingly with the reaction pH medium. Particularly, the caffeine degradation efficiency increased from 94.80% to 97.03% as the pH value increased from 8 to 10. Thus, the synthesized Cu‐Cu 2 O NPs/CH composite has potential utilization as micronutrient organic fertilizer and soil improver, contributing to sustainable agriculture.