Abstract A green chemistry approach utilizing coffee husk (CH) biomass waste as both a reducing agent and a carrier for the synthesis of Cu-based nanoparticles (NPs) was implemented. The reducing agents in CH, including reducing sugar and total polyphenol have been quantified. The average size of Cu based NPs deposited to CH-was determined by scanning electron microscopy from 40.4 nm to 62.6 nm and showed a dependence on the CuSO4 precursor content from 2% to 5%, respectively. The prepared Cu-based/CH nanocomposites were characterized by X-ray diffraction, Fourier transform infrared, and energy dispersive X-ray. The reduction efficiency of Cu2+ to Cu0 and Cu2O by reducing agent in CH reached 97.27–98.56% after 30 min of reaction at 105°C. The synthesized Cu-based NPs demonstrated the ability to degrade the plant toxin caffeine in CH with an efficiency of 95.46–96.09%. The Cu-based/CH nanocomposite containing ~3% Cu showed in vitro nematicidal activity against rootknot Meloidogyne incognita with mortality reaching 85.46–100% at 20–35 mg/L Cu. In the nematode infection experiment on coffee pots, the Cu-based/CH nanocomposite achieved 100% nematode control at 35 mg/L Cu. These findings indicated that the Cu-based/CH nanocomposite has the potential to be used as an organic-micronutrient fertilizer and a nematicide for plants in agriculture.
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