CdS Microspheres Research Articles

Synthesis of Hierarchical CdS/NiS Photocatalysts Using Ni-MOF-74 as Template for Efficient Ethanol Conversion and Hydrogen Production under Visible Light.

The conversion of ethanol into high-valuable chemicals and H2 by photocatalytic process provides a sustainable approach to produce carbon-chain-prolonged chemicals and hydrogen energy. In this article, Ni-MOF-74 was added to fabricate the hierarchical CdS/NiS-N composites with an elevated specific surface area during the hydrothermal synthesis of CdS microsphere, and the Ni-MOF-74 facilitate the self-assemble growth of CdS and provide a source of Ni for the formation of NiS. The as-prepared photocatalyst was subjected to photocatalytic ethanol conversion, and the hierarchical composite material CdS/NiS-N (100) formed by adding 100 mg of Ni-MOF-74 exhibits the highest photocatalytic activity and stability in an ethanol aqueous solution with a water content of 10 %. Under visible light irradiation, the conversion rate of ethanol reached 15.2 % at the photocatalytic reaction of 5 h. The selectivity of 2,3-butanediol(2,3-BDO) was 25 %, and the selectivity of acetaldehyde(AA) was 63 %. Through various characterizations, it has been proven that a large specific surface area and the coupling interface between CdS and NiS are key factors in improving photocatalytic performance. This work provides an effective strategy for constructing photocatalysts with coupled cocatalysts/semiconductors and large specific surface areas.

Constructing nanoparticle-assembled CdS microspheres on a FeVO4 nanopolyhedrons photoanode for enhanced photoelectrochemical performance

Improving the light energy utilization to augment the charge carrier concentration and modulating the band alignment to facilitate charge carrier transport and separation are essential for semiconductor photoanode to achieve high-efficiently photoelectrochemical (PEC) performance. Herein, a novel FeVO4 nanopolyhedrons photoanode modified by nanoparticle-assembled CdS microspheres is constructed through an in-situ solid-state transformation and a chemical bath deposition, successively, to augment the concentration of carriers by improving light utilization and facilitate efficient transport and separation of carriers by building type-II structure for efficient PEC performance. The constructed nanoparticle-assembled CdS microspheres modified FeVO4 nanopolyhedrons photoanode generates a drastic improvement in photocurrent, which is 29 times higher than that of pristine FeVO4 nanopolyhedrons photoanode at 0.4 V vs. Ag/AgCl under AM 1.5 G simulated solar light irradiation. The experimental measurements of light absorption evidence that the modification of nanoparticle-assembled CdS microspheres substantially improves light harvesting ability of FeVO4 nanopolyhedrons from 300 to 800 nm for substantially generating charge carriers. Spectral measurements of X-ray photoelectron spectroscopy evidence that a band alignment of type-II structure is established at FeVO4/CdS interface, building directional interface charge transport channel for efficient transfer and separation of photoinduced charge carriers. This study offers a referable strategy for designing photoanodes to achieve PEC performance from the perspective of light energy utilization and interface energetics engineering.

Ultrasensitive photoelectrochemical aptasensor for carbendazim detection based on in-situ constructing Schottky junction via photoreducing Pd nanoparticles onto CdS microsphere

Carbendazim (CBZ) has been widely used in agricultural production to control fruits and vegetables diseases, but it can also destroy the human endocrine system. Therefore, sensitive detection of CBZ has attracted increasing attention worldwide. In this study, Pd nanoparticles (Pd NPs) decorated on CdS microsphere (Pd NPs/CdS) was prepared by the in-situ photoreduced method, and based on the surface plasmon resonance (SPR) effect of noble metal and Schottky junction between Pd nanoparticles (Pd NPs) and CdS microsphere, the photocurrent after introducing Pd NPs is 7.7 times higher than that of bare CdS microsphere. In view of the outstanding photoelectrochemical (PEC) performance of Pd NPs/CdS and the high specificity of the aptamer, the as-fabricated PEC aptasensor for CBZ detection possesses the excellent detection performance including a broad linear ranging from 1.0 × 10−12 to 1.0 × 10−6 mol/L as a low detection limit of 3.3 × 10−13 mol/L (S/N = 3). Furthermore, the PEC aptasensor was used for determination of lettuce samples from actual agricultural products with satisfactory results.

Photocatalytic Chemoselective Transfer Hydrogenation of Quinolines to Tetrahydroquinolines on Hierarchical NiO/In2O3–CdS Microspheres

Photocatalytic Chemoselective Transfer Hydrogenation of Quinolines to Tetrahydroquinolines on Hierarchical NiO/In₂O₃–CdS Microspheres

A photocatalyst foam for superior visible-light photocatalytic hydrogen evolution

A photocatalyst foam is developed by growing high-density CdS microspheres on Ni2P nanolayer-modified Ni foam (NF) for efficient visible-light-driven photocatalytic H2 evolution.

