Mixed Au Research Articles

Infrared spectra and fragmentation dynamics of isotopologue-selective mixed-ligand complexes.

Isolated mixed-ligand complexes provide tractable model systems in which to study competitive and cooperative binding effects as well as controlled energy flow. Here, we report spectroscopic and isotopologue-selective infrared photofragmentation dynamics of mixed gas-phase Au(12/13CO)n(N2O)m+ complexes. The rich infrared action spectra, which are reproduced well using simulations of calculated lowest energy structures, clarify previous ambiguities in the assignment of vibrational bands, especially accidental coincidence of CO and N2O bands. The fragmentation dynamics exhibit the same unexpected behaviour as reported previously in which, once CO loss channels are energetically accessible, these dominate the fragmentation branching ratios, despite the much lower binding energy of N2O. We have investigated the dynamics computationally by considering anharmonic couplings between a relevant subset of normal modes involving both ligand stretch and intermolecular modes. Discrepancies between correlated and uncorrelated model fit to the ab initio potential energy curves are quantified using a Boltzmann sampled root mean squared deviation providing insight into efficiency of vibrational energy transfer between high frequency ligand stretches and the softer intermolecular modes which break during fragmentation.

Sol-Gel Synthesis of Uniform Arrays of Ag and Au Nanoparticles

The obtaining of uniform arrays of silver and gold nanoparticles with a surface density up to 3.3∙109 cm–2 on the zinc oxide buffer layers by sol-gel method is described. The variations of the solution composition and synthesis mode, layers coating and subsequent heat treatment were carried out. The absorption spectra of the obtained samples had a peak near 400–570 nm corresponding to the plasmon resonance in the Ag and Au nanoparticles. Wavelength and shape of Ag and Au nanoparticles plasmon peak varied depending on the synthesis mode: the use of ZnO buffer layers leads to an increase in the intensity of the nanoparticles plasmon peak, the annealing leads to a gradual decrease and broadening of the absorption peak of Ag and mixed Ag and Au nanoparticles arrays, but does not affect the peak of Au nanoparticles.

Experimental and computational insights into luminescence in atomically precise bimetallic Au6-nCun(MPA)5 (n = 0-2) clusters.

Bimetallic nanoclusters (NCs) have emerged as a new class of luminescent materials for potential applications in sensing, bio-imaging, and light-emitting diodes (LEDs). Here, we have synthesized gold-copper bimetallic nanoclusters (AuCu NCs) using a one-step co-reduction method and tuned the emission wavelength from 520 nm to 620 nm by changing the [Cu2+]/[Au3+] molar ratio. The quantum yield (QY) increases from 6% to 13% upon incorporation of the Cu atom in the Au NCs. MALDI-TOF mass spectrometric analysis reveals that the composition of the Au NCs is Au6(MPA)5, and the bimetallic nanocluster is Au4Cu2(MPA)5, where 3-mercaptopropionic acid (MPA) is used as the capping ligand. Furthermore, we investigated the optimized structures of the as-synthesized NCs using density functional theory (DFT) along with analysis of the preferable adsorption sites using Fukui functions. We report the HOMO-LUMO gap, which is consistent with the experimentally observed red shift in the UV-Vis absorption features of the Au NCs upon copper doping. XPS studies suggest the formation of intermixing of states between the 5d orbitals of Au and the 3d orbitals of Cu in the AuCu NCs after incorporating Cu atoms into the Au NCs, which is corroborated by the DFT calculations on electronic charge transfer from the Cu to the Au atom in the NCs. The coupling between Au(I) and Cu(I) facilitates the formation of a low-lying mixed Au(I)-Cu(I) energy state. This study elaborates on the impact of Cu doping on the excited-state relaxation dynamics of AuCu NCs.

