Au CdS Research Articles

Fluorescence Enhancement of CdS:Ag Quantum Dots Co-Assembled with Au Nanoparticles in a Hollow Nanosphere Form.

Colloidal quantum dots (QDs) have exceptional fluorescence properties. Overcoming aggregation-induced quenching and enhancing the fluorescence of colloidal QDs have remained a challenging issue in this field. In this study, composite hollow nanospheres composed of Au nanoparticles (NPs) and CdS:Ag-doped QDs were successfully constructed through controlled microemulsion-based cooperative assembly. This method harnessed the localized surface plasmon resonance (LSPR) effect of Au NPs nearby doped QDs, resulting in enhanced doped QD fluorescence and the observation of the Purcell effect. The composite hollow nanospheres show a fluorescence enhancement compared to that of the pure CdS:Ag QDs. The enhanced fluorescence was demonstrated to come from the synergetic enhancement of the absorption and emission transition of the doped QDs. This approach provides a feasible technological pathway to address the challenge of improving the fluorescence performance of the doped QDs.

Localization-of-light-induced stimulated Mie scattering: Laser pulse duration adjustment in a broad range

Backward stimulated Mie scattering (BSMS) holds significant potential across various fields due to its superior properties. In this study, we demonstrate that metal-semiconductor hybrids of CdS shell and Au core markedly enhanced the BSMS compared with pure CdS nanoparticles. Theoretical analysis suggests that the enhancement should be attributed to multi-photon excitation and increased Anderson localization of light. The localized light interacts with the incident light, creating conditions conducive to BSMS, thereby improving efficiency and reducing the threshold. The enhanced localization of light is a result of the increased nonlinear refractive index induced by electron-sink effect. Importantly, we propose a novel strategy, on the basis of BSMS, to adjust the pulse duration of laser output in a broad range without any frequency shift.

A comparative DFT study on the adsorption properties of lithium batteries thermal runaway gases CO, CO2, CH4 and C2H4 on pristine and Au doped CdS monolayer

The thermal runaway gases, such as CO, CO2, CH4, and C2H4, will leak from the battery electrolyte when lithium batteries in extreme discharge or thermal runaway conditions. The structural properties, differential charge density (DCD), density of state (DOS), gas adsorption properties, desorption time, work function and front-orbit theory calculation of pristine and Au doped CdS monolayer are explored and compared by first-principle calculation. The adsorption energy of CO, CO2, CH4 and C2H4 on the surface of Au–CdS are –0.89 eV, –0.40 eV, –0.14 eV and –0.77 eV, respectively. After doping, the adsorption type of CO and C2H4 are chemical type. Partial density of states shows that the gas molecules react with doped precious metal atoms. The adsorption ability of Au–CdS can be ranged as CO>C2H4>CO2>CH4. C2H4 on the surface of Au–CdS can desorb within 10 s at room temperature. As a result, Au–CdS exhibits tremendous prospective application as CO or C2H4 gas sensor. This study demonstrates that the adsorption and sensing properties of CdS monolayer can be improved effectively by the introduction of precious metal.

Plasmon-Induced and Multichannel Electron Transfer-Improved Photocatalytic Hydrogen Production by CdS–Au–Pt Heterostructure

Plasmon-Induced and Multichannel Electron Transfer-Improved Photocatalytic Hydrogen Production by CdS–Au–Pt Heterostructure

Synthesis and highly efficient photocatalysis applications of CdS QDs and Au NPs Co-modified KTaO3 perovskite cubes.

Perovskite structure has attracted interest for the past few years due to its prospects in photocatalysis. The exploration of efficient perovskite photocatalysts still receives much attention in the field of chemistry and materials science. Herein, KTaO3 cubes are first prepared by hydrothermal synthesis, then Au nanoparticles (NPs) are loaded on the cubes by photodeposition, and finally, CdS quantum dots (QDs) are modified on Au/KTaO3 cubes using an in situ growth method, and eventually tantalum-based photocatalysts in a ternary system are successfully prepared. The fabricated CdS/Au/KTaO3 reveals photocatalytic properties in hydrogen evolution and degradation of dyes. In particular, under the same conditions, the photocatalytic hydrogen evolution rate of the optimized 13%CdS/1.3%Au/KTaO3 (13% and 1.3% are the contents of CdS and Au in the composite photocatalyst, respectively) is 2.892 mmol g-1 h-1. Compared to those of bare KTaO3 and CdS, it is approximately 107-fold and 8.5-fold enhanced, respectively. And the sizes of CdS and Au in the photocatalyst are 4.21 and 15.07 nm. The increased photoactivity of the composite can be ascribed to the synergistic effect of several factors, such as: the Au NPs' surface plasma resonance (SPR) impact improves the production of hot electrons and the ability of KTaO3 to capture light; effective integration between CdS QDs and KTaO3 cubes forms a heterojunction and expands the absorption range of KTaO3 in the visible light spectrum, improving the utilization rate of visible light effectively. Hence, a co-modification strategy has been proposed for endowing KTaO3 perovskites with new structures and different functions, and it is expected to become a general strategy to find an illuminating strategy for achieving improvements and enhancements in the photocatalytic field.

