CdS Nanocomposites Research Articles

Hydrothermal synthesis of ZnO–CdS nanocomposites: Structural, optical and electrical behavior

ZnO–CdS nanocomposites with three different molar ratios of 25:75, 50:50 and 75:25 were synthesized by simple hydrothermal technique. Powder X-ray diffraction patterns confirmed the phase formation of ZnO and CdS in ZnO–CdS nanocomposites. The calculated crystallite size was found in the range of 33–38 nm and 15–21 nm for ZnO and CdS respectively. HRSEM images revealed flake-like morphology for all samples. Energy dispersive X-ray spectra confirmed the presence of all the elements. The estimated optical bandgap was found in the range of 3.71–3.35 eV. IR spectra confirmed the formation of stretching vibration in ZnO and CdS. Dielectric analysis was performed in order to study Ac conductivity, dielectric constant and dielectric loss. Photoconductivity studies revealed that ZnO–CdS nanocomposites material exhibited sound photo-response characteristics.

NiSe2 as Co-Catalyst with CdS: Nanocomposites for High-Performance Photodriven Hydrogen Evolution under Visible-Light Irradiation.

One-dimensional NiSe2 /CdS nanocomposites (NCs), with NiSe2 nanoparticles (NPs) integrated onto the surface of CdS nanowires (NWs) were designed and fabricated through a two-step in situ solvothermal method. Density functional theory (DFT) calculations showed that NiSe2 plays an important role in enhancing photocatalystic hydrogen (H2 ) production when coupled with CdS catalyst, which arises from 1) the contribution of Ni 3d and Se 4p orbitals to the electronic structures and 2) the charge redistribution at the interface region of the heterostructure results in efficient promotion of the charge transfer and separation of the photogenerated electron-hole pairs. Under visible-light illumination (λ≥400 nm), the NCs showed improved photocatalytic H2 -generation activity in the presence of lactic acid. The peak value of 7610.1 μmol h-1 g-1 for H2 production was achieved with an apparent quantum efficiency (AQE) of 41.68 % when the Ni/Cd ratio was set to 10 %, which was approximately 48 times higher than that of bare CdS NWs. Photoelectrochemical measurements also confirmed the pivotal role of NiSe2 in the improvement of the H2 -evolution performance of NiSe2 /CdS NCs, which is consistent with the DFT investigations.

The effect of adding CoFe2O4–CdS nanoparticles on the mechanical properties of rice husk ash epoxy composite: an experimental approach

In this paper, first, cobalt ferrite and cadmium sulfide nanostructures were synthesized through precipitation method. Thereafter, CoFe2O4 nanocomposite as core–shell structure with magnetic cobalt ferrite core and cadmium sulfide shell was synthesized through chemical method. Afterward, the effect of the synthesized nanocomposites along with rice husk ash microparticles (RHAMPs) on the mechanical properties of epoxy resin (EP) has been investigated. Epoxy resin (Epikote 828) and polyamine hardener have been used to prepare the nanocomposite samples. CoFe2O4–CdS nanocomposites with weight percentages of 0, 0.5, 1, and 2% mixed with 3% of rice husk ash microparticles (RHAMPs) were distributed inside the epoxy resin (EP). The prepared products were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), Fourier transform infrared (FTIR), and alternating force gradient magnetometer (AFGM). The mechanical properties of the epoxy nanocomposites/RHAMPs were also determined using uniaxial tensile standard and three-point bending tests. The results associated with the mechanical tests also showed improvement in tensile modulus, bending modulus, and strength of epoxy resin by adding nanoparticles along with rice husk ash to the epoxy matrix.

