CdS Nanotubes Research Articles

Bimetallic PtNi nanozyme-driven dual-amplified photoelectrochemical aptasensor for ultrasensitive detection of sulfamethazine based on Z-scheme heterostructured Co9S8@In-CdS nanotubes

Antibiotics residues are still an important and noticeable issue, and realizing the ultra-sensitive, sample, and rapid detection of residual antibiotics in the environment is the basis for evaluating and monitoring the pollution status. Herein, a new bimetallic PtNi nanozyme-driven dual-amplified photoelectrochemical (PEC) aptasensor was developed for sulfamethazine (SMZ) assay based on the superior photosensitive material of Z-scheme heterostructured Co9S8@ In doped CdS nanotubes (Co9S8@In-CdS NTs). In this protocol, bimetallic alloyed nanotube PtNi was introduced as the mimic enzyme to instead of bio-enzyme for constructing of signal amplification strategy. On the basis of the outstanding photosensitivity of Co9S8@In-CdS NTs and highly catalytic property of PtNi nanozyme, the proposed PEC aptasensor exhibits a wide linear range of 0.05 pg mL–1 ~ 1.0 ng mL–1, and a low detection limit of 37.2 fg mL–1. This work put forwards a novel approach for the accurate analysis of antibiotics in the environment.

Enzyme-Photocatalyst Tandem Microrobot Powered by Urea for Escherichia coli Biofilm Eradication.

Urinary-based infections affect millions of people worldwide. Such bacterial infections are mainly caused by Escherichia coli (E. coli) biofilm formation in the bladder and/or urinary catheters. Herein, the authors present a hybrid enzyme/photocatalytic microrobot, based on urease-immobilized TiO2 /CdS nanotube bundles, that can swim in urea as a biocompatible fuel and respond to visible light. Upon illumination for 2 h, these microrobots are able to remove almost 90% of bacterial biofilm, due to the generation of reactive radicals, while bare TiO2 /CdS photocatalysts (non-motile) or urease-coated microrobots in the dark do not show any toxic effect. These results indicate a synergistic effect between the self-propulsion provided by the enzyme and the photocatalytic activity induced under light stimuli. This work provides a photo-biocatalytic approach for the design of efficient light-driven microrobots with promising applications in microbiology and biomedicine.

Photocatalytic Oxidation of 5-Hydroxymethylfurfural Selectively into 2,5-Diformylfuran with CdS Nanotube

Photocatalytic Oxidation of 5-Hydroxymethylfurfural Selectively into 2,5-Diformylfuran with CdS Nanotube

Hollow CdS nanotubes with ZIF-8 as co-catalyst for enhanced photocatalytic activity

Designing high-efficiency heterojunction photocatalysts for water splitting is an intriguing prospect in energy conversion. Herein, we successfully fabricated a CdS/ZIF-8 heterojunction system through a facile wet-chemically method, in which ZIF-8 nanoparticles were in-situ adhered on hollow CdS nanotubes. Due to the well-matched band structure and intimate interface contact in CdS/ZIF-8 hybrid structure, the interfacial charge separation in the established system was tremendously boosted. As a consequence, the established CdS/ZIF-8 heterojunction exhibited the optimal photocatalytic hydrogen production performance (2.10 mmol·g−1 L−1), which was 35 times higher than pristine CdS (0.06 mmol·g−1·L−1). We believe this strategy will endow new insights for the development of novel photocatalysts.

Photocorrosion of CdS nanorod arrays and fabrication of CdS@TiO2 core@shell nanorod arrays by atomic layer deposition for improved photostability

In this manuscript, an interesting phenomenon was found that partially or entirely hollow CdS nanotube arrays (PEH CdS NT) were obtained after photocorrosion of CdS nanorod arrays (NR). The forming process of PEH CdS NT was studied in detail. Afterwards, CdS@TiO2 core@shell NR with controllable TiO2 thickness onto CdS NR were preparated by atomic layer deposition (ALD), and the photostability of CdS@TiO2 core@shell NR was studied. Compared with unmodified CdS NR, the CdS@TiO2-1500 core@shell NR (the thickness of the TiO2 layer was 1500 ALD cycles) exhibited higher photostability within 300 s, which could be ascribed to the TiO2 nanolayer. TiO2 nanolayer can protect CdS NR from photocorrosion because it can effectually transfer the hole and the electron separation from photoluminescence (PL) characteristic. These results suggest that CdS@TiO2 core@shell NR fabricated by ALD are effective in protecting of CdS NR from photocorrosion.

