Au Doping Research Articles

Au modified PrFeO3 with hollow tubular structure can be efficient sensing material for H2S detection.

The H2S concentration in exhaled breath increases marginally with the progress of periodontal disease, and H2S is considered to be one of the most important gases related to meat and seafood decomposition; however, the concentration of H2S is low and difficult to detect in such scenarios. In this study, Au–PrFeO3 nanocrystalline powders with high specific surface areas and porosities were prepared using an electrospinning method. Our experimental results show that loading Au on the material provides an effective way to increase its gas sensitivity. Au doping can decrease the material’s resistance by adjusting its energy band, allowing more oxygen ions to be adsorbed onto the material’s surface due to a spillover effect. Compared with pure PrFeO3, the response of 3 wt% Au–PrFeO3 is improved by more than 10 times, and the response time is more than 10 s shorter. In addition, the concentration of H2S due to the decomposition of shrimp was detected using the designed gas sensor, where the error was less than 15%, compared with that obtained using a GC-MS method. This study fully demonstrates the potential of Au–PrFeO3 for H2S concentration detection.

First Principle Calculation: Effect of Doped Gold Clusters with Platinum Atom on Chemical Catalysis

In this paper, we present a systematic computational study based on the density function theory (DFT), Which aims to shed light on the potential effects of doped gold Au clusters with a platinum Pt atom,and finding the new structural and electronic properties that will be enjoyed by gold doped with platinum PtAun (n = 1-9) clusters, So that the most stable clusters are selected from the rest of the isomers for each cluster size. We doped Aun clusters with Pt atom, we obtained very interesting results, Stable and most stable structures reveal three-dimensional structures starting from (n=6), Also, the results of the fragmentation energy and the second difference in binding energy of these clusters in relation to their size have been studied in depth. The electronic properties, such as the Homo-Lumo gap energy, Vertical ionization potential (VIP) and adiabatic ionization potential (AIP) as a function of cluster size are also studied and discussed. All properties calculated by the generalized gradient approximation (GGA) were compared with the results of the local density approximation (LDA). Whereas, the results showed that the Aun clusters doped with Pt atom changed significantly.

Ion implanted substitutionally dispersed Au in TiO2 nanostructures for efficient and stable dye sensitized solar cells

Various optical and electrical properties of noble metal doped TiO2 nanomaterials are found to vary remarkably with change in concentration and nature of doping. In the present work, ion implantation technique has been employed for generating substitutional and interstitial Au doping in TiO2 nanoparticle-nanofiber (NP–NF) composites. Experimentally, the presence of Au at substitutional and interstitial sites of TiO2 was detected through X-ray photoelectron spectroscopy. Depth profiling of implanted Au ions confirmed the presence of Au upto 70 nm. From the theoretical simulations, it was realized that substitutional Au doping results in higher strain and lower band gap contrary to pristine TiO2 and interstitial Au doped TiO2. Finally, the Dye sensitized solar cell (DSSC) prepared with substitutional doping was found to be 23.9% more efficient than interstitial Au based DSSC owing to enhanced light harvesting, higher fermi level and minimal recombinations as corroborated from current density-voltage and electrochemical impedance spectroscopy studies.

Random lasing from gold-doped zinc oxide nanorods

In this article, we report our investigation of random laser emission from Au-doped ZnO nanorods fabricated by chemical bath deposition (CBD) at different Au concentrations. The crystal structure, morphological variations, and optical properties of the nanorods were investigated. The crystallite size of the doped nanorods increased with Au concentration, indicating lattice expansion of ZnO after Au doping. Photoluminescence (PL) measurements revealed a broad emission centered at 570 nm which is attributable to the transitions associated with excess oxygen vacancies due to doping. The lowest threshold for lasing was observed at 32 mJ/cm2 of pump power with the spectral width of the lasing peak ∼0.18 nm from the sample with the highest Au atomic doping percentage (∼1.2 at.%). This study reveals a possible solution to lowering random lasing threshold by doping the gain material.