Electrochemical investigation of hybridized WO3–CdS semiconducting nanostructures prepared by microwave-assisted wet chemical route for supercapacitor application

Herein, we are reporting the enhanced electrochemical performance of hybridised WO3–CdS nanocomposites prepared by microwave assisted wet chemical route without post synthesis of heating for different wt% of CdS (2 wt%, 4 wt% and 6 wt%) loading with WO3. Then, the end products were characterized by various techniques to evaluate their structural and morphology, thermal, optical, and electrochemical properties. From the XRD analysis, the orthorhombic and monoclinic structure of WO3 and hexagonal phase of CdS were observed and the average crystalline size is calculated as ± 19 nm. The microscopic examination such as SEM images showed smooth and tiny particle and HRTEM images showed rod shape morphology in the as-prepared particle. The presence of W and Cd elements are confirmed by EDAX analysis. The existences of functional groups related to W and Cd are analyzed by FTIR investigation and confirmed the chemical bonding nature. Thermal (TGA/DTA) analysis showed that as-prepared structures are stable up to 450°C temperature. The electrochemical investigations have been carried out, and their enhanced specific capacitances were calculated as 44 F/g for pure WO3 (a) nanostructures and 48, 170, and 172 F/g correspondingly for the hybridised WO3–CdS (b, c, d) nanocomposites.

Comparative Study of EPR and Optical Properties of CdS, TiO2 and CdS-TiO2 Nanocomposite

An economical chemical route is used to synthesize a titanium oxide-based nanocomposite (NC) which has properties that may help to develop photocatalysts with improved efficiency in the visible region of solar light. Investigation of opto-electronic properties has been carried out for a CdS, TiO2 and CdS-TiO2 NC at room temperature. Structural properties of the CdS and TiO2 nanoparticles and the CdS-TiO2 NC were investigated using x-ray diffraction and transmission electron microscopy techniques. How incorporation of CdS nanoparticles affects the structural properties of pure TiO2 was also studied. Change in optical behavior was compared using UV–visible and photoluminescence spectra, and the presence of residual functional groups were indicated by Fourier-transform infrared analysis of the samples. The measurement of band levels was carried out by cyclic voltammetry (CV) and the band gap estimated from UV–visible was compared to that obtained by CV. The electron paramagnetic resonance technique was used for the investigation of the electronic properties of the samples.

Enhanced photocatalytic degradation of methylene blue dye using CuS[sbnd]CdS nanocomposite under visible light irradiation

The inorganic nanoparticles based semiconductor photocatalyst has attracted widespread attention for the practical applications in sustainable energy and environmental remediation due to its low cost, eco-friendly, high efficiency and ease of process. CuS, CdS and CuSCdS nanocomposite photocatalysts have been successfully synthesized by a simple hydrothermal approach. The phase purity, composition and surface morphology of as synthesized nanomaterials were characterized using various analytical techniques. The photocatalytic activities of the as-prepared materials have been evaluated by the degradation of methylene blue (MB) dye in the presence of hydrogen peroxide (H2O2) which served as an oxidant under visible light irradiation. MB dye (10 ppm) was degraded by about 80%, 59% and 99.97% for CuS, CdS and CuSCdS nanocomposite respectively at 10 min. The results demonstrate that CuSCdS nanocomposite exhibited excellent photocatalytic activity as compared to the CuS and CdS is which mainly attributed to large surface area, narrow band gap, high adsorbing capacity of the dye and also low recombination of the photo-generated electrons and holes. Further, electrochemical impedance (EI) measurement revealed that as prepared CuSCdS nanocomposite suggested that as compared to CuS and CdS, the CuSCdS nanocomposite exhibits rapid migration of photo-induced charge carriers. In addition, the CuSCdS nanocomposite demonstrated that good stability towards photocatalytic degradation even after repeated usage. Finally, a suitable photocatalytic reaction mechanism has been proposed to indicate the photocatalytic performance of the nanocomposite.

Voltammetric immunoassay of human IgG based on the release of cadmium(II) from CdS nanocrystals deposited on mesoporous silica nanospheres.

