Au Doping Research Articles

Experimental and density functional theory study of the gas sensing property of Pt and Au doped WS2 to partial discharge gas CO in air switchgear

This work aims to investigate the detection performance of WS2 and its doped gas sensitive materials for carbon monoxide (CO), one of the most important characteristic gases of partial discharge in air switchgear.Its accurate monitoring can be an effective evaluation of the operating condition of air switchgear. Three gas-sensitive materials were synthesized using the hydrothermal method: WS2, Pt-WS2, and Au-WS2. The materials were characterized through XRD, SEM, and XPS, followed by an evaluation of their sensing performance for CO gas. The findings revealed that the gas sensitivity of WS2 was significantly enhanced through doping with Pt and Au. At a CO concentration of 10 ppm, the response sensitivity of the Pt-WS2 sensor reached 4.03, while that of the Au-WS2 sensor was measured at 2.68—both representing an increase by a factor of 3.52 compared to intrinsic WS2 sensors. Moreover, the response recovery time for the Au-WS2 sensor was found to be 20–30 s faster than that observed in Pt-WS2 sensors. The mechanisms underlying the enhancement in CO adsorption on WS2 due to Pt and Au doping were investigated based on density functional theory calculations encompassing band structure analysis, density of states assessment, adsorption distance measurement, and adsorption energy evaluation. This study posits that both Pt-WS2 and Au-WS2 can be used for the detection of partial discharge gas CO in air switchgear.

Preparation of Au/α‐Fe2O3 Electrode for the Detection of Dopamine

AbstractIn this study, Au/α‐Fe2O3 sensing material was synthesized and used as the working electrode for dopamine sensing. The Au/α‐Fe2O3 composites were prepared with various loadings (0.5 %, 1 %, and 3 %) to enhance their sensing properties. All three composites were tested for dopamine sensing, with 1 % Au/α‐Fe2O3 showing the best response. The Au/α‐Fe2O3 composites were characterized using XRD, TEM, and SEM to confirm successful doping of Au on the iron oxide surface. The CV plot obtained by plotting Cyclic Voltammetry (CV) vs. dopamine (DA) was linear (R2=0.9872) for DA concentrations ranging from 6.25 μM–200 μM on 1 % Au/α‐Fe2O3. Similarly, the DPV plot between DPV vs. DA was linear (R2=0.9895) for the same DA concentration range on 1 % Au/α‐Fe2O3, with a detection limit of 0.19 μM. Interference and stability experiments were conducted with dopamine (DA), ascorbic acid (AA), and uric acid (UA). The results showed that DA sensing was not affected by the other two substances for up to 14 days. The signal results indicated that the current intensity remained at 90.75 % of the original, proving that this material has good stability.

Rational design of Au-Bi bimetallic nanozyme for NIR-II laser mediated multifunctional combined tumor therapy

To maximize the therapeutic effects and minimize the adverse effects of synergistic tumor therapies, a multifunctional nanozyme Au-Bi/ZIF-8@DOX@HA (ABZ@DOX@HA) was designed and synthesized through the Au and Bi bimetallic doping of ZIF-8, loading of the DOX, and modifying with hyaluronic acid (HA). The ABZ@DOX@HA nanoparticles (NPs) could simulate the enzymatic activities of glucose oxidase (GOx) and peroxidase (POD). Upon irradiated by near-infrared region (NIR-II) laser, the strong synergism of the photothermal abilities of the loaded Au and Bi nanodots accelerated the collapse of the ABZ structure at the tumor site considerably and released Au, Bi nanodots and DOX. The results in vitro and in vivo proved that ABZ@DOX@HA nanozyme could effectively exert the combined tumor therapy of starvation treatment, photothermal therapy (PTT), chemodynamic therapy (CDT) and chemotherapy. The current research provides a new strategy to address the inherent challenges of easy clearance and short blood circulation of small-sized NPs during the treatment of tumors with nanomedicine, as well as the aggregation and oxidation of inorganic nanodots.