Design of Au Surface‐doped PtFe Catalyst to Modulate Oxygen Binding Energy for Highly Efficient Oxygen Reduction Reaction

AbstractAs ideal cathode catalysts for proton exchange membrane fuel cells (PEMFCs), the oxygen reduction reaction (ORR) activity and durability of Pt‐based alloys can be improved further. This study presents the catalyst with Au doping on the surface of an ordered PtFe alloy (Au‐PtFe/C) utilizing a synergistic process of microwave reduction and chemical replacement, as well as the reorganization of a Pt‐rich surface using acid etching and high temperature annealing. Physical characterization indicated that the oxygen binding energy on the surface of Au‐PtFe/C was more effective at promoting the ORR reaction than commercial Pt/C, which contributes significantly to its enhanced activity. Further electrochemical tests revealed that the Au‐PtFe/C catalyst exposes abundant active sites for ORR, with mass and specific activity up to 12 and 8 times that of commercial Pt/C, respectively. Additionally, the catalyst demonstrated remarkable durability following 10,000 cycles of accelerated durability tests (ADT) in acidic circumstances. In PEMFC test, the single cell with an Au‐PtFe/C cathode also performed admirably when compared with commercial Pt/C. Owing to its facile synthesis, low cost, and exceptional performance, this bimetal‐doped ordered Pt‐based alloy has the capability to be a promising component in fuel cells commercialization.

Theoretical study of structure sensitivity on Au doped CeO2 surfaces for formaldehyde oxidation: The effect of crystal planes and Au doping

Engineering the surface structure of ceria-based catalysts at the atomic scale is a powerful strategy for boosting catalytic performance. Here, we carried out density functional theory calculations to investigate structure–activity relationships of Au-CeO2 catalysts with (1 1 1), (1 1 0), and (1 0 0) surfaces exposed in common CeO2 nanopolyhedra, nanorods and nanocubes, respectively. On stoichiometric AuCe1-xO2(1 1 1), (1 1 0) and (1 0 0) catalyst surfaces, HCHO oxidation follows the Mars van Krevelen mechanism. Calculations show that the migration of Au atoms on the surface of AuCe1-xO2(1 1 0) leads to a more stable configuration and improved HCHO oxidation performance than the undistorted (1 1 0) surface. On defective AuCe1-xO2(1 1 0) and (1 0 0) surfaces, HCHO oxidation follows the co-action of the Langmuir-Hinshelwood and Mars van Krevelen mechanisms with HCHO and O2 co-participation and surface reduction by the removal of lattice oxygen. Adsorbed O2 species contribute to a decrease in the energy barriers of the reaction steps. With the easy reducibility and lower energy barriers, the defect surfaces are more conducive to HCHO oxidation than stoichiometric surfaces. Whether stoichiometric surfaces or defective surfaces, (1 1 0) is most active for HCHO oxidation with the lowest activation energy for the rate-determining step, followed by (1 1 1), and then (1 0 0). Microkinetic simulations offer additional support for this result. Dopant Au atoms activate surface oxygen, and decrease the formation energy of oxygen vacancies. Au also reduces the energy barriers of key reaction steps on AuCe1-xO2(1 1 1) (1 1 0) (1 0 0) surfaces as compared to the pristine ceria surfaces. These calculations provide insight into the interaction between Au and CeO2 with different surface terminations and the effect of the CeO2 crystal plane and their reactivity for HCHO catalytic oxidation.

Metal doped black phosphorene for gas sensing and catalysis: A first-principles perspective

Transition metal doped black phosphorene is widely studied for gas sensing and catalysis applications. In this work, we find that for Au, Ag and Pt dopants, the black phosphorene with two P atoms being substituted by one metal atom is more stable than the one with only one P atom being substituted. Among them, Au-2P and Ag-2P can be used for NO gas detection and sensing under strain between −6% and 6%. Au-, Ag- and Pt-2P all show better catalytic performance toward hydrogen evolution reaction than pristine black phosphorene. However, only Au-2P and Ag-2P can maintain the excellent catalytic activity under extra strain in the range of −6% to 6%. This work is not only an important supplement to the basic research of doped black phosphorene, but also important for guiding preparation and practical applications of doped black phosphorene in the future.