The authors describe a nanocomposite that was obtained by in-situ deposition of CdS nanocrystals on mesoporous silica nanospheres (MSNs), and its use in an electrochemical immunoassay of human immunoglobulin G (HIgG). The MCN/CdS nanocomposite was covalently modified with the antibodies against HIgG and then employed in a voltammetric immunoassay at antibody-functionalized magnetic beads. Through sandwich immunoreaction, the MCN/CdS nanoprobes are quantitatively captured onto the magnetic beads where numerous Cd(II) ions are released in an acidic solution. The Cd(II) can be detected by anodic stripping voltammetry at a typical working potential of -0.78V (vs. Ag/AgCl). In combination with the high loading of CdS on MSNs, the use of the stripping voltammetric analysis renders the method high sensitivity. A wide linear range varying from 0.01 to 100ngmL-1 is obtained for HIgG detection with a lower detection limit at 2.9pgmL-1. In addition, the preparation of the nanoprobe is inexpensive. The magnetic bead-based assay does not require complex manipulations. Therefore, this method is deemed to possess a wide scope in that it may be applied to other immunoassays. Graphical abstract Graphical Abstract contains poor quality and small text inside the artwork. Please do not re-use the file that we have rejected or attempt to increase its resolution and re-save. It is originally poor, therefore, increasing the resolution will not solve the quality problem. We suggest that you provide us the original format. We prefer replacement figures containing vector/editable objects rather than embedded images. Preferred file formats are eps, ai, tiff and pdf.A TIFF file at 900 dpi resolution of the Graphical Abstract has been attached via this online system. Schematic presentation of the preparation of the mesoporous silica nanosphere (MSN)/CdS nanocomposite for the electrochemical immunoassay of human IgG at magnetic beads. The high decoration of CdS on MSN and the stripping voltammetric analysis of Cd(II) ions render the method high sensitivity.

Characterization of CBD–CdS nanocrystals doped with Co2+

Co-doped CdS nanofilms are synthesised by chemical bath deposition growth technique at the temperature of 60 ± 2 °C. The cobalt molar fraction was ranged from 0 ≤ x ≤ 5.47, which was determined by energy-dispersive X-ray spectroscopy. The X-ray diffraction shows that the nanofilms are of CoS–CdS nanocomposites with individual CdS and CoS crystalline planes. The Co-doped CdS crystalline phase was zinc-blende that was determined by X-ray diffraction and confirmed by Raman spectroscopy. The average grain size of the CdS films was ranged from 2.56 to 1.67 nm that was determined by Debye–Scherrer equation from ZB (111) direction and it was confirmed by Wang equation and high resolution transmission electron microscopy (HRTEM). Raman scattering shows that the CdS lattice dynamics is characteristic of a bimodal behaviour, in which the first optical longitudinal mode denotes the characteristic peak at 305 cm−1 of the CdS nanocrystals that is associated with the cobalt incorporation. Nanofilms present two main bandgaps at ~ 2.56 and 3.80 eV, which are attributed to single CdS and quantum-confinement due to nanocrystals size. The increase in band gap with increase in cobalt concentration suggests intermetallic compound of CoS (Eg = 1.60 eV) with CdS (Eg = 2.44 eV). The CdS nanocrystals size was ranged from 2.46 to 1.81 nm that was determined from ZB (111) direction by Debye–Scherrer equation and confirmed by the Wang equation. The room-temperature photoluminescence of the Co-doped CdS presents well-resolved radiative bands associated to structural defects and with the quantum-confinement. For the Co-doped CdS the photoluminescence intensity increases indicate a high-passivation of the nanocrystals.

Mutual effect of extrinsic defects and electronic carbon traps of M-TiO2 (M = V, Co, Ni) nanorod arrays on photoexcited charge extraction of CdS for superior photoelectrochemical activity of hydrogen production

