Agro-waste ash extracts facilitated green synthesis of CuO nanoparticles with efficient catalytic and photocatalytic activities for environmental remediation

Abstract

The utilization of natural resources as a green, sustainable, and cost-effective platform for nanomaterial fabrication has garnered significant attention from researchers. This study focuses on the green and sustainable synthesis of copper oxide nanoparticles (CuONPs) using agro-wastes—specifically papaya bark (PB) and banana stem (BS) ash extracts. These extracts not only serve as natural bases but also enable sustainable nanoparticle fabrication via a straightforward method under ambient stirring conditions, eliminating the need for microwave or hydrothermal treatments. The synthesized CuONPs were extensively characterized using UV, FT-IR, XPS, XRD, SEM, and TEM analyses, revealing average particle sizes of 16.67 and 12.56 nm with spherical and rod-shaped morphologies, respectively. The elemental composition of the agro-wastes was analysed via EDX analysis. UV–visible spectroscopy showed band gaps of 2.72 and 3.30 eV. The photocatalytic performance of the CuONPs was evaluated using Rhodamine B and Eosin yellow dyes under sunlight, with the degradation mechanism were also described. Furthermore, the CuONPs demonstrated catalytic activity by facilitating the reduction of 4-nitrophenol to 4-aminophenol in the presence of NaBH₄. This work highlights a sustainable approach for CuO nanostructure synthesis with promising applications in environmental remediation.