Interfacing CdS particles on Ni foam as a three-dimensional monolithic photocatalyst for efficient visible-light-driven H2 evolution

Solar photocatalytic water splitting using particulate semiconductors has been valued as a potentially scalable way for the production of clean H2 energy, yet the performances of the powder-suspension systems are constrained by insufficient utilization of light energy and tedious recycling of photocatalyst particles. Here, we present a high-performance photocatalytic H2 evolution using a visible-light-driven CdS-based monolithic photocatalyst with three-dimensional (3D) heterostructure. The monolithic photocatalyst is fabricated by firmly growing CdS microspheres on a Ni(OH)2 nanosheet-modified Ni foam (NF) (denoted as CdS-NiSx/NF) via a simple hydrothermal process. The structure and component synergy endows the monolithic CdS-NiSx/NF photocatalyst advantageous features including high-density CdS microspheres for visible light harvesting, multiple heterojunction interfaces for efficient electron-hole separation, and abundant interfacial NiSx active sites for efficient H2 evolution reaction (HER). Upon visible light irradiation, the monolithic CdS-NiSx/NF photocatalyst exhibits an outstanding photocatalytic H2 evolution activity with an enhanced rate of 6.2 mmol·h−1 g−1CdS, which is 6 times higher than that of the suspended CdS powder. In addition, the structural integrity of the CdS-NiSx/NF enables a good stability for H2 evolution over a 30 h reaction. This monolithic photocatalyst is scalable in preparation and compatible for device fabrication, which offers great potentials for applications in solar cells, photoelectrocatalysis, and electrocatalysis.

Unique CdS@MoS2 Core Shell Heterostructure for Efficient Hydrogen Generation Under Natural Sunlight

The hierarchical nanostructured CdS@MoS2 core shell was architectured using template free facile solvothermal technique. More significantly, the typical hexagonal phase of core CdS and shell MoS2 has been obtained. Optical study clearly shows the two steps absorption in the visible region having band gap of 2.4 eV for CdS and 1.77 eV for MoS2. The FESEM of CdS@MoS2 reveals the formation of CdS microsphere (as a core) assemled with 40–50 nm nanoparticles and covered with ultrathin nanosheets of MoS2 (Shell) having size 200–300 nm and the 10–20 nm in thickness. The overall size of the core shell structure is around 8 µm. Intially, there is a formation of CdS microsphre due to high affinity of Cd ions with sulfur and further growth of MoS2 thin sheets on the surface. Considering band gap ideally in visible region, photocatalytic hydrogen evolution using CdS@MoS2 core shell was investigated under natural sunlight. The utmost hydrogen evolution rate achieved for core shell is 416.4 µmole h−1 with apparent quantum yield 35.04%. The photocatalytic activity suggest that an intimate interface contact, extended visible light absorption and effective photo generated charge carrier separation contributed to the photocatalytic enhancement of the CdS@MoS2 core shell. Additional, the enhanced hole trapping process and effective electrons transfer from CdS to MoS2 in CdS@MoS2 core shell heterostructures can significantly contribute for photocatalytic activity. Such core shell heterostructure will also have potential in thin film solar cell and other microelectronic devices.

Hydrothermal synthesis of CdS sub-microspheres for photocatalytic degradation of pharmaceuticals

Visible light active CdS were synthesised through a hydrothermal method followed by evaluation of their efficiency in the photodegradation of acetaminophen and levofloxacin. The microspheres were characterised by various physico-chemical techniques such as SEM, UV–Vis, XRD and XPS. The microspheres of about 0.5 µm size were observed to have lower band gap energy of about 2.26 eV. XPS analysis confirmed the formation of impurity-free CdS microspheres. Photocatalytic degradation studies using visible light from LEDs (455 nm) showed high degradation of the two drugs. Up to 85% of the acetaminophen and 70% of the levofloxacin were degraded in 240 min. CdS microspheres are promising visible light active photocatalyts for the degradation of pharmaceuticals such as acetaminophen and levofloxacin in water.