Understanding the photoexcited charge carrier dynamics such as separation, transportation and extraction in smart hybrid nanocomposites is the key to high performance solar cells. Nanocomposites possess advantage of broader solar absorption with their fast photoexcited charge separation and transportation but their use as photocorrosion-stable material is yet to be explored. Also, bulk and surface defects in individual components of the nanocomposites boost the efficiency of the solar cells, despite of the fact the recombination of the photoexcited charges at the interfaces lead to a substantial loss of charges and realizing a big challenge. Herein, the extrinsic defects like bulk and surface defects are induced by transition metal (M = V, Co, Ni) doping of M − TiO2 nanorod arrays. Consequently, the hydrothermal synthesis method offers the tuning of the carbon trapping states depending upon the type of the metal doped in M − TiO2 that decelerates the charge carrier dynamics in the M-TiO2/CdS (M = V, Co, Ni) nanocomposites with the increase in the amount of carbon. Excellent charge extraction is observed in VTiO2 (4% carbon) from its CdS sensitizer with photocurrent density of 2.06 mA/cm2 than NiTiO2 (14.6% carbon), TiO2 (18.94% carbon) and CoTiO2 (39.2% carbon) with photocurrent densities of 1.83, 1.46 and 1.34 mA/cm2 at 0 V versus Ag/AgCl under 100 mW/cm2 light intensity, respectively. This shows primary dependence of photoexcited charge dynamics upon the density of the carbon trapping states to be least while secondary dependence upon the density of the extrinsic defects in M − TiO2 to be maximum. This work creates a paradigm for future studies to have a broader insight of the photocatalyst's overall functioning to boost the efficiencies in solar cells by controlling the amount of electronic carbon traps during the synthesis of a large class of inorganic semiconductor photocatalysts.

One-step hydrothermal synthesis of MoS2/ CdS nanocomposite and study of structural, photocatalytic, and optical properties of this nanocomposite

In this paper, one-step hydrothermal synthesis of CdS/ MoS2 nanocomposite is proposed as a suitable option, with high photocatalytic property, for application in solar cells’ structure. Also, UV–vis spectroscopy was performed for the synthesized nanoparticles and nancomposites, which showed that the CdS coverage synthesized on the surface of MoS2 creating CdS/ MoS2 nanocomposite, causes the nanocomposite’s absorption to the shift towards the lower wavelengths, leading to the increase in the composite’s band gap comparing to MoS2. Moreover, XRD and EDX analyses confirmed the successful synthesis, while the morphology of the prepared materials were investigated by FESEM and HRTEM.

Application of modified screen-printed carbon electrode with MWCNTs-Pt-doped CdS nanocomposite as a sensitive sensor for determination of natamycin in yoghurt drink and cheese

In this study a novel method was developed to fabricate a screen-printed carbon electrode (SPCE) modified by a composition of multi-wall carbon nanotubes (MWCNTs) and Pt-doped CdS nanoparticles(Pt-CdS/MWCNTs/SPCE). A simple microwave-assisted hydrothermal approach was employed in the synthesis of Pt-doped CdS nanoparticles. It is demonstrated that the modified electrode is a promising sensor for the determination of natamycin under the optimum conditions. Electrochemical behavior of the electrode was studied using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The latter showed a linear relationship between natamycin concentration and anodic peak in the concentration ranges from 0.2 μM to 70.0 μM with a detection limit of 0.12 μM under the optimum conditions. The fabricated sensor displayed an excellent stability, sensitivity and good reproducibility in determination of natamycin. The results suggested that the sensor is a promising one for a rapid determination of natamycin in commercial yoghurt drink and cheese samples in routine analysis with an excellent recovery and without the interferences of coexisting substances.

Synthesis of rGO/TiO2/CdS Nanocomposites and its Enhanced Photoelectrochemical Performance in Determination of Parathion-Methyl

A photoelectrochemical (PEC) sensor for the determination of organophosphate pesticides (OPs) was developed based on rGO/TiO2/CdS photoactive nanomaterials. The rGO/TiO2/CdS nanocomposites were prepared by solvothermal method and electrochemical deposition technique successively. The morphologies and structures of the as-prepared nanocomposites were extensively investigated by SEM and XRD. In alkaline condition, p-nitrophenol as the hydrolysate of parathion-methyl (PM) could be obtained by a simple hydrolyzation process. Under optimal conditions, the rGO/TiO2/CdS NPs modified ITO electrode exhibited a good PEC performance toward the hydrolysate of PM. The photocurrent intensity was enhanced with the increase of the concentration of the hydrolysate of PM. The proposed PEC method could detect PM in the range from 0.05[Formula: see text]nmol L[Formula: see text] to 10[Formula: see text]nmol L[Formula: see text] with a detection limit of 0.02[Formula: see text]nmol L[Formula: see text] ([Formula: see text]). Thus, the excellent performance of the rGO/TiO2/CdS nanocomposites serve as the matrix of the sensor, which provides a new way for the fabrication of high-sensitivity PEC sensing system.

