Incorporation Of Au Research Articles

Rapid removal and catalytic decomposition of nitrate in anion-exchange resin containing gold nanoparticles toward purification of groundwater

We investigated the catalytic reduction of NO3– in various single-metal-introduced anion-exchange resins (AERs) in 1 bar H2 and observed that the reaction proceeded successfully. Among the metals considered in this study, Au was optimal in terms of catalytic activity and ease of catalyst preparation, whereas Ru exhibited the highest activity. The AER with Au (Au@AER) containing the optimal amount of Au (0.3mmol/g) decomposed 0.38mmol/g of NO3– primarily into N2O under optimized reaction conditions (80°C and 5 h). The decomposition amount corresponded to 41 % conversion. The incorporation of Au into the AER increased its ion-exchange capacity from 1.18 (pristine AER) to 1.46mmol/g (Au@AER); in contrast, the ion-exchange equilibrium constant decreased from 1.4 to 0.83 L mol−1 owing to the change in the structure of the anion-exchange sites in the AER. Au@AER was reusable for ion-exchange removal and catalytic decomposition of NO3– up to five times without performance degradation.

High performance symmetric supercapacitors based on Au incorporated CrN thin films fabricated by reactive magnetron sputtering

Recently, transition metal nitrides are being investigated extensively as potential supercapacitor material. In the present study, Au incorporated CrN (Au_CrN) thin films have been synthesized using reactive magnetron co-sputtering technique for application as supercapacitor electrode material. Films have been prepared at different Ar to N2 flow rates keeping total deposition pressure constant to achieve the required structural phase in the sample. Electrochemical properties of the deposited materials have been investigated with a three-electrode system in 0.5 M H2SO4 aqueous electrolyte. The CrN thin film deposited under 3:1 Ar: N2 partial pressure or flow rate ratio shows the highest specific capacitance. Upon Au incorporation, the film shows an areal capacitance of 56.8 mFcm−2 at 1.0 mAcm−2discharge current density which is an almost nine-fold enhancement in specific capacitance value compared to pristine CrN sample. Symmetric supercapacitors have also been developed by sandwiching two identical Au_CrN thin film electrodes, which have found to deliver excellent specific capacitance of 86.03 mFcm−2at 1.0 mAcm−2 discharge current density with no decline in capacitance value till 20,000 cycles. Furthermore, it can deliver a high energy density of 52.02mWhcm−2and a power density of 0.12mWcm−2. The electrochemical properties of the supercapacitors fabricated with the Au_CrN thin film electrodes are found to be better than most of the results reported so far in the literature with CrN electrodes. Results of the present study clearly demonstrate that these Au enhanced CrN films prepared by easily scalable and highly reproducible magnetron sputtering technique have great potential as a high capacitance supercapacitor electrode material.

Ultrasensitive detection of xylene gas by cauliflower-like Au-TiO2 core-shell nanoparticles

TiO2 nanoparticles (NPs) and Au-TiO2 core-shell NPs (C-S NPs) were synthesized for xylene gas detection. Morphological, phase, and chemical studies demonstrated the successful generation of Au-TiO2 C-S NPs with a cauliflower-like morphology and desired composition. Also, the surface area of TiO2 NPs was 8.46, which increased to 23.88 m2/g for Au-TiO2 C-S NPs, due to the creation of a porous TiO2 shell around the Au core. The response of the TiO2 NPs to 50 ppm xylene was 14.19 at 500°C, while it increased to 165.77 at a lower temperature (450°C). Furthermore, while the TiO2 NPs gas sensor has no selectivity to xylene gas, the TiO2 C-S NP gas sensor exhibited excellent selectivity. Overall, incorporation of Au in TiO2 in the form of a C-S structure improved the performance of the sensor to sense xylene. Improved xylene sensing for the TiO2 C-S NPs stemmed from the high surface area and porous nature, oxygen defects, and formation of Au-TiO2 Schottky barriers. This research demonstrates the development of high-output xylene sensors by means of Au-TiO2 with a C-S structure.