Ultrathin Niobate Nanosheet Assembly with Au NPs and CdS QDs as a Highly Efficient Photocatalyst.

Niobate nanosheets have aroused widespread interest in recent years for their prospects in catalysis. The exploration of 2D niobate catalysis with stable and efficient properties is still the focus in chemistry and materials science. Herein, the successful fabrication of 2D CdS/Au/HNb3 O8 catalyst is demonstrated which revealed efficient photocatalytic properties in H2 evolution, oxidative self-coupling of amines to imines, and degradation of dyes. Especially the assembled architecture can give a rate of 5.85 mmol ⋅ g-1 ⋅ h-1 of photocatalytic H2 evolution, an ∼254-fold enhancement, compared with bare HNb3 O8 nanosheets under identical conditions. In accordance with density functional theory (DFT) and X-ray adsorption fine structure (XAFS) analyses, the vast improvements are benefited from efficient migration and separation of charge carriers. Besides, the surface plasma resonance (SPR) effect of Au NPs enhances the light harvesting capacity and boosts the generation of hot electrons, efficiently improving the visible-light absorption.

Strategy modulation of energy transfer for the plasmon-promoted hydrogen evolution in ternary CdS–Au–MoS2

Nano noble metals with surface plasmon resonance effect have been widely applicated in photocatalytic hydrogen production, however, the poor oxidation/reduction efficiency is the major obstruction for the extensive application of the water splitting. In this study, the ternary nanocomposite, CdS–Au–MoS2, is structured for the strategic modulation of the energy transfer of the incident light. Comparing with pristine CdS nanowires, an obvious improvement with the maximum H2 evolution rate of 11.43 mmol·g−1·h−1 was obtained after the conjunction of Au nanorods, and the photocatalytic activity was further promoted about ∼2.04 times through the surface modification of the MoS2 quantum dots. A positive synergistic effect of the plasmon and co-catalyst was proposed, where the Au nanorods acted as the source of hot electrons while the MoS2 quantum dots served as the active sites for hydrogen evolution reaction. Compared with similar nanostructures reported previously, the present superior photoactivity response is ascribed to the plasmon-promoted effect combined with the co-catalyst, which corresponds to the electric field distribution of the finite-difference-time-domain simulation. These intriguing results expanded the comprehensive understanding of plasmon-assisted photochemistry and provided a promising strategy for the rational design of novel plasmonic photocatalysts.

Plasmon resonance-induced photoluminescence enhancement of CdS quantum dots thin films on fabricated Au/Ag/Cu metallic thin films

Multi-metallic nanoparticles (NPs) offer tunable Localized Surface Plasmon Resonance properties which depend on their elemental and configurational variations, which have been used in optical sensing and biomedical imaging. In the present study, the composition and optical properties of hybrid nano-structured thin films of CdS quantum dots (QDs) incorporated on Au-, Ag- and Cu-NPs for photonic applications are investigated. Initially, CdS QDs were prepared by chemical reduction method and characterized by Transmission electron microscopy, UV–Visible absorption spectroscopy and Fourier transform infrared spectroscopy techniques. Then nanometer thin films of Au, Ag and Cu were fabricated by thermal evaporator and insitu heating along with uniform rotation of substrate was used to convert these into respective uniform spherical NPs on ITO substrate. Further, CdS QDs were deposited over these metallic NPs and we observed enhanced photoluminescence (PL) of CdS QDs due to Surface Plasmon Resonance effect by these metallic NPs. The time resolved spectroscopy of these films was carried out to correlate the enhanced PL emission from CdS–Au–Ag–Cu-ITO thin film. The results of the present study of these plasmonic nanostructures will be further utilized in metal enhanced fluorescence sensors.