A label-free photoelectrochemical biosensor for urokinase-type plasminogen activator detection based on a g-C3N4/CdS nanocomposite

Herein, we established a novel ultrasensitive photoelectrochemical biosensor for detecting urokinase-type plasminogen activator (u-PA), based on a g-C3N4/CdS nanocomposite. The prepared nanocomposite was characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, ultraviolet–visible absorption spectroscopy, and Fourier transform infrared spectroscopy, thus indicating that the nanocomposite was prepared successfully. In the typical process, the prepared nanocomposite was deposited on the surface of a bare FTO electrode. After being air-dried, the g-C3N4/CdS nanocomposite modified electrode was successively incubated with antibody against urokinase-type plasminogen activator and the blocking agent BSA to produce a photoelectrochemical biosensor for u-PA. In the presence of target u-PA antigen, the photocurrent response of the prepared biosensor electrode decreased significantly. The proposed novel photoelectrochemical biosensor exhibited good sensitivity, specificity, and reproducibility for u-PA detection, and a low detection limit of 33 fg mL−1, ranging from 1 μg mL−1–0.1 pg mL−1. The proposed strategy should provide a promising method for detection of other biomarkers.

Noble metal-free 0D–1D NiSx/CdS nanocomposites toward highly efficient photocatalytic contamination removal and hydrogen evolution under visible light

The development of stable noble metal-free photocatalysts with efficient separation and transportation of the photogenerated electrons-holes is of crucial importance for promoting the application of photocatalysis technology. Herein, we propose an electron transfer strategy by reasonable design and fabrication of novel 0D NiSx nanosheets as a co-catalyst on the surface of 1D CdS nanorods (CdS-NRs) to enhance photocatalytic hydrogen evaluation and contamination (Cr(vi), rhodamine B and bisphenol A) removal in water. Under visible light irradiation, the 0D-1D NiSx/CdS-NR nanocomposite with 1.5% NiSx loading gave a hydrogen evolution rate of 5.98 mmol h-1 g-1, which is about 5.3 times and 1.9 times higher than that of the native CdS-NRs and the optimal 1% Pt/CdS-NRs, respectively. Notably, good stability in the recycling test and a high apparent quantum efficiency of about 69.9% at 420 nm were also obtained. The 1.5% NiSx/CdS-NRs exhibited enhanced photocatalytic contamination degradation efficiency of about 2 times higher than pure CdS-NRs. In this hybrid photocatalyst, 0D NiSx nanosheets came into intimate interfacial contact with the surface of 1D CdS-NRs and played a similar role as noble metals, which could effectively improve the separation, transportation efficiencies and lifetime of photogenerated charge, and thus enhance the photocatalytic performance of CdS-NRs with more efficient conversion of solar energy. This work shows not only a possibility for the utilization of noble metal-free NiSx as a co-catalyst in the photocatalysis, but also provides new insight into the design and fabrication of high-performance composite photocatalysts (such as NiSx/g-C3N4 and NiSx/Zn3In2S6).

Synthesis and enhanced photocatalytic activity of g- $$\hbox {C}_{3}\mathrm{N}_{4}$$ C 3 N 4 hybridized CdS nanoparticles

The highly effective g- $$\hbox {C}_{3}\hbox {N}_{4}$$ hybridized CdS photocatalysts were synthesized via a successive calcination and hydrothermal process. The as-prepared photocatalysts were characterized by X-ray powder diffraction, transmission electron microscopy and UV–Vis diffuse reflectance spectroscopy. The photocatalytic performance of the $$\hbox {C}_{3}\hbox {N}_{4}$$ /CdS nanocomposites was evaluated by the photodegradation of RhB under visible light irradiation. The results showed that photocatalytic ability of the $$\hbox {C}_{3}\hbox {N}_{4}$$ /CdS nanocomposites was higher than that of pure $$\hbox {C}_{3}\hbox {N}_{4}$$ and CdS. The enhanced photocatalytic activity could be attributed to the high separation efficiency of the photo-excited electron-hole pairs. A possible mechanism of the photocatalytic degradation of RhB on $$\hbox {C}_{3}\hbox {N}_{4}/$$ CdS nanocomposites was also proposed.