Gold and Arsenic in Pyrite and Marcasite: Hydrothermal Experiment and Implications to Natural Ore-Stage Sulfides

Hydrothermal synthesis experiments were performed in order to quantify the states of Au and As in pyrite and marcasite. The experiments were performed at 350 °C/500 bar and 490 °C/1000 bar (pyrite–pyrrhotite buffer, C(NaCl) = 15 and 35 wt.%). The synthesis products were studied by EPMA, LA-ICP-MS, and EBSD. The EPMA was applied for simultaneous determinations of Au, As, Fe, and S, with a Au detection limit of 45–48 ppm (3σ). The analyses were performed along profiles across zonal grains. The concentrations of As and Au up to 5 wt.% and 8000 ppm, respectively, were determined in pyrite and up to 6 wt.% and 1300 ppm in marcasite. In pyrite, the Au concentration decreases with fluid salinity and temperature increases. Strong positive Au–As correlation and strong negative Au–Fe and As–S correlation were identified in pyrite. Comparison of the correlations with theoretical lines implies Au–As clustering. The cluster stoichiometry is inferred to be [AuAs10]. Most probably, As in pyrite presents in the form of clusters and in the As→S solid solution. Incorporation of Au in As-rich pyrite can be controlled by the reductive deposition mechanism. In marcasite, the concentrations of Au are not correlated with the As content. The [AuAs10] clusters enrich the {210}, {113}, and {111} pyrite faces, where the former exhibits the highest affinity to Au and As. The affinity of {110} and {100} forms to Au and As is lower. Implication of the experimental results to data for natural auriferous pyrite shows that the increase of Au content at C(As) > 0.5–1 wt.% is caused by the incorporation of the Au-As clusters, but not because of the formation of Au→Fe solid solution. Therefore, the concentration of “invisible” gold in pyrite is dictated solely by the hydrothermal fluid chemistry and subsequent ore transformations.

Anchoring bimetallic PtAu nanoparticles on hierarchical zeolite as efficient electrocatalyst for the enhancement of ethanol electrooxidation

Zeolite materials as nanoreactor are promising candidates as catalysts for the oxidation of alcohol fuels. In the present work, the hierarchical zeolite was prepared via a hydrothermal technique. Then, the bimetallic Pt-Au-zeolite composite as electrocatalysts were synthesized by co-precipitation route. The surface morphology, composition and structure of the resulting composite were investigated by FE-SEM, EDS, XRD, XPS, BET&BJH and FT-IR. The catalytic performance of the composite has been examined in ethanol electrooxidation reactions under alkaline media. Pt-Au-zeolite exhibits superior selectivity for the electrooxidation of the ethanol, outperforming both conventional Au and Pt nanoparticles supported on zeolite crystals catalyst. The peak electrooxidation current of ethanol with Pt-Au-zeolite catalyst is 3.63 times that of Pt-zeolite with a scan rate of 50 mVs−1, which is due to the synergistic effect of Au and Pt in zeolite framework. It could be attributed to the incorporation of Au and Pt into zeolite framework, which was beneficial to the charge transferring the surface of Pt-Au-zeolite electrocatalyst and facilitated the ethanol oxidation. Besides, the significant electrochemical activity can be due to the production of OH–, which leads to the species present on the surface of the electrocatalysts during the activation process that controlled by the zeolite framework.