A minimally invasive sensing system based on hydrogel microneedle patches and Au/Cu2O nanospheres modified screen-printed carbon electrode for glucose monitoring in interstitial skin fluid

Glucose monitoring in interstitial skin fluid (ISF) has become a novel approach for diabetes management. In this paper, a minimally invasive sensing system consisted of methacrylated hyaluronic acid (MeHA) based microneedle patches and Au/Cu2O nanospheres modified screen-printed carbon electrode (SPCE) was designed for glucose monitoring in the ISF of living mice. The highly swellable and biocompatible MeHA microneedle patches can effectively extract ISF from the skin, barely cause pain to the living mice. The glucose level in the extracted ISF was detected via an enzyme-free electrochemical sensor using the Au/Cu2O nanospheres as the electrocatalyst. The doping of Au into Cu2O resulted in a highly conductive and active electrocatalyst for glucose oxidation, which improved the sensing performance of glucose sensor. A wide linear range (0.02 – 6 mM), low detection limit (0.018 mM), and high sensitivity (110.38 μA mM−1 cm−2) were obtained under the optimized condition. The obtained results exhibited a comparable trend to those obtained from commercial glucometers. We have combined successfully MeHA patches for ISF extraction with enzyme-free electrochemical glucose sensor. Therefore, this novel sensing system holds great potential for diabetes management in a minimally invasive manner.

Metal-Organic Framework-Derived Au-Doped In2O3 Nanotubes for Monitoring CO at the ppb Level.

Achieving selective detection of ppb-level CO is important for air quality testing at industrial sites to ensure personal safety. Noble metal doping enhances charge transfer, which in turn reduces the detection limit of metal oxide gas sensors. In this work, metal-organic framework-derived Au-doped In2O3 nanotubes with high electrical conductivity are synthesized by pyrolysis of the Au-doped metal-organic framework (In-MIL-68) as a template. Gas-sensing experiments reveal that the detection limit of 0.2% Au-doped In2O3 nanotubes (0.2% Au, mass fraction) is as low as 750 ppb. Meanwhile, the sensing material shows a response value of 18.2 to 50 ppm of CO at 240 °C, which is about 2.8 times higher than that of pure In2O3. Meanwhile, the response and recovery times are short (37 s/86 s). The gas-sensing mechanism of CO is uncovered by in situ DRIFTS through the reaction intermediates. In addition, first-principles calculations suggest that Au doping of In2O3 significantly enhances its adsorption energy for CO and improves the electron transfer properties. This study reveals a novel synthesis pathway for Au-doped In2O3 nanotubular structures and their potential application in low concentration CO detection.

Facile synthesis of highly active PdAu alloy nanochains for alcohol oxidation electrocatalysis

An efficacious strategy to enhance the activity and stability of electrocatalysts for alcohol oxidation reactions is the formation of alloys of palladium with oxygenophilic metals. In this study, Palladium nano chains with an average diameter of approximately 4.4 nm were synthesized via a one-step hydrothermal approach, employing creatine as the structural guide. The one-dimensional structure yielded a huge electrochemically active area (84.5 m2 g−1) and good electrical conductivity. the mass activity of Pd87Au13 NCs for alkaline ethanol oxidation reaction was 4050 mA mgPd+Au−1, which is 7.32 times higher thancommercial Pd/C, and also maintains a high residual current density after 20000 s stability test. In addition, the excellent performance of the material was demonstrated during the oxidation of ethylene glycol and glycerol. The improved catalytic performance is owed to the interconnected chain shape providing fast electron transport channels, and the Au doping not only optimizes the electronic structure of Pd but also has a bifunctional effect, which effectively removes the carbon-containing intermediates generated by Pd during alcohol oxidation, thus improving its resistance to poisoning and stability.

Effects of Au doping on the adsorption of xanthate on pyrite surface in presence of H2O: A DFT study

Despite density functional theory (DFT) has been widely applied in the study of Au-doped pyrite, effects of Au doping on the structural properties and floatability of pyrite still remain uncertain. Most of the previous studies were carried out in vacuum disregarding the existence of water molecules, which were inconsistent with the real flotation system. This work aims to study the adsorption behavior of ethyl xanthate on the surface of perfect pyrite and Au-doped pyrite in presence of water molecules through DFT calculations. It was found that the doped Au expanded the lattice of pyrite (100) surface, with enhanced conductivity and chemical reactivity. After Au-doping, the population and covalence level of Fe-S bond of pyrite was reduced, making Fe atoms prone to interact with water molecules and xanthate. The binding energy and density of states (DOS) analysis indicated that Au-doping enhanced the binding ability of xanthate with pyrite surface more significantly than water molecules. Therefore, Au-doping promoted the adsorption of xanthate on pyrite surface in presence of water molecules. This study is of guiding significance for investigating the flotation behavior of Au-doped pyrite and flotation reagents design.

