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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.

Superparamagnetic Fe 3 O 4 implanted and CdS coupled ZnO (Fe 3 O 4 /ZnO-CdS) microrods were synthesised by a two-step hydrothermal method. Fe 3 O 4 /ZnO-CdS is superparamagnetic and is activated by visible light for solar photocatalysis. It is magnetically recoverable and reusable and exhibits excellent photocatalytic activity under natural sunlight.

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