Dye wastewater treatment using nonthermal plasma-treated copper oxide nanoparticles produced through electrolysis technique

Abstract Copper oxide nanoparticles (CuO-NPs) were produced by implementing an electrolysis technique. The prepared CuO-NPs were processed with nonthermal microwave plasma to check the effect of plasma treatment on their morphology and photocatalytic response. The plasma processed and blank CuO-NPs samples were used in dye degradation and water splitting applications under simulated sunlight. The blank sample posed undefined morphology, which turned to spherical particles on plasma processing. The particle size grows slightly with processing time. The blank samples showed a crystallite size of 4.512 nm, which grew to 5.34 nm, 5.40 nm, and 5.49 nm after plasma processing for 10, 20, and 30 min, respectively. The lattice parameter UT sample was measured to be 2.4308 Å, with turned to 3.1091, 3.2112, and 3.3099 after 10, 20, and 30 min of plasma treatment, respectively. Similarly, band gap of CuO-NPs reduced from 2.4 eV to 2.24 eV after plasma processing for 30 min. The porosity of the nanoparticles also showed a similar trend. The plasma processing of CuO-NPs for 30 min produced the best results for photocatalytic water splitting and dye degradation applications. The photocatalytic activity revealed hydrogen evolution of 38.05 mmol.g⁻¹.h⁻¹ and dye removal efficiency of 91%.