Synthesis of CdS nanotubes and nanospheres by living bio-membrane bi-template

Semiconductor CdS nanotubes with a small ratio of length to diameter and nanospheres were simultaneously synthesized in the light of bio- mineralization process through living bio-membrane bi-template of mungbean sprouts at room temperature. The outside diameter of the nanotube is 220－ 240 nm and the inner diameter is 200－220 nm, the length is up to 600－700 nm and the ratio of length to diameter is 2:1. The nanoshpheres are 25 nm in diameter and well distributed. The XRD pattern indicates that these nanocrystals were crystallized in the cubic structure with lattice a = 5.818 Å. The optical properties of the products are illustrated, and their possible forming mechanism is explored.

Improved ion-diffusion assisted uniform growth of 1D CdS nanostructures for enhanced optical and energy storage properties

The defect-free growth of 1D CdS nanostructure faces serious setback since other techniques heavily bank on high-temperature growth, use of organic solvents, catalyst, seed layer, and expensive electrodes. Over and above, the organic ligand passivates the surface defect states that obstruct the optical pathway of 1D nanostructures; and make them unsuitable for device applications. Amidst all these shortcomings, low-cost ion-diffusion is one such technique which is simple, reproducible and eco-friendly for the synthesis of defect-free pure CdS nanotubes (NTs) through AAO membrane; reported here with strong merits, unlikely not possible with the conventional approaches. Aligned CdS NTs with tapered diameter at the bottom were fabricated for its possible incorporation into nanoscale photonic devices. The synthesized NTs showed strong photoluminescence (PL) near-band-edge emission and third order multiphonon LO mode in resonant Raman scattering (RRS); due to its small crystalline grain size. In addition, the well-aligned hollow CdS NTs on AAO membrane proved to be an excellent energy electrode material with a specific capacitance of 1207 F g−1 at a scan rate of 5 mV s−1 in 6 mol L−1 KOH with 10−4 mol L−1 of K3Fe(CN)6 as redox additive electrolyte.

TiO2–CdS supported CuNi nanoparticles as a highly efficient catalyst for hydrolysis of ammonia borane under visible-light irradiation

TiO2–CdS nanotubes (NTs) were used for the first time as a support to load metal nanoparticles (NPs) for the hydrolysis of ammonia borane (AB) which is a new strategy. The TiO2–CdS NTs support was first synthesized using a hydrothermal method, and then the CuNi NPs were loaded using a liquid-phase reduction method. The synthesized samples were characterized by XRD, SEM-EDS, TEM, XPS, ICP, UV–Vis, and PL analyses. The characterization results show that the CuNi NPs existed in the form of an alloy with a size of ~1.2 nm and uniformly dispersed on the support. Compared with their single metal counterparts, the bimetallic CuNi-supported catalysts showed a higher catalytic activity in the hydrolysis of AB under visible-light irradiation: Cu0·45Ni0·55/TiO2–CdS catalyst had the fastest hydrogen evolution rate with a high conversion frequency (TOF) of 25.9 molH2·molcat−1 min−1 at 25 °C and low activation energy of 32.8 kJ mol−1. Cu0.45Ni0.55/TiO2–CdS catalyst showed good recycle performance, maintaining 99.3% and 85.6% of the original hydrogen evolution rate even after five and ten recycles, respectively. Strong absorption of visible light, improved electron–hole separation efficiency, and metal synergy between Cu and Ni elements played a crucial role in improving the catalytic hydrolysis performance of AB. The catalyst prepared in this study provides a new strategy for the application of photocatalysts.

Computational Screening of Electrocatalytic Activity of Transition Metal-Doped CdS Nanotubes for Water Splitting

Exploring novel catalyst materials for water-splitting reaction is far-reaching in the current research scenario. CdS-derived nanostructures have been identified as potential catalysts for water sp...

Role of Dimensionality for Photocatalytic Water Splitting: CdS Nanotube versus Bulk Structure.

