Engineered oxygen vacancies in NiCo2O4/BiOI heterostructures for enhanced photocatalytic pollutant degradation

Abstract

To address the bottleneck issue of poor carrier separation and transfer efficiency in NiCo₂O₄ photocatalyst, a novel 1D/2D-rod-on-rose-like NiCO₂O₄/BiOI nanohybrid with abundant OV's was successfully synthesized using a single-step hydrothermal method and employed to the photocatalytic degradation of Rhodamine B (RhB). The study revealed that the optimized NiCo₂O₄-OV/BiOI hybrid could possess superior photocatalytic degradation efficiency towards RhB degradation under visible light with a rate constant that was 3.8 and 3.03 times greater than that of BiOI and NiCo₂O₄-OV. Experimental findings indicated that the formation of NiCo₂CO₄-OV/BiOI heterojunction significantly improved the charge separation efficiency and facilitated the formation of surface OV's. These OVs enhanced photogenerated e^--h⁺ separation and increased catalytic efficiency. Quenching experiments results confirmed that both holes and superoxide radicals are playing crucial roles in the degradation process. Thus, an oxygen vacancy and engineering NiCo₂CO₄-OV/BiOI heterojunction-enhanced degradation mechanism was proposed, offering insights for the integration of advanced oxidation technologies and the development of catalytic materials to enhance pollutant degradation efficiency.

Keywords: NiCo2O4/BiOI; Oxygen vacancy; Photocatalysts; Rhodamine B; Visible light.