Co doped ZrO2 nanoparticles: An efficient visible light triggered photocatalyst with enhanced structural, optical and dielectric characteristics

In this work ZrO2 and Co doped ZrO2 (tetragonal) nanoparticles (NPs) were prepared via facile co-precipitation method. Multivalent Co-ZrO2 NPs were investigated for structural, optical, magnetic, dielectric and photocatalytic applications. A detailed structural analysis confirmed successful substitution of dopant ions in zirconia lattice with an average crystallite size of 18.0 +/- 1.7 nm. SEM analysis depicted narrow, spherical like morphology for both pure ZrO2 and Co-ZrO2 NPs. DRS spectra revealed substantial tuning of band gap from 3.7 to 2.12 eV with Co doping owing to crystal defects. Moreover, incorporation of Co contents in ZrO2 matrix had significantly enhanced the dielectric constant up to 2.8 x 10(4) with a very low loss, which is attributed to the size of the nanoparticles along with presence of localized states between valence band and conduction band. The room temperature ferromagnetism (RTF), driven by creation of oxygen vacancies coupled with dopant concentration in the host lattice, enhanced the degradation process. Interestingly, Co-ZrO2 NPs have shown effective visible light triggered photocatalytic activity against methylene blue (MB). The significant removal of MB (96.5%) was achieved using 10% Co doped ZrO2 NPs, which was consigned to the efficient control on the recombination rate. These findings illustrate that Co-ZrO2 NPs can be a profound alternate for futuristic high frequency devices, and waste water treatment processes.