Heterostructured Au–Ir Catalysts for Enhanced Oxygen Evolution Reaction

Electrochemical water splitting operated under acidic conditions provides a clean approach to generate hydrogen fuels. Currently, the sluggish kinetics of oxygen evolution reaction (OER) at the anode is a bottleneck limiting the acidic water splitting. Here, we report that the OER activity of Ir, one of the most commonly used OER catalysts, can be boosted by forming phase boundaries with Au. Mixed Au and Ir catalysts were synthesized on carbon paper electrodes, which underwent structural evolution under the OER environment to form an Au-Ir interface-rich structure. Compared with Ir catalyst, which requires an overpotential of ∼393 mV to achieve a current density of 10 mA/cm2 in 0.1 M HClO4 electrolyte, the evolved Au-Ir catalyst shows a lower overpotential at ∼351 mV. X-ray photoelectronic spectrum (XPS) study, in conjunction with electrochemical analysis on the surface-site-normalized activity, reveals that the improved OER performance is due to the presence of Au/Ir interfaces in the catalysts. In addition to Ir, the strategy of accelerating OER via Au/Ir interfaces has been further applied to IrCo, IrNi, and IrCu alloy catalysts. With the broad applicability of the strategy demonstrated, this study opens a new route to design OER catalysts for efficient acidic water splitting.

Effect of external electric field on the formation of colloidal Ag–Au alloy nanoparticles through laser post-irradiation

We report the synthesis of Ag–Au alloy nanoparticles (NPs) by post-irradiation of mixed colloidal Ag and Au NPs by a nanosecond pulse laser in the presence of an external electric field (EEF). In our study, size, optical, and plasmonic properties of colloidal Ag–Au alloy NPs were investigated. A colloid of individual Ag and Au NPs were separately prepared by nanosecond pulsed laser ablation in distilled water. An appropriate volume of these colloidal NPs samples was mixed and post-irradiated with the same pulsed laser beam in the presence of a uniform electric field, resulting in the formation of Ag–Au alloy NPs. The synthesized colloidal alloy NPs were characterized using scanning electron microscopy and UV–vis absorption spectroscopy. The results indicate that the EEF can reduce significantly the Ag–Au alloy formation time. The results also show that the wavelength of the localized surface plasmon resonance of alloy NPs decreased by the applied electric field.

Computational Characterization of the Intermixing of Iron Triade (Fe, Co, and Ni) Surfaces and Sub-nanometric Clusters with Atomic Gold.

Dispersion-corrected density functional theory (DFT-D3) is applied to model iron triade (Fe, Co, and Ni) surfaces upon exchange of surface atoms with atomic gold. One first goal is to analyze the contact problem at the triade surface–Au interface and to correlate our findings with recent observations on iron triade nanoparticles (with diameters of around 5 nm) passivated by a few layers of gold. For this purpose, we analyze: (1) the energies of substitution; (2) the restructuring of the iron triade surfaces upon the atomic exchange; (3) the density of the orbitals bearing the largest projection on d(Au) atomic orbitals and, particularly, their overlap with orbitals from neighboring atoms of the triade surfaces; (4) the modification of the electronic density of states; and (5) the redistribution of the electronic density upon intermixing of Au and triade atoms. Inspite of the similarities between Ni, Co, and Fe in the condensed phase, significant differences are found in the features characterizing the exchange process. In particular, we find a better integration of the Au atom on the substitutional site of the Ni(001) surface than on those of the Fe(001) and Co(001) surfaces. This is in agreement with the fact that the electronic density of states is almost indistinguishable before and after Ni–Au intermixing. This outcome is correlated with the experimental observation on the allowing transition of Ni–Au core–shell nanoparticles before reaching the melting temperature. Our second objective is to explore the Au–triade atom intermixing process in sub-nanometric clusters, finding that it is energetically more favored than at solid surfaces yet endothermic at 0 K. This feature is explained as the result of the structural fluxionality characterizing clusters at the sub-nanometer scale. Entropy contributions make mixed Au–Ni clusters more stable than the unmixed counterpart already at 650 K while unmixed Co clusters remain energetically more favored up to 1295 K and iron clusters are predicted to be stable against intermixing over the experimentally relevant range of temperatures (up to 1100 °C). Remarkably, the net charge donated from the three triade atoms to atomic gold upon intermixing is similar in triade sub-nanometeric clusters and at extended triade surfaces. Gold clusters are prone to host Fe, Co, and Ni atoms at the center of their structures and the exchange process is predicted to be exothermic at 0 K even for a small cluster made of 13 atoms. More generally, our work highlights the importance of the polarity of the chemical bond between unlike metal atoms in alloys.