Heteroatom doping and supramolecular assembly promoted copper nanoclusters to be a stable & high fluorescence sensor for trace amounts of ATP determination

The glutathione-capped bimetallic copper and gold nanoclusters (CuAuNCs@GSH) were achieved through Au doping into the unstable copper nanoclusters (CuNCs@GSH), which induced the photoluminescence stabilization time increase from 4 to 7 days. Moreover, the Ce3+ introduction further significantly increased the stable storage time (from 7 to 25 days) and the emission intensity (near 140-fold), accompanying a quantum yields enhancement from 0.30% to 22%. Transmission electron microscopy (TEM) revealed the Ce3+-induced larger assemblies of CuAuNCs-Ce3+ from monodispersive CuAuNCs@GSH nanodots. The fluorescence enhancement was attributed to the aggregation-induced emission (AIE) property of CuAuNCs@GSH, where Ce3+ was bound to the ligands GSH and reduced the non-radiative relation of the excited states. Besides, the strong interaction between ATP and Ce3+ dissociated the CuAuNCs-Ce3+ assembly into monodisperse nanoclusters and recovered the weak luminescence. Therefore, the CuAuNCs-Ce3+ assembly was applied to determine ATP, which exhibited high selectivity and sensitivity with a detection limit of 53 nM. Finally, the method was successfully applied to determine ATP in diluted serum with very high recovery. Therefore, the present study provides an efficient way to improve the fluorescence properties of metal nanoclusters and supplies a selective and sensitive ATP sensor.

Beneficial effect of Au and Pt doping of the Ag-(100) surface for thiophene and pyridine adsorption from density functional theory calculations

We use density functional theory including van der Waals (vdW) interactions to investigate the adsorption of thiophene (C 4 H 4 S) and pyridine (C 5 H 5 N) on the Ag-(100) surface doped by Pt, Au, Pt 2 , Au 2 , PtAu, Pt 4 and Au 4 atoms. Our calculated adsorption energies show that the dopant atoms enhance significantly the binding of the C 4 H 4 S and C 5 H 5 N molecules. More precisely, the thiophene and the pyridine molecules present a larger interaction with the surface when it is doped with Pt atoms, indicating that Pt atoms have an extremely strong adsorption capacity for both molecules. In addition, the adsorption height of the different configurations shows that the Pt dopant atoms enhance the S-Pt and N-Pt bonds strength, while the C S and C N bond distances are elongated in the presence of Pt atoms. The effect of Au atoms is similar to the ones of Pt, albeit the adsorption is weaker. The Bader analysis reveals that charge transfer almost occurs from the thiophene and pyridine molecules to the studied surfaces, with a modest increase in charge transfer in certain cases, while, the charge density difference (CDD) results supported the adsorption behaviour of both molecules. Overall, it is expected that doping the Ag-(100) surface with either Pt or Au atoms will have a significant effect on the reactivity of thiophene and pyridine.

Hybridizing strategy of decatungstate by Au nanoparticles for enhanced photo-catalytic oxidation of hydrocarbons by dioxygens

Decatungstate (DT) is very potential photo-catalyst for the dioxygens (O2)-based selective oxidation but still needs to be improved in photo-catalytic efficiency and regeneration. This paper discloses that Au nanoparticles (NPs)-loaded DT (Au/DT) is conveniently synthesized via the reduction of chloroauric acids introduced in the synthesis of DT. A series of characterizations and quenching tests support that the doped Au NPs can remarkably improve the visible-light- harvesting and photo-excited quantum efficiencies of DT, and as the excellent electronic transport carriers, they also plays an additional role in converting O2 into the active superoxide (•O2-) anion radical. As a result, the suggested Au/DT exhibits a significantly enhanced photo-catalytic efficiency for the visible-light-triggered selective oxidation of inert hydrocarbons under 25–28 °C and 1 atm pure O2 atmosphere. Under optimized conditions, the best 1%Au/DT achieves 64.2% conversion and 93% acetophenone selectivity in the photo-oxidation of ethylbenzene and it has an outstanding regeneration ability.

