A ZnO@graphene composite exhibits enhanced performance for photocatalytic degradation and filtered removal of RhB dye, in comparison with ZnO and graphene, highlighting its potential applications for a variety of environmental issues.

In this paper, a Fe₃O₄ nanocrystals@graphene composite (FGC) was synthesized via a chemical deposition method by using graphene oxide as a precursor. We also investigate the structures, physicochemical properties and applications of FGCs, involving superparamagnetic performance, and use as supercapacitors and lithium ion battery (LIBs). The results showed that the Fe₃O₄ NCs were formed and incorporated onto the surface of the graphene sheets. The composite material FGC with a micrometre scale structure possessed similar size as the graphene sheets and exhibited superparamagnetic behavior at room temperature. The supercapacitance values of the FGC composites were enlarged compared with those of the graphene sheets or Fe₃O₄ NCs, which is attributed to the interaction between the Fe₃O₄ NCs and the graphene sheets. Meanwhile, a superior rechargeable stability of FGCs used as an anode material in LIBs can be observed.

Composite Bi@Bi₂O₃ microspheres have been synthesized via a microwave-assisted solvothermal route. The Bi@Bi₂O₃ microspheres had a narrow size distribution in the range 1.2–2.8 mm. Glucose was selected as the reductant, BiCl₃ as the bismuth source, and ethylene glycol (EG) as the solvent in the synthesis system. The as-synthesized sample was characterized by X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), particle diameter distribution, energy dispersive X-ray spectroscopy (EDS), ultraviolet-visible (UV-vis) spectroscopy, and photoluminescence (PL) spectroscopy. The photocatalytic activities of the Bi@Bi₂O₃ microspheres were evaluated by the photodegradation of rhodamine B (RhB) and methyl orange (MO) dyes under UV light irradiation. The degradation reached ∼96.6% for RhB and 100% for MO after 4 h reaction in the presence of the as-synthesized Bi@Bi₂O₃ microspheres.

Cu₂O@reduced graphene oxide composite displays a good ability to remove dyes from water and high stability in supercapacitors, highlighting potential applications in environmental and energy storage issues.