Biosynthesis of Gold- and Silver-Incorporated Carbon-Based Zinc Oxide Nanocomposites for the Photodegradation of Textile Dyes and Various Pharmaceuticals

Wastewater contaminated with dyes from the textile industry has been at the forefront in the last few decades, thus, it is imperative to find treatment methods that are safe and efficient. In this study, C. benghalensis plant extracts were used to synthesise by mass 20 mg/80 mg zinc oxide–carbon spheres (20/80 ZnO–CSs) nanocomposites, and the incorporation of the nanocomposites with 1% silver (1% Ag–ZnO–CSs) and 1% gold (1% Au–ZnO–CSs) was conducted. The impact of Ag and Au dopants on the morphological, optical, and photocatalytic properties of these nanocomposites in comparison to 20/80 ZnO–CSs was investigated. TEM, XRD, UV-vis, FTIR, TGA, and BET revealed various properties for these nanocomposites. TEM analysis revealed spherical particles with size distributions of 40–80 nm, 50–200 nm, and 50–250 nm for 1% Ag–ZnO–CSs, 1% Au–ZnO–CSs, and 20/80 ZnO–CSs, respectively. XRD data showed peaks corresponding to Ag, Au, ZnO, and CSs in all nanocomposites. TGA analysis reported a highly thermally stable material in ZnO-CS. The photocatalytic testing showed the 1% Au–ZnO–CSs to be the most efficient catalyst with a 98% degradation for MB textile dye. Moreover, 1% Au–ZnO–CSs also exhibited high degradation percentages for various pharmaceuticals. The material could not be reused and the trapping studies demonstrated that both OH• radicals and the e− play a crucial role in the degradation of the MB. The photocatalyst in this study demonstrated effectiveness and high flexibility in degrading diverse contaminants.

Identifying the distinct roles of dual dopants in stabilizing the platinum-nickel nanowire catalyst for durable fuel cell

Stabilizing active PtNi alloy catalyst toward oxygen reduction reaction is essential for fuel cell. Doping of specific metals is an empirical strategy, however, the atomistic insight into how dopant boosts the stability of PtNi catalyst still remains elusive. Here, with typical examples of Mo and Au dopants, we identify the distinct roles of Mo and Au in stabilizing PtNi nanowires catalysts. Specifically, due to the stronger interaction between atomic orbital for Ni-Mo and Pt-Au, the Mo dopant mainly suppresses the outward diffusion of Ni atoms while the Au dopant contributes to the stabilization of surface Pt overlayer. Inspired by this atomistic understanding, we rationally construct the PtNiMoAu nanowires by integrating the different functions of Mo and Au into one entity. Such catalyst assembled in fuel cell cathode thus presents both remarkable activity and durability, even surpassing the United States Department of Energy technical targets for 2025.

Synergistic sensitization effects of single-atom gold and cerium dopants on mesoporous SnO2 nanospheres for enhanced volatile sulfur compound sensing

A concept of synergistic sensitization effects involving single-atom Au and Ce dopants on mesoporous SnO2 nanospheres is proposed for ultrasensitive and real-time monitoring of ppb-level volatile sulfur compounds.

