Photoelectrochemical performance of hydrogenated ZnO/CdS core–shell nanorod arrays

Fast photodegradation of antibiotics and dyes by anionic surfactant-aided CdS/ZnO nanodispersion

Photocatalytic technology has broad applications in energy and environmental science. In this study, we synthesized a type II heterojunction CdS/ZnO nanodispersion by means of one-pot precipitation. Different from previous studies,...

Novel Low Temperature Route to Produce CdS/ZnO Composite Nanofibers as Effective Photocatalysts

In this work, CdS/ZnO composite nanofibers (NFs) were prepared by the electrospinning of a sol–gel comprised of poly(caprolactone), zinc acetate dihydrate, cadmium acetate dihydrate, and ammonium sulfide. The electrospun NF mats were calcined under vacuum in an argon (Ar) atmosphere at 200 °C for 1 h. Standard physiochemical analysis techniques demonstrated the formation of the crystalline hexagonal phase of CdS and ZnO. Composite NFs showed good photocatalytic degradation of methylene blue (MB) dye under visible light irradiation compared to their counterparts. CdS nanoparticles, ZnO nanofibers, and composite NFs photodegraded 35.5%, 47.3%, and 90% of the MB dye, respectively, within 100 min. The reaction kinetics of MB photodegradation using the composite NFs followed the pseudo-first-order relation. Owing to their facile preparation and good photodegradation ability, the proposed method can be used to prepare various photocatalysts for wastewater treatment.

Theoretical investigation on the optical and EPR spectra for Cu2+ -doped ZnO-CdS nanocomposites

The three optical absorption bands and EPR parameters of the [CuO6 ]10- center in the ZnO-CdS composite nanopowders are theoretically studied from the perturbation formulas based on the cluster approach. In the formulas, the contributions to EPR parameters arising from the ligand orbital and spin-orbit coupling interactions via covalence effect are considered. For the studied [CuO6 ]10- cluster, the Cu-O bond lengths are suggested to show a relative elongation ratio ρ (≈ 4.1%) along the z-axis due to Jahn-Teller effect. The defect models suggested in this work are different from the previous assumption that the impurity Cu2+ can replace the host Zn2+ site when it enters the lattices of the ΖnO and ΖnS nanocrystals, forming the tetrahedral [CuΧ4 ]6- clusters (Χ = O, S). The validity of the proposed model is discussed. The differences between the present calculations and the previous ones for the interstitial Cu2+ center in ZnO nanocrystals are analyzed in view of the dissimilar impurity behaviors due to the new composition CdS and distinct preparation conditions.

Synthesis and Progress of New Oxygen-Vacant Electrode Materials for High-Energy Rechargeable Battery Applications

During the last few years, a great amount of oxygen-vacant materials have been synthetized and applied as electrodes for electrochemical storage. The presence of oxygen vacancies leads to an increase in the conductivity and the diffusion coefficient; consequently, the controllable synthesis of oxygen vacancy plays an important role in improving the electrochemical performance, including achieving high specific capacitance, high power density, high energy density, and good cycling stability of the electrode materials for batteries. This review mainly focuses on research progress in the preparation of oxygen-vacant nanostructures and the application of materials with oxygen vacancies in various batteries (such as lithium-ion, lithium-oxygen, and sodium-ion batteries). Challenges related to and opportunities for oxygen-vacant materials are also provided.

Visible-light-driven photocatalytic degradation of safranin-T dye using functionalized graphene oxide nanosheet (FGS)/ZnO nanocomposites

FGS/ZnO NCs with excellent photocatalytic activity towards photodegradation of safranin-T have been synthesized via a facile and economical solution route.

CdS–MoS2 heterostructures on Mo substrates via in situ sulfurization for efficient photoelectrochemical hydrogen generation

CdS–MoS₂ photoelectrode with a double layers core shell structure was prepared on Mo substrate through using a simple electrodeposition and– in situ sulfurization method on Mo substrate.

Two-dimensional CdS intercalated ZnO nanorods: a concise study on interfacial band structure modification

The intercalation of CdS on ZnO nanorods modified the optical band gap effectively and improved the solar cell performance significantly.

Controllable synthesis of CdS/WO3 heterostructures with enhanced photoelectrochemical performance

With the increasing energy and environmental problems, photoelectrochemical (PEC) water splitting has recently attracted a great deal of attention.

Spectral investigations on undoped and Cu²⁺ doped ZnO-CdS composite nanopowders

Undoped and Cu(2+) doped ZnO-CdS composite nanopowders were synthesized by simple chemical precipitation method. Structural and spectroscopic properties of the prepared samples have been characterized by XRD, SEM with EDS, TEM, FT-IR, UV-Vis, EPR and Photoluminescence studies. X-ray diffraction pattern contains a series of peaks corresponds to hexagonal phase of ZnO and CdS. The average crystallite sizes of undoped and Cu(2+) doped samples are determined and are in the range of 25-30 nm. SEM and TEM micrographs reveal that the samples show spherical like structures with little agglomeration. FT-IR spectra show the fundamental mode of vibrations of ZnO at 515 cm(-1), CdS at 621 cm(-1) and other functional groups. Optical absorption spectrum of Cu(2+) doped sample consists of three bands at 665, 823 and 1192 nm attributed to the transitions (2)B1g→(2)Eg, (2)B2g and (2)A1g respectively. Crystal field and tetragonal field parameters are evaluated as Dq=1214, Ds=1610 and Dt=389 cm(-1). From EPR, spin-Hamiltonian and hyperfine splitting parameters are evaluated for Cu(2+) doped sample as g‖=2.3391, g⊥=2.0550 and A‖=130×10(-4) cm(-1), A⊥=36×10(-4) cm(-1). The optical and EPR data suggests that Cu(2+) entered into host lattice as tetragonally distorted octahedral site symmetry. PL spectra consists two emission bands at 367, 380 nm in UV region. A sharp blue emission peak at 425 nm and a broad green emission peak in the range of 450-570 nm are observed. The enhanced visible emission is observed after doping.

Photosensing performance of branched CdS/ZnO heterostructures as revealed by in situ TEM and photodetector tests

CdS/ZnO branched heterostructures have been successfully synthesized by combining thermal vapour deposition and a hydrothermal method. Drastic optoelectronic performance enhancement of such heterostructures was revealed, compared to plain CdS nanobelts, as documented by comparative in situ optoelectronic studies on corresponding individual nanostructures using an originally designed laser-compatible transmission electron microscopy (TEM) technique. Furthermore, flexible thin-film based photodetectors based on standard CdS nanobelts and newly prepared CdS/ZnO heterostructures were fabricated on PET substrates, and comparative photocurrent and photo-responsivity measurements thoroughly verified the in situ TEM results. The CdS/ZnO branched heterostructures were found to have better performance than standard CdS nanobelts for optoelectronic applications with respect to the photocurrent to dark current ratio and responsivity.

Facile electrochemical synthesis of CeO2 hierarchical nanorods and nanowires with excellent photocatalytic activities

A simple, cost-effective and controllable electrochemical method has been developed to synthesize free-standing CeO₂ hierarchical nanorods and nanowires.