Synergistic experimental and DFT insights for enhanced optoelectronic and photocatalytic performance of CuO_1−xCl_x NPs

We investigate the electronic, optical, structural, and photocatalytic properties of CuO_1−xCl_x nanoparticles by experimental characterization and density functional theory, synthesized via chemical co-precipitation. X-ray diffraction structural analysis suggests the conservation of the monoclinic tenorite phase of CuO with no secondary phases, while Cl doping induced peak shifts in XRD patterns, indicating lattice strain and contraction. FE-SEM and HRTEM morphological studies revealed spherical nanoparticles with increasing particle size upon Cl incorporation. XPS analysis confirms the presence of Cl with the binding energy of 200 eV and reveals the reduction of oxygen vacancy (O_V) after doping, further proving the introduction of Cl in the O sites. Optical measurements by UV–visible spectroscopy showed enhanced visible light absorption and reduced band gaps with Cl doping, corroborated by density functional theory calculations with U ∼ 6 eV for Cu. We further explore the successful incorporation of Cl into CuO in the context of the EDS experimental analysis. Lattice vacancies form due to chlorine integration, while the released electrons are predominantly occupied as defect states in the forbidden zone. These defect states modified the electronic band structure, unveiling the decrease in the band gap. Rhodamine B photocatalytic degradation under UV light demonstrated improved efficiency with increasing Cl concentration, attributed to better charge separation and reduced recombination rates. The active species controlling photocatalytic reactions were identified by scavenger test. These findings highlight the potential of Cl-doped CuO for the photocatalytic degradation of complex organic dyes.