Cu2O-CuO@biochar composite: Synthesis, characterization and its efficient photocatalytic performance

This research focuses on the facile hydrothermal preparation of Cu₂O-CuO@biochar (Cu₂O-CuO@BC) composites of different BC content (0.5, 1.0, and 2.0 g/L) as efficient photocatalysts for the decomposition and mineralization of Reactive Orange 29 (RO29). The textural and morphological properties of biochar-based composites were studied utilizing BET, TEM, and SEM analyses. Moreover, EDX, XRD, UV-Vis, DRS and FTIR characterization was carried out to evaluate the elemental composition, crystalline structure, optical characteristics and functional groups of the samples, respectively. The Cu₂O-CuO@BC-1.0 composite with a BC content of 1.0 g/L exhibited superior photocatalytic performance than the individual counterparts BC and Cu₂O-CuO, due to its narrow band gap and high surface area. These characteristics led to the synergetic ability of UV irradiation and photocatalytic performance of Cu₂O-CuO@BC to generate oxidizing species and subsequent radical reactions. The generation of some by-products was verified using GC-MS analysis and accordingly, a possible pathway was proposed. 94.12% degradation efficiency of RO29 was obtained by Cu₂O-CuO@BC-1.0 composite at the natural pH of RO29 solution (8.9) and initial RO29 concentration of 20 mg/L after 90 min of photocatalysis. Under identical conditions, 47.31% and 79.62% COD removal efficiencies were observed after 90 and 180 min treatment, respectively.