Regeneration of Reactive Pd Surfaces in Au-Pd Nanoparticles after Electrochemical Aging

One major hurdle in the development of efficient electrocatalysts is deterioration of activity, which can be caused by selective dissolution of metals [1]. The recent development of gold-palladium (Au-Pd) alloy nanoparticles outlines a contemporary strategy to impart increased stability in nanoparticles by combining a more electrochemically stable metal such as Au with lesser stable Pd [2, 3]. Unfortunately, the relative surface-reactivity of Au is poor, and as a result, there is an inevitable design constraint to form Pd-rich outer shell structure - a task that is particularly daunting considering the high dissolution tendency of Pd [4]. Here we present an electrochemical aging method that allows for increasing the Pd concentration at the surface of Au-Pd NPs by means of diffusion of Pd atoms from the particle-core to the shell. The method involves an electrochemical aging treatment in alkaline KOH media for which the choice of suitable upper vertex potential proved to be particularly very important.Au-Pd NPs synthesized by means of liquid-phase laser-ablation method [5] were used in this study, typically ranging in diameter between 14.5 nm to 22.6 nm and composition between Au/Pd: 20/80 to 80/20 ratios. The particle diameter remained homogeneous across the whole composition range, thanks to the size-selectivity of laser-ablation synthesis of alloy molar fraction series, in line with the literature [5]. This allows for excluding any size-effects on the electrochemical behaviour of alloy nanoparticles. The nominal Au/Pd compositions initially fed to the laser appeared to be well preserved down to single-nanoparticle level as confirmed by detailed analyses of the SEM/EDX and XPS spectroscopic data. Formation of Au/Pd solid-solution was also apparent from the estimation of the lattice-parameters using X-ray diffraction (XRD) that varied linearly in accordance with the change in Pd alloy content.The cyclic voltammograms recorded in 0.1M N2-saturated KOH revealed features characteristic of both Au and Pd surfaces, e.g., the reduction peaks at 0.98 V and 0.55 V vs RHE (respectively), which was reflective of a mixed Au and Pd surface-structure exposed to the electrochemical treatments. Importantly, both the peak-positions and the integrated surface-charge shifted in correspondence with the variable Pd content in the alloys, thus serving as the initial markers of the surface-state before further electrochemical treatments.Marked differences could be noted between the electrochemical behaviours in acid and the alkaline media, as well as the potential range and the number of cycles involved ( Figure 1 ). The initial H-desorption/adsorption peaks (A, B) and the PdO reduction peaks apparent at the onset of aging in 0.5M H2SO4 gradually disappeared with subsequent cycling (C1), along with the concomitant rise in the Au oxide reduction peaks (D1), indicative of gradually dissolution of Pd. Importantly, the lost Pd surface surprisingly regenerated (C2) with subsequent aging in 0.1M KOH media, particularly at sweeping potentials extending to very positive values. The regenerated Pd-rich surface is attributed to preferential diffusion of Pd from particle cores- to the surface aided by surface-reconstruction via a ‘place-exchange’ between adsorbed-oxygen and Pd. Detailed analyses of the XPS Pd-3d3/2 and Au-4f7/2 edges and the respective STEM-EDX elemental profiles are in good agreement with the changes of surface-structures proposed from the cyclic voltammetry measurements. All the alloys were simultaneously tested for oxygen reduction reaction (ORR).[1] Gasteiger, H. A., et al. (2005). Applied Catalysis B: Environmental, 56(1-2), 9-35.[2] Xu, J. B., et al. (2010). International Journal of Hydrogen Energy, 35(13), 6490-6500.[3] Sasaki, K., et al. (2010). Angewandte Chemie International Edition, 49(46), 8602-8607.[4] Rand, D. A. J., et al. (1972). Journal of Electroanalytical Chemistry and Interfacial Electrochemistry, 35(1), 209-218.[5] Reichenberger, S., et al. (2019). ChemCatChem, 11, 4489-4518. Figure 1