Multifunctional nanoplatform based on tetragonal BaTiO3-Au@polydopamine for computed tomography imaging-guided photothermal synergistic and enhanced piezocatalytic cancer therapy

Non-centrosymmetric tetragonal barium titanate nanocrystals have the potential to serve as piezoelectric catalysts in cancer therapy. When exposed to ultrasound irradiation, BaTiO3 can generate reactive oxygen species with a noninvasive and deep tissue-penetrating approach. However, the application of BaTiO3 in cancer nanomedicine is limited by their biosafety, biocompatibility, and dosage efficiency. To explore the potential application of BaTiO3 in nanomedical cancer treatment, we introduced ultra-small Au nanoparticles onto the surface of BaTiO3 to enhance the piezoelectric catalytic performance. Additionally, we also coated the BaTiO3 with polydopamine to improve their biosafety and biocompatibility. This led to the preparation of a novel multifunctional BaTiO3-based nanoplatform called BTAPs. In vitro and in vivo experiments demonstrated that the incorporation of Au dopants and polydopamine coating successfully improved the piezoelectric catalysis properties and biocompatibility of BaTiO3. Compared with unmodified BaTiO3, BTAPs achieved a similar piezoelectric catalytic effect at a low dose (0.3 mg ml−1 in vitro and 10 mg kg−1 in vivo). Moreover, BTAPs also exhibited enhanced properties in computed tomography imaging and photothermal effects in vivo. Therefore, BTAPs offer valuable insights into the advantages and limitations of piezoelectric catalytic nanomedicine in cancer treatment.

Neutral pH photoenzymatic activity of Au-doped g-C3N4 nanosheet for colorimetric detection of total antioxidant capacity in food samples

Total antioxidant capacity (TAC) is vital for food quality evaluation. The emergence of various nanozymes with TMB as substrate offered a new avenue for TAC detection due to simple operation and fast response, but a long-standing challenge is its low activity at physiological pH, which may account for the discrepancy between the measured TAC and the actual antioxidant capacity in vivo. Herein, Au doping was explored to break the pH limitation of g-C3N4 nanosheets (CNNS) photozyme. The catalytic activities of Au@CNNS at pH 4.0 and 7.4 were 14.9- and 6.2-fold higher than that of CNNS at pH 4. The neutral pH photozymatic activity (photosensitized oxidation of TMB, oxidase mimic) of Au@CNNS was explored for sensitivity TAC detection (LOD: 1.0 μM TE), which featured more convenient operations and higher sensitivity over the DPPH assay. The proposed Au@CNNS-based photozymatic colorimetric method was explored for accurate detection of TAC in drinks and juices.

Band gap engineering of Au doping and Au – N codoping into anatase TiO2 for enhancing the visible light photocatalytic performance

We investigate anatase TiO2 doping with Au to determine the change in the band gap energy and optoelectronic properties using experimental and theoretical analysis. The structural analysis using XRD patterns revealed that the synthesized materials primarily exhibited an anatase phase of TiO2, with no impurity peaks observed. However, as the concentration of Au increased, additional diffraction peaks corresponding to Au crystalline phases were detected, indicating successful doping. Furthermore, the crystallite size was found to decrease with increasing Au concentration. We observe that the band gap reduces through substitution of Au into the TiO2 lattice from 3.09 eV to 2.78 eV, demonstrating the feasibility of bandgap tuning of the TiO2 system. A redshift for Au doped TiO2 is observed from absorption spectroscopy and optical absorption intensity using hybrid density functional theory, facilitating visible light absorption, although with potential electron-hole recombination limitations. To enhance a visible light photocatalytic activity for water splitting, we extend our work to explore the impact of N and Au codoping into TiO2 lattice. It reveals that the combination between N and Au leads to a suitable reduction in the band gap width of pure TiO2. Interestingly, Au–N codoping may decrease the effect of photogenerated carriers, produce a new optical absorption feature in the visible region, and enhance the photocatalytic performance of TiO2. This codoping configuration is also a promising photocatalyst for the decomposition of water using visible light without inducing unoccupied states.