Sonochemical Synthesis, Characterization, and Photocatalytic Performance Evaluation of Au/ZnO Nanocomposite for Methyl Orange Degradation

This study examines the impact of gold (Au) incorporation on zinc oxide (ZnO) nanoparticles. Both pure ZnO and Au/ZnO nanocomposite have been synthesized using a unique and environmentally friendly sonochemical approach. The as-synthesized Au/ZnO nanocomposite was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and ultraviolet-visible (UV-vis) spectroscopic techniques. Under UV-visible irradiation, the photocatalytic effectiveness of ZnO nanoparticles and Au/ZnO nanocomposites for the degradation of dye was examined. The results demonstrated that the nanocomposite has greater photocatalytic activity than ZnO nanoparticles. This is due to the effective electron transfer from ZnO to Au prolonging the lifetime of photogenerated holes, which play the most important role in the dye degradation process.

AgAuS Quantum Dots as a Highly Efficient Near-Infrared Electrochemiluminescence Emitter for the Ultrasensitive Detection of MicroRNA.

Herein, the novel alloyed silver gold sulfur quantum dots (AgAuS QDs) with highly efficient near-infrared (NIR) electrochemiluminescence (ECL) emission at 707 nm were successfully prepared to construct a biosensing platform for ultrasensitive detection of microRNA-222 (miRNA-222). Interestingly, AgAuS QDs revealed excellent ECL efficiency (34.91%) compared to that of Ag2S QDs (10.30%), versus the standard [Ru(bpy)3]2+/S2O82- system, which benefited from the advantages of abundant surface defects and narrow bandgaps by Au incorporation. Additionally, an improved localized catalytic hairpin self-assembly (L-CHA) system was developed to display an increased reaction speed by improving the local concentration of DNA strands, which addressed the obstacles of time-consuming traditional CHA systems. As a proof of concept, based on AgAuS QDs as an ECL emitter and improved localized CHA systems as a signal amplification strategy, a "signal on-off" ECL biosensor was developed to exhibit a superior reaction rate and excellent sensitivity with a detection limit of 10.5 aM for the target miRNA-222, which was further employed for the analysis of miRNA-222 from cancer cell (MHCC-97L) lysate. This work advances the exploration of highly efficient NIR ECL emitters to construct an ultrasensitive biosensor for the detection of biomolecules in disease diagnosis and NIR biological imaging.

Coupling and decoupling of Au and As in pyrite from Carlin-type Au deposits, southwest China

The low-temperature geochemistry of gold (Au) and arsenic (As) in pyrite from Carlin-type Au deposits is significant for understanding the enrichment mechanisms of Au in pyrite, but remains poorly understood due to the complex processes that lead to the precipitation of micron-scale pyrite grains. This paper concerns the geochemical behaviors of Au and As during the precipitation of pyrite from six Carlin-type Au deposits (the Nibao, Shuiyindong, Banqi, Jinya, Yata, and Zimudang deposits), southwest China. These deposits are located in different locations and ore-bearing horizons of the Youjiang Basin. Arsenian pyrite and/or arsenopyrite are the dominant Au-bearing minerals. Gold-bearing pyrite grains are typically zoned (core, intermediate, and rim), with multiple, oscillatory banded sub-zones. In situ analysis demonstrates that invisible Au exists mainly as cationic Au+ in the growth zones of pyrite. Gold and As are positively correlated (i.e., coupled) in the Nibao and Shuiyindong deposits, negatively correlated in the Banqi, Jinya, and Yata deposits, and poorly correlated in the Zimudang deposit. Arsenic and S substitution in pyrite and the presence of a reduced fluid promoted the incorporation of Au, resulting in the coupling of Au and As. The Au precipitation was affected by changes in the physicochemical conditions of the hydrothermal systems, independent of the As concentration, resulting in decoupling of Au and As. As such, invisible Au precipitation is controlled by the extrinsic physicochemical conditions of the ore-forming fluids and microscopic reactions at the fluid–mineral interface, and also the episodic incursion of Au-rich hydrothermal fluids. High As contents in pyrite favor Au incorporation, but are not solely responsible for Au enrichment. Gold and As contents in pyrite in Carlin-type Au deposits may be coupled or decoupled.