Electrooxidation of Glycerol on Self-Organized, Mixed Au–Pt Interfaces Formed on Ni Substrates

Glycerol is a biproduct of esterification reactions in biodiesel production. Identifying new uses for the significant oversupply of glycerol can reduce the costs associated with biodiesel production. Glycerol is of interest as the anodic half-reaction paired with cathodic electrolytic reactions such as hydrogen evolution or CO2 reduction. Replacing water oxidation with glycerol oxidation can significantly decrease the overall cell potential for generating the reduced product on the cathode, and thus, improve the power conversion efficiency of the cathodic process. Here, we describe a method for fabricating hierarchically-structured glycerol electrooxidation anodes by galvanic replacement reactions on Ni substrates. We show that galvanic replacement is an effective approach to synthesize mixed Au–Pt electrodes with improved electrochemical durability and lower onset potentials for glycerol oxidation compared to otherwise identical monometallic Pt or Au electrodes, respectively. X-ray photoelectron spectroscopy characterization of the mixed-metal electrodes show that the electronic structure of surface Pt is modified by the presence of Au, which can possibly explain the enhanced electrochemical durability of the mixed-metal electrodes. We also show that the galvanic replacement process can be translated to high surface area Ni foam electrodes for improving the electrochemical durability at higher geometric current densities vs equivalent planar electrodes.

Selective Oxidation of Glycerol to Dihydroxyacetone over Au/CuxZr1-xOy Catalysts in Base-Free Conditions.

In this paper, a series of Cu-Zr mixed metal oxide-supported Au catalysts were prepared by deposition-precipitation and evaluated for selective oxidation of glycerol to dihydroxyacetone (DHA) in base-free conditions. The best catalytic performance was obtained with DHA selectivity of up to 95% and yield of 70% in 4 h, 50 °C and PO2 = 0.2 MPa over the Au/Cu0.95Zr0.05 and Au/Cu0.9Zr0.1 catalysts. Combined with the characterization results of Brunauer-Emmett-Teller, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and CO2 temperature programmed desorption, it was proposed that the content of Au0, the size of Au, and the basicity of the catalyst affected the glycerol conversion and DHA selectivity. After the catalyst was recycled four times, the glycerol conversion decreased by about 14% which might result from the carbon deposition or the byproduct adsorption and the agglomeration of Au particle.

Conjugating gold nanoclusters and antimicrobial peptides: From aggregation-induced emission to antibacterial synergy

Antimicrobial peptides and antibacterial nanostructures are two emerging classes of antimicrobial agents that differ from conventional small-molecule antibiotics. Combining these two types of antimicrobial agents into one entity may be an effective strategy to improve their antimicrobial efficiency. In this study, we demonstrated an effective antibacterial hybrid formed by covalently conjugating antibacterial gold nanoclusters (Au NCs, a novel antimicrobial nanostructure) and daptomycin (Dap, a cyclic lipopeptide antimicrobial peptide). The as-synthesized hybrid structure (Dap−Au NCs) not only inherits the intrinsic properties from both agents but also renders an enhanced synergistic effect. Compared with the physically mixed Au NCs and daptomycin (Dap+Au NCs), the Dap−Au NCs hybrid structure has a stronger bactericidal effect toward methicillin-resistant Staphylococcus aureus, a representative of multidrug-resistant bacteria. Dap−Au NCs could effectively disrupt bacterial membranes by creating more and/or larger holes in the membranes due to the localized daptomycin within the conjugated structure. These larger (and possibly more) holes motivate the entry of Dap−Au NCs into bacterial cells and lead to more serious damage of the bacteria at subcellular levels. Moreover, bacterial genomic DNA fragmentation was further quantified to show that Dap−Au NCs may induce severe DNA breaks. The strong DNA destruction benefited from localized high concentrations of reactive oxygen species (ROS) induced by the localization of Au NCs in the antimicrobial conjugation. The conjugated Au NCs could serve as a critical free radical generator to continuously produce ROS within the bacteria. The continuous ROS bombings also limit the capacity of the bacteria to develop drug resistance. In addition, a significant fluorescence enhancement of the hybrid structure was observed due to a novel aggregation-induced emission (AIE) pattern caused by the Au NCs and daptomycin conjugation. This conjugation strategy provides a new perspective for the synthesis of new antimicrobial agents as well as AIE-type fluorescence materials.