Effect of atomic doping on the adsorption of Hg by WS2

With the development of industrialization, the use of mercury in industry has become more and more widespread, causing serious impacts on the environment. It is therefore urgent to find new effective ways to combat mercury pollution. In this paper, The effect of C, O, P, Ni and Au doping on the adsorption of Hg atoms by WS2 has been investigated based on the first nature principle of density functional theory. The electronic structures and optical properties of the adsorbed systems were calculated after atomic doping. The results show that the absolute value of the adsorption energy of the intrinsic adsorption system is small and does not favour the adsorption of Hg on WS2. However, after C, P, Ni and Au doping, the adsorption energy of the system is significantly increased and a strong charge transfer between WS2 and Hg atoms occurs, as well as a significant change in the band gap of the structure. This suggests that atomic doping favors the adsorption of Hg by WS2. The effect of O doping on the adsorption system is not significant. In addition, a study of the optical properties revealed that the static dielectric constants of the system appeared to increase to varying degrees after the doping of the atoms. The doping of P, Ni and Au atoms increases the light absorption coefficient and contributes to the photocatalytic efficiency of the structures. The doped atoms cause a red shift in the reflectivity peak of the adsorbed system. In summary, the doping of C, P, Ni and Au enhances the adsorption of Hg atoms on WS2. O doping has less effect on the adsorption of Hg on WS2.

Probing the Fluorescence Intermittency of Bimetallic Nanoclusters using Single-Molecule Fluorescence Spectroscopy.

Single-molecule spectroscopy (SMS) is a unique and competent technique to study molecule dynamics and sense biomolecules precisely. The design of an ultrahigh-stability single fluorophore probe with excellent photostability and long-lived dark transient states for single-molecule fluorescence microscopy is challenging. Here, we found that the photostability of bimetallic AuAg28 nanoclusters is better than monometallic Ag29 nanoclusters. The photon antibunching experiments unveiled exceptional brightness and remarkable photostability with high survival times of up to 218 s with minimal blinking. AuAg28 NCs exhibited longer "on" times and shorter "off" times as compared to Ag29 NCs. The statistical analysis was performed on at least 100 molecules that showed single-step photobleaching and almost a 5-fold enhancement in intensity on Au doping in Ag29 NCs. The distinctive and tunable photophysics of metal NCs can offer huge potential in pushing single-molecule dynamic measurements to be carried out biologically.

Effect of ratio gold nanoparticles on the properties and efficiency photovoltaic of thin films of amorphous tungsten trioxide

At a substrate temperature of 320 o C, a chemical spray pyrolysis approach was applied. to create tungsten oxide thin films on glass substrates with varying Au nanoparticle doping concentrations (0, 0.04 and 0.08 M) that have a thickness of roughly 250 nm. Investigated were the structural and optical characteristics. The films were amorphous to the pure films at the substrate temperature (320 °C), according to X-ray diffraction and remain so even after adding GNPs, because the WO3 structure is amorphous in all samples, whereas the cubic structure of the gold nanoparticles. The morphology of the films was examined using atomic force microscopy (AFM), which showed a decrease in the grain size of the films doped with gold compared to the thin films before the doping process. a UV-Vis spectrophotometer was used to examine the membranes' optical characteristics between the wavelengths of (300-1000) nm. was the optical energy gap of the films (3.23) eV for tungsten oxide film and decreased after adding nanoscale gold to (3.04, 2.95) eV for films doped with different proportions of Au NPs (0.04, 0.08 M), respectively. Hall testing confirms that with 8 (mM) Gold (Au) doping, WO3 material of the n type was obtained with a maximum carrier mobility of 219.92(cm2 /Vs) and conductivity of 6.52 (Ω.cm)-1 . The I-V characteristics of the photovoltaic formed under illumination were determined by measuring the incident power density (100 mW/cm2 ) at varied Au doping levels.

Molecular dynamics study influence of factors on the structure, phase transition, and crystallization of the Ag1-xAux, x = 0.25, 0.5, 0.75 alloy

In this research, Molecular Dynamics (MD) method simulations were used to study the influence factors such as concentration of Au doping in Ag1-xAux alloy, atomic number, temperature, annealing time on the structure, transition process phase, and crystallization of Ag1-xAux alloy by choosing Sutton-Chen (SC) interaction potential field and periodic boundary conditions. The results show that, when the concentration of Au doping in Ag1-xAux alloy increases, the number of crystallization processes decreases at temperature, while the number of atoms and the annealing time at the glass temperature Tg = 900 K increase, the process results for crystallization increase. The crystallization process is expressed through the number of structural units Hexagonal Close Packed (HCP), Body-Centered Cubic (BCC) and Amorphous (Amor), and the total energy of the system (Etot). The results show that there is a significant influence of doping concentration, atomic number, temperature, and annealing time. Then the length of the links Ag-Ag, and Au-Au varies greatly. The link Ag-Au remains constant because with the r = 2.82 Å value, the total energy of the system and the size of the material change very little. During the phase transition, the length of the links (r), the total energy of the system, size (Etot), and the number of FCC, HCP, BCC, and Amor structural units change significantly. The results obtained on Ag1-xAux alloy can serve as a basis for future experimental studies.