Enhanced photodetector performance of SnO2/NiO heterojunction via Au incorporation

Heterojunctions are known to have trap states and defects that are detrimental to the light responses, especially slowing down the rise and decay time. To address these issues in the charge transfer process, SnO2/NiO heterojunction was modified by incorporating Au at the surface and interface of different devices. The rectifying SnO2/NiO diode showed self-powered photodetector (SPD) characteristics when illuminated by 365 nm light and the responsivity obtained was 3 µA W−1. The 5 nm Au surface decorated SnO2/NiO diode showed the highest rectification ratio, 42.8 and the 2 nm Au decorated device showed 10.6 µA photocurrent generation. The 2 and 5 nm thick Au surface decoration resulted in the formation of nano-Schottky junctions with NiO. The embedding of Au at the interface of the SnO2/NiO diode showed a decrease in diode rectification. Two methods are used for Au incorporation at the interface; glancing angle deposition and electron beam evaporation followed by annealing. Unlike the glancing angle deposited Au film, the larger Au nanoparticles(NPs) formed by electron beam evaporation and annealing, and when embedded at SnO2/NiO interface, generated 9.6 µA of photocurrent and dark currents were lowered by one order. The modified diode characteristics were studied using impedance spectroscopy. The junction capacitance and time constant of Au incorporated devices were found to be much lower than that of bare SnO2/NiO heterojunction, leading to an improved response time and SPD performance. The responsivity, rise time, detectivity, and ON/Off ratio calculated for the device SnO2/NiO with Au NPs at the interface were 3.1 mA W−1, 1.6 s, 1.8 × 1010 Jones, and 2.6 × 103 respectively, best among all the devices. The heterojunction PDs with Au incorporation are a potential way to address the surface and interface effects at the nanoscale, thereby improving the device performance.

2D flakes of Au decorated SnO2 nanoparticles as electrode material for high performing supercapacitor

2D decorated nanostructures are fast emerging as efficient electrode materials for electrochemical devices. Au decorated SnO2, synthesized using co-precipitation and hydrothermal methods, can become a useful electrode material for supercapacitors. Au incorporation helps to mitigate the conductivity issues of SnO2 nanostructures. The superior 2D-flake like morphology leads to appreciable performance enhancement, with specific capacitance of 234 F g−1 at 1 A g−1 current density, which is much larger than that observed in pristine SnO2. The high cycling stability of Au-decorated SnO2 clearly shows its usefulness for high-performance supercapacitors. A theoretical model is also reported to explain the electrochemical results.

Noble metals (Pd, Ag, Pt, and Au) doped bismuth oxybromide photocatalysts for improved visible light-driven catalytic activity for the degradation of phenol

The doping of noble metals onto the semiconductor metal oxides has a great impact on the intrinsic properties of the materials. This present work reports the synthesis of noble metals doped BiOBr microsphere by a solvothermal method. The various characteristic findings reveal the effective incorporation of Pd, Ag, Pt, and Au onto the BiOBr and the performance of synthesized samples was test for the degradation of phenol over visible light. The Pd-doped BiOBr material showed enhanced phenol degradation efficacy, which is ∼4-fold greater than pure BiOBr. This improved activity was on reason of good photon absorption, lower recombination rate, and higher surface area facilitated by surface plasmon resonance. Moreover, Pd-doped BiOBr sample displayed good reusability and stability after 3 cycles of run. A plausible charge transfer mechanism for phenol degradation is disclosed in detail over Pd-doped BiOBr sample. Our findings disclose that the incorporation of noble metal as the electron trap is a feasible approach to enhance visible light activity of BiOBr photocatalyst used in phenol degradation. This work represents new vision interested in the outline and development of noble metal doped semiconductor metal oxides as a visible light material for the elimination of colorless toxins from untreated wastewater.