One-Step Solvothermal Synthesis of Petalous Carbon-Coated Cu+-Doped CdS Nanocomposites with Enhanced Photocatalytic Hydrogen Production.

Metal ion doping and nanocoating a CdS photocatalyst have been proven to be effective strategies to inhibit photocorrosion and improve photocatalytic performance. In this study, carbon-coated Cu+-doped CdS nanocomposites (C-Cu-CdS) with a stable petalous structure and highly uniform size distribution were successfully synthesized via a facile one-step solvothermal method. Both Cu+ doping and carbon coating to the CdS photocatalyst are realized in this one-step strategy. Benefiting from the unique core-shell structure and metal ion doping, the as-prepared C-Cu-CdS catalyst exhibits significantly enhanced photostability and visible-light-driven photocatalytic efficiency. For an optimal Cu+ doping percentage of 1.0%, an average hydrogen production rate of 2796 μmol h-1 g-1 and an apparent quantum efficiency of 16.0% at a wavelength of 420 nm was observed, the latter of which is nearly 9.3 times higher than that of the carbon-coated CdS product without Cu+ doping. The origin of the improved photocatalytic activity is systematically investigated by examining the effects of Cu+ doping.

Hydrothermal Carbonation Carbon-Coated CdS Nanocomposite with Enhanced Photocatalytic Activity and Stability

Herein, a novel CdS nanocomposite is fabricated by a facile one-pot hydrothermal method assisted by glucose and polyvinylpyrrolidone (PVP). The as-prepared CdS is coated with a thin layer, which is determined to be hydrothermal carbonation carbon (HTCC) mainly containing semiconductive polyfuran. The as-prepared HTCC-coated CdS shows superior photocatalytic activity for the degradation of Rhodamine B (RhB) under visible light irradiation (λ ≥ 420 nm). The optimum sample (glucose content of 0.1 g) shows a degradation rate four-times that of pure CdS reference. Moreover, it also shows an improved stability, and the activity can be maintained at 96.2% after three cycles of recycling. The enhanced photocatalytic activity and stability of nanocomposite can mainly be attributed to: (i) The addition of PVP in the reaction solution can significantly increase the specific surface area of CdS and thus offer more active sites; (ii) The HTCC in the nanocomposite can expand the range of light absorption; (iii) The HTCC layer can form a heterojunction with CdS and improve the charge separation and transfer.

In situ preparation of few-layered WS2 nanosheets and exfoliation into bilayers on CdS nanorods for ultrafast charge carrier migrations toward enhanced photocatalytic hydrogen production

Transition-metal dichalcogenides (TMD) have emerged as a fascinating new class of noble-metal-free materials for photocatalytic hydrogen evolution from the water. Recently, numerous approaches have been established to develop single- or few-layered TMDs to improve their physical properties. Although WS2 has a higher intrinsic electric conductivity than the MoS2 analogue, most photocatalytic studies using TMD have focused on the nanocomposite using MoS2 as a co-catalyst. In the present study, we synthesized in situ and highly efficient few-layered WS2 nanosheets and exfoliated them to bilayers (i.e., ultrathin) on CdS nanorods (UWC) by a simple ultrasonication process. The optimized UWC-6 photocatalyst exhibits a tremendous rate of H2 production of ∼185.79mmolh−1g−1 using simulated solar light irradiation, with a quantum efficiency of 40.5%. The performance of this photocatalyst is 33 times greater than that of pristine CdS and 3.5-fold greater than that of few-layered WS2–CdS nanocomposite (BWC) photocatalysts. The ultrathin WS2 nanosheets are long and discontinuously stacked along the CdS nanorods, with high coverage of mixed-phase layers. This combination leads to the efficient photogeneration of charge carriers and enhances the surface shuttling properties of the photocatalyst for greater effective H2 production via active edge sites and superior intrinsic electrical conductivity. The H2 evolution rate reported here is much higher than for bulk or few-layered WS2-assisted CdS photocatalysts. To the best of our knowledge, this is the highest H2 production rate achieved by a WS2-based CdS photocatalyst by splitting water using simulated solar light irradiation.