Au- or Ag-Decorated ZnO-Rod/rGO Nanocomposite with Enhanced Room-Temperature NO2-Sensing Performance.

To improve the gas sensitivity of reduced oxide graphene (rGO)-based NO2 room-temperature sensors, different contents (0-3 wt%) of rGO, ZnO rods, and noble metal nanoparticles (Au or Ag NPs) were synthesized to construct ternary hybrids that combine the advantages of each component. The prepared ZnO rods had a diameter of around 200 nm and a length of about 2 μm. Au or Ag NPs with diameters of 20-30 nm were loaded on the ZnO-rod/rGO hybrid. It was found that rGO simply connects the monodispersed ZnO rods and does not change the morphology of ZnO rods. In addition, the rod-like ZnO prevents rGO stacking and makes nanocomposite-based ZnO/rGO achieve a porous structure, which facilitates the diffusion of gas molecules. The sensors' gas-sensing properties for NO2 were evaluated. The results reveal that Ag@ZnO rods-2% rGO and Au@ZnO rods-2% rGO perform better in low concentrations of NO2 gas, with greater response and shorter recovery time at the ambient temperature. The response and recovery times with 15 ppm NO2 were 132 s, 139 s and 108 s, 120 s, and the sensitivity values were 2.26 and 2.87, respectively. The synergistic impact of ZnO and Au (Ag) doping was proposed to explain the improved gas sensing. The p-n junction formed on the ZnO and rGO interface and the catalytic effects of Au (Ag) NPs are the main reasons for the enhanced sensitivity of Au (Ag)@ZnO rods-2% rGO.

The effect of trace solute Au atoms on the phase structure, mechanical and self-lubricating properties of MoSi2 films

To overcome the high friction coefficient and low toughness bottleneck of MoSi2 used as protective films for moving parts, a novel strategy of doping and alloying through magnetron sputtering to build self-lubricating Mo-Si-Au solid solution film has been proposed. Herein, a series of MoSi2 films with different Au contents were prepared, and their phase structure, mechanical and tribological properties were investigated. The results indicate that when Au/Mo atomic ratio R = 0.10, Au atoms tend to replace Si atoms to form Mo-Si-Au solid solution film. Nevertheless, the Au atom would segregate to form a nanocomposite at R = 0.20. The nanoindentation test shows that the Mo-Si-Au solid solution film possesses the largest hardness, which is mainly attributed to the solid solution strengthening. The result of tribological testing exhibits that Au doping can significantly reduce the friction coefficient of MoSi2. More importantly, Mo-Si-Au solid solution film is realized with a lower coefficient of friction (∼0.08), which is ascribed to the formation of MoSiOx lubricating phase during the sliding induced solute Au atoms. Accordingly, the research would provide a considerable theoretical and technical foundation for the development of novel self-lubricating films with excellent mechanical properties.

Charge transport properties of interstitially doped graphene: a first-principles study

The role of interstitial atomic doping on transport properties of graphene was systematically studied using first-principles density functional theory (DFT). The study revealed that interstitial Au doping results in a p-type transfer of holes to graphene as the dopant concentration increases to 25%, with the Dirac point shifting to the Fermi level and localised states of atomic dopants appearing at the Fermi level and at energy of −1 eV. Ca, Ag and Al interstitial doping induces an n-type transfer of electrons to graphene with the Dirac point moving away from the Fermi level and localised states appearing at the Fermi level and at energy levels of ∼2 eV for Ca, around −3.5 eV for Ag, −3.5 eV and ∼1.6 eV for Al. As the dopant concentration increases further to 50%, the number of holes (or electrons) decreases for all dopants, except for Ca, as the localised state at the Fermi level disappears, and the Dirac point returns towards the Fermi level. Our research provides insights into how to reconcile the localised state and the number of charge carriers that play a significant role in the transport properties of interstitial doped graphene.