Using state-of-the-art density functional theoretical calculations, we have modelled a facetted CdS nanotube (NT) catalyst for photocatalytic water splitting. The overall photocatalytic activity of the CdS photocatalyst has been predicted based on the electronic structures, band edge alignment, and overpotential calculations. For comparisons, we have also investigated the water splitting process over bulk CdS. The band edge alignment along with the oxygen evolution reaction/hydrogen evolution reaction (OER/HER) mechanism studies help us find out the effective overpotential for the overall water splitting on these surfaces. Our study shows that the CdS NT has a highly stabilized valence band edge compared to that of bulk CdS owing to strong p-d mixing. The highly stabilized valence band edge is important for the hole-transfer process and reduces the risk of electron-hole recombination. CdS nanotube requires less overpotential for water oxidation reaction than the bulk CdS. Our findings suggest that the efficiency of the water oxidation/reduction process further improves in CdS as we reduce its dimensionality, that is going from bulk CdS to one-dimensional nanotube. Furthermore, the stabilized valence band edge of CdS nanotube also improves the photostability of CdS, which is a problem for bulk CdS.

Growth of CdS nanotubes and their strong optical microcavity effects.

Nanotubes are often formed by the folding of one-layer or multilayer compounds under microscopic catalytic growth conditions. Here, CdS nanotubes with tunable wall sizes and optical microcavities were prepared via a simple thermal evaporation co-deposition technique with Sn metal nanowire templating and ejection. Compared to core-shell Sn/CdS nanowires, which have poor microcavity quality, the hollow/CdS nanotubes have a higher quality factor (Q) that can reach approximately 400 in the spectral range of 550-800 nm when excited by a continuous-wave 405 nm laser. This high Q factor leads to low-threshold lasing and line-width narrowing due to the mode selection, which are important in many fields, including lasers, sensors, communications, and optical storage. A theoretical mode analysis of the hollow/CdS nanotubes with different thicknesses addressed their microcavity mode confinement and enhancements. This technique provides a new way to prepare semiconductor nanotubes for new photonic devices and photoelectric applications.

Titanate nanotubes coupled with Pt nanoparticles for the inhibition of CdS photocorrosion during visible-light-driven hydrogen production from formic acid

The photocatalytic performances of composites formed from Pt, CdS, and titanate nanotubes (TNTs) were examined for hydrogen production from an aqueous solution containing 10 vol% formic acid under visible light irradiation. Experimental results showed that CdS/TNTs exhibited much higher activity than CdS/TiO2, attributed to the specific properties of TNTs that promoted the separation of photogenerated charges. The valence states of the catalysts were determined from x-ray photoelectron spectroscopy (XPS) analysis. Results from photocatalysis experiments showed that TNT composites with Pt loading by the photo-deposition method had a significantly enhanced photoactivity and exhibited a hydrogen production rate of 661.1 μmol h−1, which is approximately 3.6 times higher than that observed for Pt deposited by the thermal impregnation method. This result indicates that smaller and more uniform Pt nanoparticles efficiently promoted the separation of photogenerated charges. Furthermore, XPS analyses results revealed that the TNT composites showed no significant amount of oxidized S0 or S6+ on the catalyst surface even after 3 h of reaction. Thus, we conclude that the photocorrosion of CdS was significantly inhibited when combined with TNTs during the photocatalytic reactions. The present work demonstrates the very high photocatalytic efficiency of TNT composites for the decomposition of HCOOH into hydrogen gas under visible light irradiation.

First-principles calculations of CdS-based nanolayers and nanotubes

The first-principles simulations using hybrid exchange-correlation density functional and localized atomic basis set were performed to investigate the properties of CdS nanolayers and nanotubes constructed from wurtzite and zinc blende phases. Different types of cylindrical and facetted nanotubes have been considered. The new classification of the facetted nanotubes is proposed. The stability of CdS nanotubes has been analyzed using formation and strain energies. Obtained results show that facetted tubes are favorable as compared to the most of cylindrical ones. Nevertheless, the cylindrical nanotubes generated from the layers with experimentally proved freestanding existence, also have a chance to be synthesized. Preliminary calculation of facetted nanotubes constructed from the zinc blende phase gives evidence for their possible using in the photocatalytic decomposition of water.