A modified Z-scheme Er3+:YAlO3@(PdS/BiPO4)/(Au/rGO)/CdS photocatalyst for enhanced solar-light photocatalytic conversion of nitrite

Z-scheme structure is an effectively construction to improve the photocatalytic activity due to the excellent photo-generated electron-hole pairs separation efficiency. In this paper, the Er3+:YAlO3@(PdS/BiPO4)/(Au/rGO), (Au/rGO)/CdS and modified Z-scheme Er3+:YAlO3@(PdS/BiPO4)/(Au/rGO)/CdS photocatalysts were prepared by hydrothermal, ultrasonic dispersion, deposition-precipitation and ultrasonic-assisted methods. The prepared samples were characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectra (DRS), fourier transform infrared spectra (FT-IR), raman spectra and photoluminescence (PL) spectra. The photocatalytic activity of prepared samples were evaluated via photocatalytic conversion rate of nitrite under ultraviolet-light and simulated solar-light irradiations. Due to the enhanced separation efficiency of electron-hole pairs, the Er3+:YAlO3@(PdS/BiPO4)/(Au/rGO)/CdS exhibited excellent performance under both ultraviolet-light and simulated solar-light irradiation, reaching 94.59% and 91.25% conversion rates, respectively. Meanwhile, the effects of simulated solar-light irradiation time and corresponding reaction kinetics on photocatalytic conversion of nitrite were studied. Subsequently, the effects of electron and hole scavengers were investigated to further elaborate the possible mechanism. In addition, the study of used times showed that the prepared modified Z-scheme Er3+:YAlO3@(PdS/BiPO4)/(Au/rGO)/CdS nanocomposites can be effectively recycled without an apparent inactivation on photocatalytic activity. This research may provide a potential way by utilizing solar energy efficiently for converting nitrite and other contaminants released into the environment.

Photodeposited-metal/CdS/ZnO heterostructures for solar photocatalytic hydrogen production under different conditions

In this study, photocatalytic hydrogen production over metal-incorporated CdS and ZnO (M/CdS/ZnO) nanocomposites under simulated solar light illumination was investigated. M/CdS/ZnO samples were synthesized by photodepositing a metal into CdS/ZnO powders. All photocatalysts showed increased hydrogen production with an increase in the light exposure time. The M/CdS/ZnO samples exhibited better hydrogen production yields than the CdS/ZnO nanocomposites, which in turn showed higher hydrogen production yields than pure ZnO did. The hydrogen production yields of the CdS/ZnO samples increased as the CdS/ZnO weight ratio increased from 0.01 to 0.10. However, they decreased with further increases in CdS loading, although the light absorption edges of the CdS/ZnO samples were further extended to the visible region. Pt/CdS/ZnO and Pd/CdS/ZnO exhibited similar hydrogen production yields, which were higher than the Ni/CdS/ZnO yield. The hydrogen production yield of Pt (0.5%)/CdS/ZnO was higher than that of Pt (0.1%)/CdS/ZnO. Notably, the hydrogen production yield of CdS/Pt/ZnO was lower than that of Pt/CdS/ZnO. Among three different electron donors (Na2S + Na2SO3, methanol, and lactic acid solutions), the Na2S + Na2SO3 solution led to the highest hydrogen production yield. A tentative mechanism for photocatalytic hydrogen production over M/CdS/ZnO nanocomposites under solar light irradiation, using a Na2S + Na2SO3 solution as an electron donor, was proposed. In summary, M/CdS/ZnO photocatalysts can be utilized efficiently for photocatalytic hydrogen production with solar light exposure through proper control of operating parameters.