Cerium oxide nanoparticles (CeO₂NPs) were fabricated and grown on graphene sheets using a facile, low cost hydrothermal approach and subsequently characterized using different standard characterization techniques. X-ray photoelectron spectroscopy and electron paramagnetic resonance revealed the changes in surface states, composition, changes in Ce⁴⁺to Ce³⁺ratio, and other defects. Transmission electron microscopy (TEM) and high resolution TEM revealed that the fabricated CeO₂NPs to be spherical with particle size of ~10–12 nm. Combination of defects in CeO₂NPs with optimal amount of two-dimensional graphene sheets had a significant effect on the properties of the resulting hybrid CeO₂-Graphene nanostructures, such as improved optical, photocatalytic, and photocapacitive performance. The excellent photocatalytic degradation performances were examined by monitoring their ability to degrade Congo red ~94.5% and methylene blue dye ~98% under visible light irradiation. The photoelectrode performance had a maximum photocapacitance of 177.54 Fg⁻¹and exhibited regular capacitive behavior. Therefore, the Ce³⁺-ion, surface-oxygen-vacancies, and defects-induced behavior can be attributed to the suppression of the recombination of photo-generated electron–hole pairs due to the rapid charge transfer between the CeO₂NPs and graphene sheets. These findings will have a profound effect on the use of CeO₂-Graphene nanostructures for future energy and environment-related applications.

This paper reports an environmentally benign, simple, cost efficient, one-step, surfactant free, and biogenic synthesis of a silver–graphene (Ag–graphene) nanocomposite using an electrochemically active biofilm (EAB). The EAB was used for the reduction of Ag⁺ to Ag⁰ onto the graphene sheets. The morphology, structure, composition, and optical properties and contact angle of the Ag–graphene were obtained using a range of techniques which confirmed the anchoring/presence of silver nanoparticles (AgNPs) onto the graphene sheets. The photocatalytic activity of Ag–graphene was evaluated by the degradation of methylene blue and Congo red dye in aqueous solution at an ambient temperature in the dark and under visible-light irradiation. The results showed that the photocatalytic activity of the Ag–graphene nanocomposite was enhanced significantly by the loading of AgNPs in the graphene sheets. Contact angle measurements confirm the hydrophilic nature of the Ag–graphene nanocomposite which is very helpful in photocatalysis. The electrical conductivity and photocurrent measurements of the Ag–graphene nanocomposite exhibited a much better performance than P–graphene. This study highlights the design of a novel facile synthetic route for a new photocatalyst using the SPR of Ag and graphene as a support. The as-synthesized Ag–graphene nanocomposite has potential applications in photocatalytic degradation, photoelectrodes and optoelectronic devices.

Visible light-induced photocatalytic degradation of organic pollutants using WO₃ nanorods–graphene nanocomposite.