Heterojunction nanoarchitectonics of WOx/Au-g-C3N4 with efficient photogenerated carrier separation and transfer toward improved NO and benzene conversion

Topics on effectively improving the photochemical CO2/benzene/NO oxidation conversion performances of g-C3N4 based materials via charge transfer and separation enhancement are still considered challenging, despite the growing popularity of applying these materials in a variety of energy conversion related applications. Based on the idea of nanoarchitectonics, a post-nanotechnology concept, WOx/Au-g-C3N4 heterostructures are synthesized using two-step thermal polymerization and solvothermal treatment methods in this paper. Small Au nanoparticles are incorporated in superior thin g-C3N4 via mechano-chemical pre-reaction and two-step thermal polymerization (treated at 500 and 700 °C). Enhanced photocurrent density is observed after incorporation of Au, which is also in good agreement with the photocatalytic activity (H2 generation and CO2 reduction) data. Layered WOx with abundant oxygen vacancies are further incorporated into Au-modified g-C3N4 nanosheets to form heterojunctions possessing excellent photocatalytic CO2 photo-reduction performances with CO and CH4 generation rate of 5.64 and 2.58 μmolg−1h−1, respectively, under full solar spectrum. The heterojunctions constructed via in-situ formation show direct Z-scheme charge transfer pathway with improved charge separation and transport efficiencies. These highly stable and recyclable hierarchical g-C3N4 hybrid nanostructures (WOx/Au-g-C3N4 heterojunctions) show outstanding conversion rate (88.1%) and selectivity (99.3%) for benzene to phenol conversion under full solar spectrum condition, as well as excellent NO removal rate (61%).

Redox-Guided Synthesis of Au–V2O5–MnO2 Nanoflower Composites with Enhanced Electrical Conductance for Supercapacitor Applications

This paper details an approach for the synthesis of stable electroactive Au–V2O5–MnO2 nanoflower composites using a simple redox-mediated methodology under modified hydrothermal (MHT) conditions. The nanocomposite was characterized by various techniques like X-ray diffraction, scanning electron microscopy, high-resolution transmisson electron microscopy, and X-ray photoelectron spectroscopy. MnO2 and Au formed a profitable hierarchical network morphology in the interstitial sites of V2O5, and this kind of synergetic architecture exhibits an elevated specific capacitance (388 F g–1 at 1 A g–1) compared to commercial V2O5 (85 F g–1 at 1 A g–1) in a neutral electrolyte. The as-synthesized nanocomposite contributed more to energy storage with superior energy density (49 Wh kg–1 at 1 A g–1 current density) and power density (4 kW kg–1 at 10 A g–1 current density) and demonstrated improved stability compared to commercial V2O5 of up to 2000 continuous charge/discharge cycles in a two-electrode system. Temperature- and field-dependent [both direct-current (dc) and alternating-current (ac)] studies exhibited enhanced conductance due to the incorporation of Au and MnO2 and non-Ohmic electrical conduction, characterized by the onset voltage V0 (dc) and onset frequency f0 (ac). These two onset parameters followed power-law behavior with Ohmic conductance with two onset exponents (xV and xf). Such electrical transport properties were explained using intrachain hopping conduction of charge carriers within the layers of pristine V2O5 and hopping of charge carriers between the layers of V2O5 in the Au–V2O5–MnO2 nanocomposite and supported the interstitial incorporation of the compounds.

Thermal, dielectric and optical studies on cellulose acetate butyrate-gold nanocomposite films prepared by laser ablation

