Optical, dye degradation, and electrochemical sensor studies of CeO2 and CuO nanoparticles by pomegranate peel

Abstract

This study presents a comparative investigation of cerium oxide (CeO₂) and copper oxide (CuO) nanoparticles synthesized via the solution combustion method (SCM) using pomegranate peel as a green fuel. The synthesized materials were systematically characterized for their structural, morphological, optical, and electrochemical properties using XRD, SEM, UV–Vis spectroscopy, FTIR, and CV techniques. Optical studies were analyzed to understand their functional behaviour, including transmittance, refractive index, dielectric constant, optical conductivity, and absorption coefficient.

The photocatalytic potential of CeO₂ and CuO was evaluated for the degradation of malachite green under UV light, achieving degradation efficiencies of 97.4 % and 91.56 %, respectively, following first-order kinetics. Additional photocatalytic performance parameters such as half-life (T₁/₂), total organic carbon (TOC) removal, pH dependence, scavenger effects, and recyclability were systematically studied. Electrochemical investigations were conducted using a nickel mesh electrode, revealing redox behaviour in 1 M NaOH through cyclic voltammetry (CV) with specific capacitances of 95 F/g (CeO₂) and 64 F/g (CuO). Diffusion coefficients were determined as 4.365 × 10⁻⁵ cm²/s for CeO₂ and 3.137 × 10⁻⁵ cm²/s for CuO. Furthermore, via CV analysis, CeO₂ and CuO were explored as electrochemical sensors for heavy metal detection, demonstrating sensitivity towards mercury (Hg) and cadmium (Cd) in the 1–5 mM range.

This work highlights the dual functionality of CeO₂ and CuO nanoparticles as effective photocatalysts and electrochemical sensors, offering promising applications in environmental remediation and heavy metal detection.