Fabrication of Au:ZnO thin films by a solution-assisted route for application in photo-electrocatalytic degradation of methylene blue (MB)

The influence of Au doping in ZnO thin films was studied with respect to photoelectrocatalytic degradation of methylene blue (MB). Influence of Au doping concentration onto PEC structural morphological, optical and luminescence properties of the ZnO thin films were thoroughly investigated. The maximum value of Isc and Voc for 3 at. % Au:ZnO thin films confirms the optimization of doping percentage. XRD and SEM were used to study the structure and morphology of the films. Films were nanocrystalline and exhibit a hexagonal crystal structure with no additional phases of gold compounds. For degradation of MB, Au:ZnO films were used as photoelectrode, it was observed that due to Au:ZnO 80% degradation of MB occurs in 150 min. Moreover, large area (100 cm2) Au doped ZnO thin films have been prepared on FTO coated glasses (10–15 Ω). Photocorrosion of ZnO electrode was examined by atomic absorption spectroscopy and no zinc was observed in AAS measurement. Copyright © 2017 VBRI Press.

Influence the performances of hopcalite catalysts by the addition of gold nanoparticle for low temperature CO oxidation

The catalytic conversion of carbon monoxide (CO) into carbon dioxide (CO 2 ) at a low temperature is very important procedure for all living beings present in the environment. The present study represents that the addition of gold (Au) nano-particles, by the deposition-precipitation method into the hopcalite (CuMnOx) catalyst has been improving their performances for CO oxidation. The CuMnOx catalyst loading by 0.75 wt% Au was representing that the best catalytic activity for CO oxidation than the other catalysts loading by 0.25, 0.5 and 1 wt% Au. The small amount of Au doping (0.75 wt%) in CuMnOx catalyst improves their performances for CO oxidation at an ambient conditions. The gold nano-particles will be introducing the new active sites into the CuMnOx catalyst surfaces and decreases the deactivation of catalyst. The lattice oxygen movement was a major important factor which can influences the performances of hopcalite catalyst for CO oxidation. The calcinations strategies (reactive calcinations and traditional calcinations) of the precursor have huge impacts on the performances of resulting catalysts. The reusability of Au promoted CuMnOx catalyst was also measured and found that this catalyst does not have any major changes in its catalytic performances still after the reuses.

An insight of physical and antibacterial properties of Au-doped ZnO dip coated thin films

Undoped and Au-doped ZnO thin films were dip coated on crown glass substrates by sol-gel process technique. The role of Au (1–5 at. wt.%) on structural, magnetic, morphological, dielectric, antibacterial and optical properties of the ZnO films were studied. XRD results depict that all films have a hexagonal wurtzite structure of ZnO and are a-axis oriented. The crystallite size thin films are decreased with an increase in Au doping percentage. Optical properties also confirmed that the s crystallinity degraded with the increase in Au percentage. UV–VIS–NIR optical spectra show that the increase in Au doping into ZnO lattice promotes their transparency. Surface morphology and surface roughness are modified by the Au doping concentration. Magnetic measurement exhibited room temperature ferromagnetic ordering in undoped and Au doped ZnO thin films. The enhancement in saturation magnetization with increase in Au doping is due to creation of defects in ZnO lattice by Au doping due to oxygen vacancies and structural inhomogeneity which leads to development of bound magnetic polarons. Variation in AC conductivity with change in Au dopant percentage is studied using Jonscher's power law which is linked with barrier-hopping mechanism. Au doped ZnO is effective against gram positive and gram-negative bacteria. These have antimicrobial applications in biomedicine and environmental shield. Au doped ZnO thin films are beneficial in spin LEDs and switchable diodes. The Au doped ZnO photocatalyst can efficiently degrade methylene blue dye; hence, it can be used for the treatment of wastewater contamination.

Synthesis and Luminescence Properties of Two-Electron Bimetallic Cu-Ag and Cu-Au Nanoclusters via Copper Hydride Precursors.

The synthesis, structural characteristics, and photophysical properties of luminescent Cu-rich bimetallic superatomic clusters [Au@Cu12(S2CNnPr2)6(C≡CPh)4]+ (1a+), [Au@Cu12{S2P(OR)2}6(C≡CPh)4]+ (2+), (2a+ = iPr; 2b+ = nPr), [Au@Cu12{S2P(C2H4Ph)2}6(C≡CPh)4]+ (2c+), and [Ag@Cu12{S2P(OnPr)2}6(C≡CPh)4]+ (3+) were studied. Compositionally uniform clusters 1+-3+ were isolated from the reaction of dithiolato-stabilized, polyhydrido copper clusters with phenylacetylene in the presence of heterometal salts. By using X-ray diffraction, the structures of 1a+, 2a+, 2b+, and 3+ were able to be determined. ESI-mass spectrometry and elemental analysis confirmed their compositions and purity. The structural characteristics of these clusters are similar with respect to displaying gold (or silver)-centered Cu12 cuboctahedra surrounded by six dithiocarbamate/dithiophosph(in)ate and four alkynyl ligands. The doping of Au and Ag atoms into the polyhydrido copper nanoclusters significantly enhances their PL quantum yields from Ag@Cu12 (0.58%) to Au@Cu12 (55%) at ambient temperature in solution. In addition, the electrochemical properties of the new alloys were investigated by cyclic voltammetry.

