Synthesis of superparamagnetic biocidal superior solar photocatalytic Fe3O4-implanted Ag2S-capped ZnO micro-clubbells

Abstract

Semiconductor-photocatalytic mineralization of organics is an emerging technology. However, recovery of the photocatalytic particles post pollutant-mineralization is a stumbling block for adoption of this technique. Implantation of magnetic core in the particulate photocatalyst ensures magnetic recovery. The magnetic core, deeply buried in the photocatalytic semiconductor lattice, is secluded from the photocatalyst/effluent interface and has insignificant influence on the photocatalytic processes. As the magnetic core is concealed its photocorrosion is overcome. With this, we report synthesis of Fe 3 O 4-implanted Ag 2 S-capped ZnO microstructure by a two-step hydrothermal process. Scanning electron micrograph shows the synthesized particles as micro-clubbell-shaped. The energy dispersive X-ray spectrum confirms the presence of the constituent elements and the elemental mapping images display the even distribution of the constituent elements in the micro-clubbells. The X-ray diffractogram and the Raman spectrum show ZnO in zincite structure and Ag 2 S in acanthite phase. The synthesized microstructure and precursor Fe 3 O 4 nanocrystals are superparamagnetic and their magnetic properties are comparable. The charge-transfer resistance of the microstructure is more than 20-fold that of Fe 3 O 4 nanocrystals (New J Chem 40:1845-1852, 2016). The micro-clubbells absorb in the entire visible region and displays strong absorption in the UV-A region. The microcomposite exhibits green and strong blue-green emissions and the lifetime of photogenerated charge carriers is 10 ps. The synthesized microsized clubbell is mesoporous and its specific surface area is comparable to those of nanostructured composites. The synthesized microcomposite (1) displays superior photocatalytic activity under natural sunlight and (2) is reusable and magnetically recoverable. In addition, the title microstructure exhibits bactericidal activity, even without direct illumination.

Ni0.5Zn0.5Fe2O4‐dispersed In2O3‐spotted ZnO nanoparticles: Ammonia‐source and surface and photocatalytic properties

“…The intensity of emission reflects the population of defects generated. The violet, blue, and blue‐green emissions stem from bound excitons and band‐edge free excitons 32,33,41,42 . The violet light‐emission shown by Ni 0.5 Zn 0.5 Fe 2 O 4 /ZnO‐In 2 O 3 (T) nanoparticles is sharp whereas those by Ni 0.5 Zn 0.5 Fe 2 O 4 /ZnO‐In 2 O 3 (A) and pristine ZnO nanocrystals are broad.…”

“…The violet, blue, and bluegreen emissions stem from bound excitons and band-edge free excitons. 32,33,41,42 The violet light-emission shown by Oxygen vacancies and other vacancy-related defects are responsible for green emission 32,33,41 ; the energy associated with the transfer of electron to VB from deep-level donor of ionized oxygen vacancies matches with the green emission. 35,37,38,41 Excess oxygen in ZnO lattice gives rise to yellow emission, and lack of such emission indicates the absence of excess oxygen in both the synthesized nanoparticles and also in pristine ZnO nanocrystals.…”