A Computational and Experimental Investigation of the Phonon and Optical Properties of Au₂P₃.

In a combined experimental and theoretical study of gold phosphide (Au2P3), we investigate its vibrational properties, band structure, and dielectric properties, providing new insight into the properties of this underexplored material. Using a simple synthesis route, Au2P3 thin films were produced, enabling the first reported Raman analysis of this material. Coupled with first-principles calculations of these Raman modes, this analysis reveals that low-frequency vibrations are due to Au or mixed Au to P, and at higher frequencies, they are due to P vibrations. Further band structure and dielectric calculations reveal Au2P3 to be a narrow band (0.16 eV) indirect semiconductor. This work helps to fill major gaps in our understanding of key properties in this material that will benefit future research in this field.

High Performance Silicon/Organic Hybrid Solar Cells with Dual Localized Surface Plasmonic Effects of Ag and Au Nanoparticles

Effective light trapping induced by a dual localized plasmonic effect of Au and Ag nanoparticles (NPs) is adopted in poly‐(3,4‐ethylenedioxythiophene):poly (styrenesulfonic acid) (PEDOT:PSS) hybrid solar cells. Superior performance on light absorption is obtained after incorporating mixed Au and Ag NPs incorporating into PEDOT:PSS layer. Compared to devices with single NPs that only shows very limited plasmonic enhancement, dual NPs doped devices benefit from the dual plasmonic enhancement in visible light region. Therefore, power conversion efficiency (PCE) of 11.98 % has been achieved, which is about 18% higher than that of with the pristine one, exhibiting a PCE of 9.72%. The PCE enhancement is largely ascribed to the short‐circuit current (JSC) enhancement, which can be observed through the external quantum efficiency (EQE) curves. In addition, transient photovoltage (TPV) results show that the charge carrier lifetime is improved by the incorporation of dual nanoparticles, indicating a suppressed charge recombination during the physical process in the devices.

Bioselective synthesis of gold nanoparticles from diluted mixed Au, Ir, and Rh ion solution by Anabaena cylindrica

Over the last years, an environmentally friendly and economically efficient way of nanoparticle production has been found in the biosynthesis of metal nanoparticles by bacteria and cyanobacteria. In this study, Anabaena cylindrica, a non-toxic cyanobacterium, is deployed in a diluted ionic aqueous mixture of equal concentrations of gold, iridium, and rhodium, of 0.1 mM each, for the selective biosynthesis of metal nanoparticles (NPs). To analyze the cyanobacterial metal uptake, X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and inductively coupled plasma mass spectrometry (ICP-MS) were applied. Only gold can be found in crystalline and nanoparticle form inside the cells of A. cylindrica, and it is the only metal for which ICP-MS analyses show a rapid decrease of the concentration in the culture medium. A slight decrease of rhodium and none of iridium was observed in the evaluated timeline of 51 h. The average diameter size of the emerging gold nanoparticles increased over the first few days, but is found to be below 10 nm even after more than 2 days. A new evaluation method was used to determine the spatially resolved distribution of the nanoparticles inside the cyanobacterial cells. This new method was also used to analyze TEM images from earlier studies of A. cylindrica and Anabaena sp., both incubated with an overall concentration of 0.8 mM Au3+ to compare the metal uptake. A. cylindrica was found to be highly selective towards the formation of gold nanoparticles in the presence of rhodium and iridium.

Hemin/Au nanorods/self-doped TiO2 nanowires as a novel photoelectrochemical bioanalysis platform.

As a recently developed detection technique, photoelectrochemical (PEC) measurement has received extensive attention. However, owing to the lack of a comprehensive approach to engineer the photo-generated carriers, the performance is still limited. As an example, a significant use of PEC measurement might be in understanding the roles of glutathione in physiological and pathological processes. Here, we developed a new approach for engineering the photo-generated carriers with the aid of the synergic effect of self-doping, surface plasmon resonance, electrical field amplification effect, etc. