New Insights into Cu/Cu₂O/CuO Nanocomposite Heterojunction Facilitating Photocatalytic Generation of Green Fuel and Detoxification of Organic Pollutants

Cu/Cu2O/CuO nanocomposites were synthesized using the simple wet chemical approach for the production of dihydrogen as a potential fuel source and for the detoxification of dyes. The formation of Cu/Cu2O/CuO nanocomposites is confirmed by powder X-ray diffraction, whereas the W-H plot revealed the average particle size of nanocomposite approximately 17 nm, which is in good agreement with the Scherrer method and transmission electron microscopy analysis. The uniform distribution of Cu and O elements was supported by the elemental mapping of the nanocomposite. Band gaps of CuO and Cu2O were found to be 1.71 and 1.92 eV, respectively, using diffuse reflectance spectroscopy spectra and Kubelka–Munk functions. The oxygen vacancies in the nanocomposite are confirmed by various analytical spectroscopic techniques, such as electron paramagnetic resonance, Raman, photoluminescence, and X-ray photoelectron spectroscopy (XPS) spectra. The significant boost in the performance of the fabricated nanocomposite was observed and is attributed to the formation of a heterojunction and existence of oxygen vacancy. The nanocomposite demonstrated proficiency in the photocatalytic splitting of water for the production of hydrogen. The maximum hydrogen generation yield (68 μmol g–1) was observed for Cu/Cu2O/CuO nanocomposites along with NiO (co-catalyst) and methanol as a hole scavenger as well as an electron donor. Moreover, the degradation of congo red (CR) and malachite green (MG) dyes was also investigated and the efficiency of the nanocomposite was found to be 80 and 60%, respectively, after 120 min of light irradiation. The stability of nanocomposites after photocatalysis was investigated by the XPS spectrum of the nanocomposite. Explicitly, the area and broadening of the O 1s XPS spectrum demonstrated higher degradation of CR dye as compared to MG dye.