Voltage-Switchable Biosensor with Gold Nanoparticles on TiO2 Nanotubes Decorated with CdS Quantum Dots for the Detection of Cholesterol and H2O2.

A thin layer of gold nanoparticles (Au NPs) sputtered on cadmium sulfide quantum dots (CdS QDs) decorated anodic titanium dioxide nanotubes (TNTs) (Au/CdS QDs/TNTs) was fabricated and explored for the nonenzymatic detection of cholesterol and hydrogen peroxide (H2O2). Morphological studies of the sensor revealed the formation of uniform nanotubes decorated with a homogeneously dispersed CdS QDs and Au NPs layer. The electrochemical measurements showed an enhanced electrocatalytic performance with a fast electron transfer (∼2 s) between the redox centers of each analyte and electrode surface. The hybrid nanostructure (Au/CdS QDs/TNTs) electrode exhibited about a 6-fold increase in sensitivity for both cholesterol (10,790 μA mM-1 cm-2) and H2O2 (78,833 μA mM-1 cm-2) in analyses compared to the pristine samples. The hybrid electrode utilized different operational potentials for both analytes, which may lead to a voltage-switchable dual-analyte biosensor with a higher selectivity. The biosensor also demonstrated a good reproducibility, thermal stability, and increased shelf life. In addition, the clinical significance of the biosensor was tested for cholesterol and H2O2 in real blood samples, which showed maximum relative standard deviations of 1.8 and 2.3%, respectively. These results indicate that a Au/CdS QDs/TNTs-based hybrid nanostructure is a promising choice for an enzyme-free biosensor due to its suitable band gap alignment and higher electrocatalytic activities.

Evaluation for pharmacokinetic exposure of cytotoxic anticancer drugs in elderly patients receiving (R-)CHOP therapy

(R-)miniCHOP therapy, which delivers approximately half-doses of the (R-)CHOP regimen, has shown efficacy and safety in patients who are more than 80 years old. This study aimed to compare the area under the plasma concentration–time curves (AUCs) of vincristine (VCR), doxorubicin (DXR), and cyclophosphamide (CPA) between (R-)CHOP and (R-)miniCHOP regimens. The AUCs were compared between patients aged 65–79 years receiving (R-)CHOP therapy and those aged 80 years and older receiving (R-)miniCHOP therapy. Age was not an independent variable for predicting the dose-adjusted AUCs (AUC/Ds) of cytotoxic anticancer drugs. The median AUCs of DXR and CPA were significantly smaller in the (R-)miniCHOP group than in the (R-)CHOP group (168.7 vs. 257.9 ng h/mL, P = 0.003, and 219.9 vs. 301.7 µg h/mL, P = 0.020, respectively). The median AUCs of VCR showed the same trend but the difference was not significant (24.83 vs. 34.85 ng h/mL, P = 0.135). It is possible that the AUCs of VCR, DXR, and CPA in patients aged 80 years and older receiving (R-)miniCHOP therapy may be lower than those in patients 65–79 years old receiving (R-)CHOP therapy.

Synthesis of the hybrid CdS/Au flower-like nanomaterials and their SERS application

The CdS flower-like nanomaterials (FLNMs) were synthesized by a facile hydrothermal method. With the help of the hydrophilic group on polyvinyl pyrrolidone molecules, the CdS FLNMs were decorated with Au nanoparticles (NPs) through in situ chemical reduction of HAuCl4. The hybrid CdS/Au FLNMs were investigated through surface-enhanced Raman scattering (SERS). It is found that they can detect crystal violet, Rhodamine B and malachite green as low as 1.0 × 10−8 M, 1.0 × 10−8 M, and 1.0 × 10-7 M respectively. In addition, the theoretical simulation was carried out by the discrete dipole approximation (DDA) method. It is found that the strong electric field of Au dimer and the coupling electric field between Au NPs and CdS FLNMs makes a significant improvement in SERS. Therefore, the hybrid CdS/Au FLNMs have a potential in applications such as detecting organics.