Fabrication of novel Z-scheme InVO4/CdS heterojunctions with efficiently enhanced visible light photocatalytic activity

Novel Z-scheme InVO4/CdS heterojunction photocatalysts have been successfully synthesized for the first time via a microwave-assisted process, followed by a mild hydrothermal method. The crystal structures, morphologies and sizes, chemical compositions and optical properties of the prepared photocatalysts were characterized via X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS), and photocurrent measurements. Results showed that the prepared InVO4/CdS heterojunctions were composed of about 15 nm InVO4 nanoparticles and 1.5 μm CdS microspheres, and all heterojunctions exhibited good photoabsorption in the visible light region. The photocatalytic activity of the obtained samples was carefully evaluated via the degradation of rhodamine B (RhB) and ciprofloxacin (CIP) under visible light irradiation (λ > 420 nm). Compared to that of bare InVO4 and CdS, the InVO4/CdS heterojunctions exhibited significantly enhanced photocatalytic activity for RhB and CIP degradation. Moreover, the 40 wt% InVO4-coupled CdS composite displayed the highest catalytic efficiency for RhB photodegradation, which is about 59.4 and 4.8 times higher than that of pure InVO4 and CdS, respectively. In addition, the active species trapping experiment and electron spin resonance (ESR) measurement demonstrated that h+ and ˙O2− radicals were the predominant active species in the photocatalytic reaction process. Furthermore, the possible enhanced photocatalytic mechanism of InVO4/CdS heterojunctions was also proposed based on the band position measurements and ESR analysis.

Synthesis of urchin-like Fe3O4@SiO2@ZnO/CdS core–shell microspheres for the repeated photocatalytic degradation of rhodamine B under visible light

Magnetically retrievable Fe3O4@SiO2@ZnO/CdS microspheres with a well-designed core–shell structure and excellent visible-irradiation photocatalytic performance were successfully synthesized.

Fabrication and excellent visible-light-driven photodegradation activity for antibiotics of SrTiO3 nanocube coated CdS microsphere heterojunctions

A new heterojunction, CdS/SrTiO3, was synthesized via a two step hydrothermal route and designed to decontaminate hazardous wastewater containing antibiotics under visible light irradiation.

Synthesis and photocatalytic activity of hollow CdS microspheres

Hollow CdS microspheres have been successfully synthesized via a template-free solvothermal process at a 1 : 1 Cd2+-to-S2− molar ratio.

Development of CdS Nanostructures by Thermal Decomposition of Aminocaproic Acid-Mixed Cd-Thiourea Complex Precursor: Structural, Optical and Photocatalytic Characterization.

The present work deals with two different CdS nanostructures produced via hydrothermal and solvothermal decompositions of aminocaproic acid (ACA)-mixed Cd-thiourea complex precursor at 175 °C. Both nanostructures were extensively characterized for their structural, morphological and optical properties. The powder X-ray diffraction characterization showed that the two CdS nanostructures present a wurtzite morphology. Scanning electron microscopy and energy-dispersive X-ray characterizations revealed that the hydrothermal decomposition produced well-shaped CdS flowers composed of six dendritic petals, and the solvothermal decomposition produced CdS microspheres with close stoichiometric chemical composition. The UV-vis absorption and photoluminescence spectra of CdS dendritic flowers and microsphere nanostructures showed that both nanostructures present a broad absorption between 200 and 700 nm and exhibit strong green emissions at 576 and 520 nm upon excitations at 290 nm and 260 nm, respectively. The transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) characterizations confirmed that CdS microspheres were mesoporous and were composed of small nanocrystals. A possible growth mechanism in the formation of the CdS nanostructures was proposed based on morphology evolution as a function of the reaction time. Furthermore, the as-synthesized CdS nanostructures were found to exhibit highly efficient photocatalytic activities for the degradation of methyl orange (MeO) and rhodamine B (RhB) dyes.

A bifacial quantum dot-sensitized solar cell with all–cadmium sulfide photoanode

Pursuit of a high power conversion efficiency and reduction of electricity-generation cost has been a persistent objective for quantum dot-sensitized solar cells (QDSSCs). We present here the fabrication of a QDSSC comprising a nanoflower-structured CdS anode, a liquid electrolyte having S2−/Sn2− redox couples, and a transparent CoSe counter electrode. Nanoflower-structured CdS anodes are prepared by a successive ionic layer adsorption and reaction (SILAR) method and subsequently hydrothermal strategy free of any surfactant or template. The CdS nanoparticles synthesized by a SILAR method act as “seed crystal” for growth of CdS nanoflowers. The average electron lifetime is markedly elevated in nanoflower-structured CdS anode in comparison with CdS nanoparticle or nanoporous CdS microsphere anode. Herein, we study the effect of synthesis method on CdS morphology and solar cell's photovoltaic performance, showing a power conversion efficiency of 1.67% and 1.17% for nanoflower-structured CdS QDSSC under front and rear irradiations, respectively.