This work employed pulsed laser ablation to produce cellulose acetate butyrate-gold (CAB-Au) nanocomposite films and the evaluation of their structural and thermal characteristics using Raman, X-ray diffraction (XRD), thermogravimetric analysis (TGA), and Differential Scanning Calorimetry (DSC). In the frequency range 0.1–10 MHz, nanocomposite films' dielectric constant, loss, and electric modulus behavior were investigated as a function of temperature. The refractive index, finesse coefficient, Brewster coefficient, critical angles, dielectric function, and color properties of nanocomposite films were examined in the wavelength range 190–800 nm. X-ray diffraction shows a strong Au diffraction signal in all samples, confirming Au NPs. The SEM micrograph shows Au embedded in CAB. The CAB-Au nanocomposites had higher thermal stabilities (Tm) than pure CAB, and the DSC thermograms showed a fluctuating glass transition temperature due to the dynamics of organic-inorganic interactions in the nanocomposite films. Dielectric dispersion is caused by hidden dipolar polarization. The CAB (5 min) sample had the highest ac conductivity as a function of frequency at various temperatures as the Au content in the Au/CAB composite rose. The simplest quantum mechanical tunneling (QMT) model also best explains the ac conduction property. We found a relationship between the nanocomposites' refractive index and the amount (extent of incorporation) of Au in the materials, with laser irradiation time determining the various color constants. Tauc plots reveal a permitted transition with an optical energy gap of 5.1eV for the polymer film and 4.75eV after 10 and 20 min of laser irradiation.

A comparative study of palladium-gold and palladium-tin catalysts in the direct synthesis of H2O2

Supported PdSn catalysts are highly effective for the direct synthesis of hydrogen peroxide showing significantly higher selectivity to comparable PdAu catalysts.

Fabrication of bimetallic inlaid working electrode for highly efficient dye sensitized solar cells

Gold nanoparticles (AuNPs) including Au-Pink, Au-Orange, Au-Purple, Au-Blue were synthesized using chemical reduction method, their optical and morphological properties were characterized and they were used in PV devices. The active layer of dye-sensitized solar cells having titanium dioxide (TiO2) solid microsphere (MS) made up of nanoparticles granules were coated with AuNPs. This Au-TiO2 MS hybrid DSSC boosted light harvesting, charge separation, and improved the charge transportresulting in an improvement of both short circuit current and open circuit voltage. The power conversion was boosted 16% compared to the control photoanode of TiO2 solid microsphere. Further enhancement in the short circuit current was observed during the incorporation of both Au and Ag, bi-metallic nanoparticles in the TiO2 matrix. An overall photo to electron conversion efficiency of 8.73% was obtained due to the plasmonic cooperation effect of TiO2-Ag-Au hybrid structures, which is 65% increase over pure TiO2 DSSCs. The local electrified intensity enhancement around the individual Ag, Au nanoparticles and plasmonic coupling of the Ag-Au combination have been used to explain these results with finite-difference time-domain simulation.

Embedded gold nanoparticles in TiO2 crystal for photonic applications

• Plasmonic Au nanoparticles are synthesized in TiO 2 crystal by ion implantation. • Third-order optical nonlinearity tailoring is achieved through charge transfer between Au nanoparticles and TiO 2 . • Enhanced modulation depth and optimized saturation intensity suggest significant potential photonic applications. Gold nanoparticles (Au NPs) are synthesized inside TiO 2 crystal by Au + ion implantation. The incorporation of Au + ions in TiO 2 brings out the modification of optical features of the bulk due to the localized surface plasmon resonance (LSPR) effect. The linear absorption spectra of Au NPs dispersed in TiO 2 crystal possesses an absorption peak at 638 nm. The third order optical nonlinearities of TiO 2 with Au NPs are modulated with reduced saturation intensity and increased modulation depth, compared with pure TiO 2 bulk. Our results pave a way to use TiO 2 with embedded Au NPs for nonlinear photonic applications.

Hybrid Enzymatic/Photocatalytic Degradation of Antibiotics via Morphologically Programmable Light-Driven ZnO Microrobots.