Highly responsive ZnO nanorods array ultraviolet photodetectors modificated with reduced graphene oxide layer

In this paper, we demonstrate a new heterojunction ultraviolet (UV) photodetector in a superstrate configuration, i.e. glass/FTO/ZnO NRs/rGO/Au, constructed via the dip-coated method to form reduced graphene oxide (rGO) layer on the surface of ZnO nanorod arrays (NRs). The rGO compensates for surface oxygen vacancies by the oxygen-containing groups and improves the crystal properties of ZnO NRs after annealing. Furthermore, the carrier mobility and work function are effectively increased after Au doping. Under UV irradiation, the electron–hole pairs generated by ZnO NRs are separated with bias voltage, and the electrons and holes are collected via fluorine-doped tin dioxide (FTO) and rGO/Au, respectively. The rGO acts as a hole transport layer, which reduces the recombination of carriers and increases the current density, giving rise to a higher responsivity (67.48 A W−1 at −1.5 V bias) than pure ZnO NRs photodetectors.

Cubic aromaticity in ligand-stabilized doped Au superatoms.

The magnetic response of valence electrons in doped gold-based M@Au8L8 q superatoms (M = Pd, Pt, Ag, Au, Cd, Hg, Ir, and Rh; L = PPh3; and q = 0, +1, +2) is studied by calculating the gauge including magnetically induced currents (GIMIC) in the framework of the auxiliary density functional theory. The studied systems include 24 different combinations of the dopant, total cluster charge, and cluster structure (cubic-like or oblate). The magnetically induced currents (both diatropic and paratropic) are shown to be sensitive to the atomic structure of clusters, the number of superatomic electrons, and the chemical nature of the dopant metal. Among the cubic-like structures, the strongest aromaticity is observed in Pd- and Pt-doped M@Au8L8 0 clusters. Interestingly, Pd- and Pt-doping increases the aromaticity as compared to a similar all-gold eight-electron system Au9L8 +1. With the recent implementation of the GIMIC in the deMon2k code, we investigated the aromaticity in the cubic and butterfly-like M@Au8 core structures, doped with a single M atom from periods 5 and 6 of groups IX-XII. Surprisingly, the doping with Pd and Pt in the cubic structure increases the aromaticity compared to the pure Au case not only near the central atom but encompassing the whole metallic core, following the aromatic trend Pd > Pt > Au. These doped (Pd, Pt)@Au8 nanoclusters show a closed shell 1S21P6 superatom electronic structure corresponding to the cubic aromaticity rule 6n + 2.

Facile fabrication of novel nanostructured Au@PbI2 thin films and their structure, optical and NLO studies for higher order nonlinear applications

Herein, a facile fabrication of gold (Au) doped lead iodide (PbI2) (Au@PbI2) thin films have been achieved via spin-coating process from the microwave-synthesized Au@PbI2 nanosheets for the first time. Phase was confirmed from X-ray diffraction and FT-Raman spectroscopy analyses and approved 2H-Polytype of PbI2. The grain sizes were estimated via atomic force microscopy (AFM) and noticed between 13.5 and 9.2 nm for PbI2 and Au@PbI2 sample respectively. The Au doping in PbI2 was seen in EDX spectra and its homogeneity in SEM e-mapping. The nanostructured films fabrication was confirmed by SEM/AFM images. The transmittance of grown films is quite good in the visible region and reduction was seen in Au@PbI2 film compare to pristine. The energy gaps were estimated ~2.41 eV for pure and 2.45 eV for Au@PbI2 films. The value of refractive index was noticed ~2 in lower wavelength region. Dielectric constant and loss values were also determined. The highest values of nonlinear parameters like χ1, χ1 and n2 are found to be 0.68, 3.5 × 10−11 (esu) and 4.3 × 10−10 (esu) respectively at 1.11 eV of energy.

