Oxygen vacancy engineering and synergistic effects of Ce-doping in NiO octahedra for enhanced photodegradation of organic and antibiotic pollutants

This study systematically investigates the effect of cerium (Ce) doping on the photocatalytic performance of nickel oxide (NiO) under visible light irradiation. The introduction of Ce 3+ /Ce 4+ ions into the NiO lattice induces lattice strain and oxygen vacancies, enhancing charge separation and visible-light absorption. These defects promote the generation of reactive oxygen species (O 2 • - and •OH), which drive the degradation of organic pollutants. Structural, optical, and electronic analyses of NiO doped with 1%, 3%, and 5% Ce highlight the key role of the Ce 3+ /Ce 4+ redox couple in facilitating thermally assisted polaronic hopping and improving charge transport. Notably, Ce-NiO-3% showed higher surface area of 114.4 m 2 g -1 than pure NiO. Among all samples, Ce–NiO-3% showed the best photocatalytic activity, degrading over 95% of methylene blue within 90 minutes. The enhanced activity arises from the synergistic effects of bandgap narrowing, defect engineering, and redox-mediated ROS generation. This work provides valuable insights for designing efficient, defect-engineered Ce–NiO photocatalysts for environmental remediation. 1 Facile synthesis of Ce:NiO NPs via one pot solution-phase thermal method is reported 2 Remarkable reduction in crystallite size from 22 to 13 nm and reduction in Band gap of NiO from 3.27 to 2.98 eV was noticed with Ce-doping. 3 3% Ce:NiO exhibited 95% degradation efficiency of MB within 90 min. under visible light 4 Improved performance is attributed to synergistic effects of bandgap narrowing, defect engineering, and redox-mediated ROS generation 5 Also, the stability, elemental trapping and degradation mechanism is reported