Antibiotics are antimicrobial substances that can be used for preventive and therapeutic purposes in humans and animals. Their overdose usage has led to uncontrolled release to the environment, contributing significantly to the development of antimicrobial resistance phenomena. Here, enzyme-immobilized self-propelled zinc oxide (ZnO) microrobots are proposed to effectively target and degrade the released antibiotics in water bodies. Specifically, the morphology of the microrobots is tailored via the incorporation of Au during the synthetic process to lead the light-controlled motion into having on/off switching abilities. The microrobots are further modified with laccase enzyme by physical adsorption, and the immobilization process is confirmed by enzymatic activity measurements. Oxytetracycline (OTC) is used as a model of veterinary antibiotics to investigate the enzyme-immobilized microrobots for their removal capacities. The results demonstrate that the presence of laccase on the microrobot surfaces can enhance the removal of antibiotics via oxidation. This concept for immobilizing enzymes on self-propelled light-driven microrobots leads to the effective removal of the released antibiotics from water bodies with an environmentally friendly strategy.

Age and mineralization processes of decratonic lode gold deposits in the southern North China Craton: Constraints from trace elements, in-situ S-Pb isotopes and Rb-Sr geochronology of pyrite from the Chen’er gold deposit

The Chen’er gold deposit, with 27 tons of known Au reserves, is one of the typical gold deposits in the Xiaoqinling district along the southern part of the North China Craton. In order to better understand the gold precipitation time and mineralization process, we report in-situ Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) trace element analyses, elemental maps, and the Rb-Sr and S-Pb isotopic composition of sulfides from the Chen’er gold deposit with a view to gain insights into the mineralization time and process. Trace element analyses and elemental maps of pyrite show that the content of As is low and has no correlation with Au, indicating As is unlikely to have controlled the Au incorporation into pyrite. Gold mainly occurs as solid solutions in the Py Ⅰ and Py Ⅱ, and as Au-Ag and/or Au-Te sub-micrometer inclusions in Py III. The Rb-Sr isotopic data on sulfides from the Chen’er deposit yielded an isochron age of 129.2 ± 3.4 Ma, which overlaps with the previously reported 40Ar/39Ar age of hydrothermal mica, indicating that the gold mineralization occurred in the Early Cretaceous. The in-situ sulfur isotope values of sulfides from stage Ⅱ to stage III fluctuate significantly (the average value decreases from 4.95 to −0.24‰) and were affected by physicochemical parameters of the mineralization process, especially ƒO2. In addition, the δ34S values are in a narrow range (-1.34 to 5.24‰), indicating a magmatic source for the sulfur. In-situ Pb isotopic compositions of the pyrite and galena of stage Ⅱ and stage III are relatively constant with 208Pb/204Pb, 207Pb/204Pb, and 206Pb/204Pb values in the range of 37.264–37.595, 15.364–15.423, 16.992–17.078, respectively, indicating a mixed mantle-crust origin. Based on the new geochronological, geochemical and isotopic data presented in this study, and combined with those from previous studies, we suggest that the lode gold deposits in the Xiaoqinling district are magmatic hydrothermal ore deposits, with metal and ore-forming fluid originating primarily from the mantle, coupled with the cratonic reactivation during the Early Cretaceous.

Gold-modified ZnO nanocomposites for photo-Fenton-like catalysis of Escherichia coli disinfection

In this study, gold-modified zinc oxide (Au/ZnO) nanocomposites were fabricated using the solvothermal method. Structure, morphology, and components of Au/ZnO nanomaterials were investigated by XRD, TEM, and XPS analyses, respectively. Results of the UV–Vis analysis manifested a shifting of absorption to light of nanocomposites from visible towards red because of the incorporation of Au and its surface plasmon resonance. In addition, an antibacterial test demonstrated that as compared to pure ZnO and ZnO nanocomposites cooperated with other contents of Au, 1/101 Au/ZnO nanocomposites displayed the highest photocatalysis disinfection activity to Escherichia coli cells. Fenton-like and photo-Fenton-like reactions were executed to further explore the effect of 1/101 Au/ZnO nanocomposites, in which the ESR results revealed the producing of hydroxyl radicals that are considered as one of the dominants to antibacterial activity during photocatalytic disinfection process.