Facile preparation of ZnS/CdS core/shell nanotubes and their enhanced photocatalytic performance

In this paper, ZnS/CdS core/shell nanotubes were successfully synthesized by combining hydrothermal treatment and ion exchange conversion, and the significant influence of CdS content in the shell on photo absorption and photocatalytic activity was also investigated. The core/shell nanotubes structure of CdS deposition on both sides of ZnS nanotube was confirmed by scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). The room temperature PL spectra of ZnS/CdS core/shell nanotubes indicated that CdS on the shell can reduce the recombination of photon-generated electron and hole. The photocatalytic activity tests prove that ZnS/CdS nanotubes have much higher photocatalytic hydrogen production activity than ZnS nanotube and CdS nanotube. Under the irradiation of visible light, the highest photocatalytic hydrogen production rate of 110 μmol h−1 g−1 is observed over the ZnS/CdS core/shell nanotubes with CdS/ZnS molar ratio of 1:4, which is about 11.02 and 5.56 times more active than ZnS nanotube and CdS nanotube, respectively. The improved performance of ZnS/CdS samples can be due to the strong photo response in the visible light region and the efficient separation of electron–hole pairs.

Tunable structural and electrical properties of zigzag CdS nanotubes: A density functional study

AbstractWe report structural and electrical properties such as wall thickness, binding energy, curvature energy, band‐gap energy, work function etc. of various zigzag CdS nanotubes within the framework of density functional theory. Binding energy calculation reveals that all the nanotubes studied here are stable and they follow classical elasticity law. The wall thickness, band‐gap, and work function of the tubes are found to decrease with increasing tube diameter. Quantitatively, the band‐gap may be tuned from 1.711 to 2.162 eV and from 0.871 to 1.291 eV, respectively, while the work function may be varied from 6.081 to 6.239 eV and from 4.679 to 4.911 eV, respectively, by changing parameters such as diameter and atomic arrangement of the tubes. The results may be useful in designing various nanoscale devices.

Photocatalytic H2 production on trititanate nanotubes coupled with CdS and platinum nanoparticles under visible light: revisiting H2 production and material durability

The photocatalytic production of molecular hydrogen (H2) on ternary composites of Pt, CdS, and sodium trititanate nanotubes (NaxH2-xTi3O7, TNTs) is examined in an aqueous 2-propanol (IPA) solution (typically 5 vol%) at a circum-neutral pH under visible light (λ > 420 nm). The H2 production rates are dependent on the Pt-loading level, and the optimum production rate in the Pt/CdS/TNTs is approximately six times higher than that in Pt/CdS/TiO2. A D2O solution containing 5 vol% IPA leads only to the production of D2 molecules, whereas increasing the IPA amount to 30 vol% leads to the production of DH molecules. This indicates that the Pt/CdS/TNTs composites enable H2 production via true water splitting under our typical experimental conditions. X-ray photoelectron spectroscopy (XPS) analyses of the as-synthesized Pt/CdS/TNTs and those used for 6 and 12 h show that metallic Pt on the CdS/TNTs is less susceptible to oxidation than Pt on CdS/TiO2. In addition, photocorrosion of CdS (i.e., sulfate formation) is significantly inhibited during the photocatalytic H2 production reactions in the Pt/CdS/TNTs because of the efficient charge transfer via the TNTs framework. The Pt/CdS/TNTs samples are thermally more stable than Pt/CdS/TiO2 and CdS/TNTs, effectively inhibiting the formation of CdO during the thermal synthesis. Detailed surface characterizations of the as-synthesized ternary composites are performed using X-ray diffraction, transmission electron microscopy, energy dispersive spectroscopy, and XPS.

One-pot solvothermal synthesis and characterization of CdS nanotubes decorated with graphene for solar cell applications

Exfoliated graphene oxide was prepared and used to synthesize graphene-CdS (G-CdS) nanocomposites with different concentrations. CdS and G-CdS nanocomposites have successfully been synthesized via solvothermal method. The prepared materials were characterized by Fourier transform infrared, X-ray diffraction and high resolution transmission electron microscope techniques. CdS was found to grow as nanotubes with wurtzite crystal structure. CdS and G-CdS films were prepared by spin coating technique onto optical flat quartz and InP substrates. The optical properties were investigated by spectrophotometric measurements of the transmittance and reflectance over the spectral range 200–2500 nm. The optical band gap of the films was found to increase with increasing graphene content. The solar cells in the configuration of In/G-CdS/p-InP/Au:Zn with different graphene content were fabricated and compared with that fabricated with pristine CdS. The current-voltage characteristics of the devices were measured in dark and under illumination in which the basic diode parameters and photovoltaic parameters were estimated. The results demonstrate that the decoration of CdS with graphene is a promising simple approach to improve the electrical conversion efficiency of solar cells.

