Hybrid metal oxides quantum dots/TiO2 block composites: Facile synthesis and photocatalysis application

Adsorption behavior of silver quantum dots by a novel super magnetic CoFe2O4-biochar-polymeric nanocomposite

Recent industrial development and research progress in nanotechnology have led to the release of a number of nanomaterials with particle sizes (1-10 nm) which are categorized as quantum dots (QDs) in aquatic system. Disposal away of such QDs will cause potential pollution to the environment. Therefore, removal of disposed QDs from wastewater represents a challenging research subject for scientists and engineers. Hence, the objective of this study is devoted to assess the process of coagulative removal of silver quantum dots (Ag-QDs), as an example, from water by a novel super magnetic nanocomposite. Such material was aimed to prepare from the chemical combination and reaction of a generated Citrus sinensis and Citrus reticulata peels biochar (SMCsr-B) with spinel cobalt ferrite (CoFe₂O₄) as a super-magnetic source. The produced (SMCsr-B) was then crosslinked with polyurea-formaldehyde polymer (PUF) using EDA in only two minutes via microwave irradiation to produce (SMCsr-B/PUF). The SEM, EDX, FT-IR, XRD, and XPS analyses of the assembled (SMCsr-B/PUF) nanocomposite were acquired to confirm surface morphology and chemical structure. Controlling experimental factors were investigated as pH, time, and Ag-QDs pollutant concentration using microwave irradiative removal technique to establish the efficiency of coagulative adsorption of Ag-QDs onto (SMCsr-B/PUF). The solution (pH 5) was proved to exhibit the higher removal percentages of Ag-QDs in 15-25 s. SMCsr-B/PUF nanocomposite exhibited high removal efficiency as 93.12%, 92.39% and 92.48% upon using 20, 40 and 60 mg L^-1 of Ag-QDs, respectively in presence of 10 mM NaCl. The kinetic and equilibrium adsorption data were best fitted to Freundlich model. The prepared SMCsr-B/PUF was successfully utilized as an efficient super magnetic nanocomposite for removal and recovery of Ag-QDs from aqueous environment.

Quantum dot-decorated semiconductor micro- and nanoparticles: A review of their synthesis, characterization and application in photocatalysis

Quantum dot (QD)-decorated semiconductor micro- and nanoparticles are a new class of functional nanomaterials that have attracted considerable interest for their unique structural, optical and electronic properties that result from the large surface-to-volume ratio and the quantum confinement effect. In addition, because of QDs' excellent light-harvesting capacity, unique photoinduced electron transfer, and up-conversion behaviour, semiconductor nanoparticles decorated with quantum dots have been used widely in photocatalytic applications for the degradation of organic pollutants in both the gas and aqueous phases. This review is a comprehensive overview of the recent progress in synthesis methods for quantum dots and quantum dot-decorated semiconductor composites with an emphasis on their composition, morphology and optical behaviour. Furthermore, various approaches used for the preparation of QD-based composites are discussed in detail with respect to visible and UV light-induced photoactivity. Finally, an outlook on future development is proposed with the goal of overcoming challenges and stimulating further research into this promising field.

Visible light photocatalytic mineralization of 17α-ethinyl estradiol (EE2) and hydrogen evolution over silver and strontium modified TiO2 nanoparticles: mechanisms and phytotoxicity assessment

This study focusses on the novel synthesis of silver and strontium modified TiO₂ nanocomposite through a sol–gel method, which was then utilized for visible light degradation of EE2 and hydrogen production for the first time.