CdS quantum dots/Au nanoparticles/ZnO nanowire array for self-powered photoelectrochemical detection of Escherichia coli O157:H7

In this paper, the hydrothermally grown ZnO nanowire array (NWs) was modified by Au nanoparticles (NPs) and CdS quantum dots (QDs) to construct a high-performance photoelectrochemical (PEC) electrode. The aligned ZnO NWs, which decorated Au NPs and CdS QDs have the effective light absorption range from UV to visible region. This hybrid structure provided a self-powered PEC electrode with a favorable energy-band configuration for fast charge separation and transportation. Meanwhile, the Au NPs and CdS QDs also made increase of the surface area to improve the immobilization of the analytes. After assembling aptamer as recognition element, this composite nanoarray was further developed as a self-powered PEC biosensor by synergizing above multiple enhancement factors. The PEC aptasensor exhibited a rapid response in a wide linear range of 10–107 CFU/mL with the detection limit as low as 1.125 CFU/mL to Escherichia coli O157:H7 (E. coli O157:H7). This approach would offer an alternative PEC transduction for fast environment monitoring and clinical diagnosis related to pathogenic bacteria.

Pressure-Induced Transformations of Three-Component Heterostructural Nanocrystals with CdS–Au2S Janus Nanoparticles as Hosts and Small Au Nanoparticles as Satellites

Heterostructural nanocrystals (HNCs) have drawn enormous attention because of the combined and synergistic properties inherited from their individual components and interactions. Here we design a t...

Multi-functional electrochemiluminescence aptasensor based on resonance energy transfer between Au nanoparticles and lanthanum ion-doped cadmium sulfide quantum dots

Novel lanthanum ion-doped cadmium sulfide quantum dots (CdS:La QDs) were synthesized and characterized by transmission electron microscopy (TEM) and photoluminescence (PL). Based on CdS:La QDs as the electrochemiluminescence (ECL) luminophores, a distance-dependent ECL intensity enhanced or quenched system between CdS:La QDs and gold nanoparticles (Au NPs) was designed. Firstly, ssDNA 1 was linked to the CdS:La QDs modified glassy carbon electrode via amide bond. Then the prepared Au NP–ssDNA 2 conjugates were used to hybridize with ssDNA 1, the surface plasmon resonances (SPR) of Au NPs enhanced ECL intensity (signal on) while Au NPs and CdS:La QDs were separated at a certain distance. Secondly, In the presence of Hg2+, the oligonucleotide conformation changed from linear chain to hairpin due to the thymine–Hg2+–thymine (T–Hg2+–T) base pairs. ECL quenching (signal off) achieved lie in resonance energy transfer (RET) between the CdS:La QDs and the proximal Au NPs at a close distance. Finally, after being incubated with TB, a strong and stable TB–aptamer complex was generated, which led to the release of Au NP–ssDNA 2 conjugates. The ECL signal of the CdS:La QDs was ultimately recovered (signal on again). The “on–off–on” approach was used to detect Hg2+ and TB, sensitively and respectively. The line ranges were 1.00 × 10−12 –1.00 × 10−5 mol L−1 and 1.00 × 10−16 –1.00 × 10−6 mol L−1, respectively. The low limits of detection (S/N = 3) were at 3.00 × 10−13 mol L−1 and 3.00 × 10−17 mol L−1. Moreover, the ECL sensor exhibited high selectivity and good stability, and was successfully applied to the detection of TB in real sample.

A ratiometric fluorescent probe for detection of uric acid based on the gold nanoclusters-quantum dots nanohybrid.

Herein, we developed a simple strategy for the preparation of dual-emission fluorescent nanohybrid constructed of gold nanoclusters (Au NCs) and quantum dots (QDs). The bovine serum albumin-capped Au NCs can be directly used as the stabilizers to prepare CdS QDs. The synthesized bovine serum albumin-capped Au NCs and CdS QDs nanohybrid (BSA-Au NCs/QDs) displayed dual emission bands respectively at 490 nm and 685 nm. An obvious fluorescence quenching around 685 nm was detected with the addition of hydrogen peroxide (H2O2) in the presence of Fe2+ ions, and the fluorescence emission peak at 490 nm was not affected. Uricase can break down uric acid to produce H2O2, and we further used the BSA-Au NCs/QDs as a ratiometric fluorescent probe for determination of uric acid with the linear range from 0.67 to 60 μmol·L-1 and the detection limit of 0.21 μmol·L-1.