Aligned arrays of CdS nanotubes for high-performance fully nanostructured photodetector with higher photosensitivity

We report a novel and simple method to fabricate a high-sensitivity fully nanostructured photodetector by using CdS nanotubes (NTs) aligned arrays as active layer and Ag nanowires (NWs) transparent film as electrodes. The assembly of highly ordered and aligned CdS NTs arrays is obtained by a simple modified contact printing process. A fully nanostructured photodetector is fabricated by transferring the electrodes produced by Ag NWs network on the aligned CdS NTs arrays substrate, such that the aligned CdS NTs arrays as active layer are in contact with Ag NWs network as transparent electrodes. The resulting photodetector exhibits lower dark currents (<5 nA) and a higher photoresponse ratio (Ilight/Idark ≈ 219, 321) than that based on aligned arrays of CdS NWs, and its photosensitivity characteristics are even comparable to those of single nanostructure-based devices. In addition, the comparative studies of aligned NTs-based photodetetor in air and vacuum are investigated. The effects of the oxygen molecules on the photocurrent, dark current, rise time and decay time are investigated in details. This research may pave a way for large-scale fabrication of high performance and low cost nanostructured photodetectors for industrial applications.

An insight into the hybrid dye-sensitized solar cell from polyaniline-CdS nanotubes through impedance spectroscopy.

Composites of polyaniline (PANI) and cadmium sulfide nanoparticles (CdS NPs) are in situ synthesized by polymerizing aniline in acetic acid medium for different concentrations of CdS NPs. The composites, characterized by scanning and transmission electron microscopy, exhibit nanotubular morphology of PANI decorated with nanospheres of CdS NPs at their outer surface. The FTIR and UV-vis spectra indicate strong interaction between PANI and the CdS NPs suggesting a good conjugate for photovoltaic applications. The dc conductivities of the composite increase with an increase of the CdS concentration showing a maximum of 1.17 × 10-2 S cm-1 for the C200 sample (obtained by polymerizing 182 μL aniline with 200 mg CdS). The current-voltage plots indicate that the photocurrent is higher from the dark current and the separation between the dark current and photocurrent is maximum in C200. The effectiveness of these composites in DSSCs is studied under illumination of 100 mW cm-2 and the C200 device exhibits a maximum open circuit voltage of 0.73 V, a short circuit current of 8.22 mA cm-2, and a power conversion efficiency of 3.96%. The impedance study of the cells indicates that the lifetime of the photo-injected electrons is highest (1.34 ms) for the C200 sample, explaining the maximum PCE among the composites.

High-Performance Fully Nanostructured Photodetector with Single-Crystalline CdS Nanotubes as Active Layer and Very Long Ag Nanowires as Transparent Electrodes.

Long and single-crystalline CdS nanotubes (NTs) have been prepared via a physical evaporation process. A metal-semiconductor-metal full-nanostructured photodetector with CdS NTs as active layer and Ag nanowires (NWs) of low resistivity and high transmissivity as electrodes has been fabricated and characterized. The CdS NTs-based photodetectors exhibit high performance, such as lowest dark currents (0.19 nA) and high photoresponse ratio (Ilight/Idark ≈ 4016) (among CdS nanostructure network photodetectors and NTs netwok photodetectors reported so far) and very low operation voltages (0.5 V). The photoconduction mechanism, including the formation of a Schottky barrier at the interface of Ag NW and CdS NTs and the effect of oxygen adsorption process on the Schottky barrier has also been provided in detail based on the studies of CdS NTs photodetector in air and vacuum. Furthermore, CdS NTs photodetector exhibits an enhanced photosensitivity as compared with CdS NWs photodetector. The enhancement in performance is dependent on the larger surface area of NTs adsorbing more oxygen in air and the microcavity structure of NTs with higher light absorption efficiency and external quantum efficiency. It is believed that CdS NTs can potentially be useful in the designs of 1D CdS-based optoelectronic devices and solar cells.