Photoreduction coupling of NiO/SiO2 nanocomposite with palladium and yttria nanoparticles: Visible-light-driven photocatalysts

Abstract A photoreduction coupling of sol-gel derived NiO/SiO2 nanocomposites with palladium (Pd) and yttria (Y) nanoparticles was developed to produce efficient visible-light-driven photocatalysts. The XRD and Raman spectra revealed a highly crystalline, cubic NiO phase with an amorphous structure of SiO2. Upon coupling with either Pd or Y nanoparticles, the material crystallinity was preserved with a narrowing in bandgap energy. The N2 sorption analysis confirmed the mesoporous nature of the synthesized materials, with higher BET surface area for the doped NiO/SiO2. The SEM and TEM images revealed spherical nanoparticles formation with typical lattice fringes and the presence of Pd and Y nanoparticles was confirmed by EDS analysis. Compared to the undoped NiO/SiO2 photocatalyst, the developed Pd and Y doped photocatalysts exhibited a remarkable enhancement in the photocatalytic degradation of methylene blue (MB) dye at ambient conditions. The reaction rate constant (k) of Pd and Y doped NiO/SiO2 photocatalysts was enhanced and found to be respectively 2.18 × 10−4 and 2.02 × 10−4 min-1 compared to 1.32 × 10−4 min-1 obtained for undoped NiO/SiO2 photocatalyst. The enhancement in the photodegradation efficiency of doped samples was attributed to the high crystallinity, textural characteristics with a high specific surface area and increased light absorption capability with efficient separation of charge carriers. The current developed Pd and Y doped NiO/SiO2 photocatalysts exhibited outstanding stability during the recyclability.