Tuning crystal phase and morphology of copper selenide nanostructures and their visible-light photocatalytic applications to degrade organic pollutants

ZnO/CuSe composite-mediated bandgap modulation for enhanced photocatalytic performance against methyl blue dye

The removal of toxic dye pigments from the environment is of utmost importance since even trace amounts of these pollutants can lead to harmful impacts on ecosystems. Heterogeneous photocatalysis is a potential technique for eliminating microbiological, inorganic, and organic pollutants from wastewater. Here, we report the band gap alteration of ZnO by making its composites with CuSe to enhance photocatalytic activity. The purpose is to develop metal oxide nanocomposites (ZnO/CuSe) as an effective and efficient material for the photodegradation of methyl blue. The photocatalysts, ZnO nanorods, CuSe, and ZnO/CuSe nanocomposites of different weight ratios were synthesized by the simple and cost-effective technique of precipitation. UV-Vis spectra verified that the ZnO/CuSe photocatalyst improved absorption in the visible region. The optical bandgap of ZnO/CuSe nanocomposites reduced from 3.37 to 2.68 eV when CuSe concentration increased from 10 to 50%. ZnO/CuSe composites demonstrated better photocatalytic activity than ZnO when exposed to UV-visible light. The pure ZnO nanorods could absorb UV light and the nanocomposites could absorb visible light only; this was attributed to the transfer of excited high-energy electrons from ZnO to CuSe.

Reversible electrochemical conversion from selenium to cuprous selenide

Using elemental selenium as an electrode, the redox-active Cu²⁺/Cu⁺ ion is reversibly hosted via the sequential conversion reactions of Se → CuSe → Cu₃Se₂ → Cu₂Se. The four-electron redox process from Se to Cu₂Se produces a high initial specific capacity of 1233 mA h g^-1 based on the mass of selenium alone or 472 mA h g^-1 based on the mass of Cu₂Se, the fully discharged product.

Transition metal selenides and diselenides: Hydrothermal fabrication, investigation of morphology, particle size and and their applications in photocatalyst

This review investigates hydrothermal synthesis of metal selenides and diselenides. Briefly, structures, applications and formation mechanisms are studied. The strategies for developing metal selenides, including NiSe, NiSe₂, Ni₃Se₂, CdSe, FeSe₂, MnSe₂, CoSe, CuSe, Cu_1.8Se, CuSe₂, Cu₃Se₂ and ZnSe are discussed. More of 50 hydrothermal methods used for the synthesis of metal selenides are discussed. As well as the investigation of the photocatalytic activities of these metal selenides are followed by different synthesis methods and strategies employed for the synthesis of them.

Controllable Conversion of CdNCN Nanoparticles into Various Chalcogenide Nanostructures for Photo-driven Applications

Semiconductor nanocrystals of tunable shell/core configurations have great potential in photo-driven applications such as photoluminescence and photocatalysis, but few strategies realize a controllable synthesis with respect to both the size of the core and the shell with high crystallinity. Here, a new synthetic method based on cadmium cyanamide (CdNCN) nanoparticle anion exchange reactions was developed to access solid or hollow CdSe nanocrystals with tunable size and CdNCN@CdS heterostructures with modulated shell/core thickness. The gradual shift and narrow width of photoluminescence features demonstrate the high crystallinity and monodispersity of the resulting CdSe nanocrystals. In the CdNCN@CdS heterostructures, synergistic effects of the photocarrier separation is observed between the CdS shell and CdNCN core, which leads to great improvement in photocatalysis with optimized shell/core ratio.