Woolen bun shaped CdS microspheres enfolded 1D nanowires for the superior photooxidation of dyes: A comparative case study

Woolen bun shaped CdS microspheres (2–5μm) wrapped by highly crystalline one dimensional CdS nanowires (length=8–10μm and diameter ∼80nm) are synthesized via anodic alumina membrane to achieve the best photoactivity for the decomposition of rhodamine B (50μM) and methylene blue (20μM) dyes using sunlight (50mWcm−2) irradiations. The higher number of surface exposed molecules for improved interactions with dye molecules in CdS nanowires led to its excellent photocatalytic performance over its spherical [cubic (∼12 nm) and hexagonal (∼15 nm) phase] and rod like (170 nm × 10 nm) morphology. Though of having less surface area (35.55 < 76 m2g−1) than nanorods, the crystalline structure with least surface defects, higher spectral response to absorb more light for multiple generation of charge carriers (e−–h+), and their superior delocalization for better charge separation as evidenced from its maximum (>80%) photoluminescence quenching and higher photoexcited charge carrier relaxation lifetime (3.6 ns) seems to be the cause of its outstanding performance. Many intermediate products and nearly linear increase in CO2 production are quantified during rhodamine B degradation by CdS nanowires under different time periods of sunlight irradiation.

Preparation and enhanced photocatalytic activity of CdS@RGO core–shell structural microspheres

Reduced graphene oxide (RGO) wrapped CdS microspheres with enhanced photocatalytic activity were successfully synthesized via a two-step hydrothermal method. The as-prepared samples were carefully characterized by X-ray diffraction, scanning electron microscopy and Raman spectrometer. The photocatalytic activity of the as-prepared samples was evaluated by photocatalytic decolorization of Rhodamine B (RhB) under visible light irradiation. Due to its large surface area and stepwise structure of energy level, which result in the efficiently enhancing of the adsorption performance of dye molecules and suppressing of the charge recombination of photocatalytst, a remarkably enhanced degradation rate of RhB dye about 95.2% within 50 min has been observed. In addition, the introduction of the graphene shell could effectively protect the internal CdS microsheres from photocorrosion, and the composite showed an excellent recyclability property for its photocatalytic applications.

Template-free syntheses of CdS microspheres composed of ultrasmall nanocrystals and their photocatalytic study

A one-pot, template-free, solvothermal method for synthesizing CdS microspheres composed of ultrasmall (∼2 nm) nanocrystals without and with the use of MCE-capping agent has been developed. The photocatalytic activity of the microspheres for degradation of MO under UV and natural sunlight irradiation has been compared.

Synthesis of hollow CdS micro-/nanospheres by CoSP technique and their visible light photocatalytic activities

CdS hollow micro-/nanospheres with high yield, purity, and photocatalytic property have been successfully synthesized by a continuous spray pyrolysis (CoSP) technique. The experimental conditions mainly the temperature and the nature of solvent are found to influence the creation of hollow spheres. The synthesized products have been characterized by X-ray powder diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), UV–vis and photoluminescence spectra. The XRD analysis confirmed the hexagonal crystal structure of the CdS microspheres supported by the measured lattice spacing from HR-TEM. The effects of synthesis temperature and the electric field applied during the spray on the formation of hollow spheres and their visible light photocatalytic properties are reported. Photodegradation of methylene blue (MB) dye under visible light was used to evaluate the performance of these CoSP made CdS micro-/nanospheres. The MB photodegradation efficiency was maximum, ∼90% in 2h, for CdS microspheres prepared at 500°C. The importance of hollow morphology over solid morphology is also proven; the hollow sphere sample (CdS5) is about twice efficient than solid sphere sample (CdS7). The results show that the CoSP method is a simple and inexpensive technique for preparing highly photo-active CdS hollow spheres which can be extended to prepare other sulphide and oxide hollow spheres at a large scale. Typically 100mg of the powder can be prepared from ∼100ml of spray solution.

Photocatalytic degradation of dyes by CdS microspheres under near UV and blue LED radiation

Nanostructured CdS microspheres were prepared by hydrothermal synthesis and used as photocatalyst in the degradation of dyes under near UV and blue LED radiation. Nearly complete degradation of methylene blue, phenol red and methyl red was achieved in 3h. Catalytic performance of the microspheres remained unchanged during five recycling steps. Different modification methods were tested to prevent photocorrosion of the CdS particles. Using glucose as protecting agent gave the most promising results. Furthermore, photocatalysis under LED radiation tested in this study showed quite good energy efficiency, which makes this method economically appealing.

Synthesis of CdS cauliflower-like microspheres via a template-free hydrothermal method

The cauliflower-like CdS microspheres consisting of the nanoblocks were prepared via one step template-free approach employing a hydrothermal process using CdCl2·2½H2O and Na2S2O3·5H2O as precursors in the aqueous solution. The products were characterized by scanning electron microscopy(SEM) indicated that the flower-like CdS microspheres with diameters of about 3µm were constructed with CdS nanoparticles. The products also were characterized by powder X-ray diffraction(XRD) and the crystalline sizes are <100nm according to the Scherrer formula. Optical investigation showed that the obtained CdS microspheres have an UV–vis absorption at about 610nm. And the possible formation process of the flower-like CdS microspheres is proposed.