First-principles study on the magnetic properties of IB group transition metal-doped MoS2

In this paper, a first-principles calculation method based on density functional theory is used to study the effect of substitutional doping of Au, Ag, and Cu at Mo site on the magnetic properties of the single-layer MoS2system. It is found that the Au, Ag, and Cu-doped systems can all exhibit ferromagnetic properties at room temperature. The calculation of defect formation energy and hybrid orbital theory confirms that the system can exist stably. After comparing the energy difference, it is concluded that the magnetic properties of the doped system are more stable in the spin-polarized state. The magnetic moment contributed by impurity atoms is limited. The Mo and S atoms near the impurity atoms are induced by the impurity atoms, and the magnetic moment of the system is mainly produced by this method. There is a ferromagnetic coupling between impurity atoms and surrounding Mo atoms.

Au-doped BiVO4 nanostructure-based photoanode with enhanced photoelectrochemical solar water splitting and electrochemical energy storage ability

BiVO4 is an appropriate photoanode material for solar-powered photoelectrochemical (PEC) water splitting and electrochemical energy storage. However, it has a few drawbacks. Therefore, doping with noble metals is speculated to be a promising technique to overcome these. Moreover, the role of the doped noble metal in the improvement of the water oxidation kinetics and energy storage has not been studied adequately so far. In this study, we prepared Au-doped BiVO4 nanostructures using a simple template-free ultrasonication technique. The effect of Au doping on the optical properties and surface morphology of the BiVO4 nanostructures, and their performance as a photoanode for energy harvesting are explored comprehensively. The 5Au- BiVO4 photoelectrode displayed a considerable improvement (~29 times) in the PEC photocurrent density compared to that of the pure BiVO4 photoanode. Electrochemical impedance spectroscopy studies confirmed that the dopant improved the charge carrier density and acted as an electron donor. Furthermore, it was confirmed that the photocurrent density at 1.23 V vs. the reversible hydrogen electrode increased after Au doping. The supercapacitor properties of the 5Au-BiVO4 electrode were studied by cyclic voltammetry. At a 10 mV s−1 scan rate, the specific capacitance of the 5Au-BV electrode increased to ~2.1 times that of the pure electrode. The significantly improved PEC performance and supercapacitor properties of the 5Au-BiVO4 electrode are attributed to its higher conductivity, improved interfacial charge transfer at the surface of BiVO4, and the synergistic effect between the host and dopant.

Optical and electrical characterization of organic solar cells obtained using gold and silver metal nanoparticles

Light absorption of metal nanoparticles and charge separation are two major factor for the efficiency improvement in organic solar cells. Metallic nanoparticles may exhibit surface plasmons when exposed to light. This special optical properties of metal nanoparticles make them useful in photonics, electronics and biomedical applications. In this study, gold and silver nanoparticles increased the surface roughness of the active layer. The absorption, SEM, AFM, XRD measurements of 1% ratio gold and silver nanoparticles doped active layers were carried out. Optical band gap of these films was calculated with using absorption measurements. Then, ITO/PEDOT:PSS/P3HT:PCBM:Au/LiF/Al and ITO/PEDOT:PSS/P3HT:PCBM:Ag/LiF /Al organic solar cells were obtained. It was calculated the solar cells parameters such as short -circuit current density (Jsc), open - circuit voltage (Voc), fill factor (FF) and power conversion efficiency (PCE) from current density–voltage (J-V) measurements at the room temperature. The experimental results revealed that the presence of Au and Ag nanoparticles (NPs) in the ITO/PEDOT:PSS/P3HT:PCBM/Al solar cell improved its performance with respect to undoped solar cells. For example, the power conversion efficiency was increased from 2.11% to 2.55% when doping 1 wt% of Au NPs to P3HT:PCBM and to 2.23% when doping of Ag NPs to P3HT:PCBM. This was attributed to increase of the light absorption in the presence of Au and Ag NPs doping. However, the optical band gap of films have not changed significiantly after the NPs doping.