Yolk-shell nanostructures as an emerging photocatalyst paradigm for solar hydrogen generation

With porous shells and mobile cores, yolk-shell nanostructures provide great structural advantage for mass transport-related applications such as photocatalysis. In this work, Au–Cu7S4 yolk-shell nanostructures are synthesized from Au–Cu2O core-shell templates. The Cu7S4 shell is then converted to CdS through a cation exchange process to produce Au–CdS yolk-shell photocatalysts for hydrogen generation. Ultrafast transient absorption and finite-difference time-domain simulation are used to investigate electronic interaction between Au nanoparticle core and the surrounding CdS shell. Additionally, a new method is presented to simulate chemical transport and quantitatively compare diffusion kinetics by monitoring mass transport through the porous CdS shell with dye molecules as optical probes. The highest hydrogen generation rate of 3390 μmol g−1 h−1, corresponding to an adequate apparent quantum yield of 4.22% at 420 nm, is achieved for Au–CdS with the largest void size. The enhancement in photocatalytic performance with increase in void size is mostly attributed to improved mass transport kinetics, with additional gains from more efficient charge transfer and stronger surface plasmon resonance-mediated near-field effects. This comprehensive study demonstrates that void size is a critical structural parameter in optimizing the performance of yolk-shell nanostructures for photocatalysis or other mass-transport related applications.

Z-scheme structure SnS2–Au–CdS with excellent photocatalytic performance for simultaneous removal of Cr(VI) and methyl orange

A highly efficient Z-scheme photocatalyst SnS2–Au–CdS was fabricated by photoreduction and thiourea medium deposition methods. It was found that Au nanoparticles were successfully anchored on the surface of SnS2, and CdS nanoparticles were further deposited on the surface Au nanoparticles by the strong interaction of S–Au. Compared to SnS2, CdS, SnS2–Au, and SnS2–CdS, Z-scheme structure SnS2–Au–CdS shows the best photocatalytic performance for methyl orange (MO) degradation and Cr(VI) reduction under visible light irradiation. The outstanding photocatalytic performance of SnS2–Au–CdS can be ascribed to the special Z-scheme structure which not only improves the separation of photogenerated charge carriers but also preserves its high redox ability. In addition, SnS2–Au–CdS exhibited synergistic effects in photocatalytic removal of Cr(VI) and MO.

Enhanced photoelectrochemical performance with plasmon-induced hot electron injection of gold nanoparticle

Due to the capacity of efficiently harvesting and converting light energy, the property of localized surface plasmon resonance (LSPR) in the noble metal is employed as an efficient assistant in photoelectrochemical water splitting. In this study, the Au nanoparticles (NPs) were modified on the 1D ordered structure as the active sites of the SPR effect for the plasmon-enhanced photocatalytic performance. A maximum current density of 4.45 mA cm−2 at 1.2 V (versus RHE) was obtained in alkaline solution without a sacrificial agent for the ZnO–CdS–Au photoelectrode, which was 1.48 times higher than that of the ZnO–CdS nanorods without Au decoration, as well as the ~235% enhancement of the photoconversion efficiency. Compared to similar nanostructures previously reported, the present superior photoactivity response was ascribed to the injection process of the energetic hot electrons generated through the excitation and decay of surface plasmons in the Au NPs, resulting in the efficient separation and migration of photogenerated electron–hole pairs in ternary nanorod arrays. These excellent results have expanded the comprehensive understanding of hot electron migration in plasmonic NP-semiconductor nanocomposite, and provided a promising strategy for the rational design of the plasmonic-enhanced photocatalyst.

Efficient photoredox conversion of alcohol to aldehyde and H2 by heterointerface engineering of bimetal-semiconductor hybrids.

Controllable and precise design of bimetal- or multimetal-semiconductor nanostructures with efficient light absorption, charge separation and utilization is strongly desired for photoredox catalysis applications in solar energy conversion. Taking advantage of Au nanorods, Pt nanoparticles, and CdS as the plasmonic metal, nonplasmonic co-catalyst and semiconductor respectively, we report a steerable approach to engineer the heterointerface of bimetal-semiconductor hybrids. We show that the ingredient composition and spatial distribution between the bimetal and semiconductor significantly influence the redox catalytic activity. CdS deposited anisotropic Pt-tipped Au nanorods, which feature improved light absorption, structure-enhanced electric field distribution and spatially regulated multichannel charge transfer, show distinctly higher photoactivity than blank CdS and other metal-CdS hybrids for simultaneous H2 and value-added aldehyde production from one redox cycle.

Synthesis of magnetically separable Fe3O4–Au–CdS kinked heterotrimers incorporating plasmonic and semiconducting functionalities

In a straightforward two-step synthesis process, Au–Fe3O4 dimer was injected as a seed into the Cd precursor solution yielding a hybrid heterotrimer of Fe3O4–Au–CdS, integrating magnetic, plasmonic and semiconducting functionalities in one-particle.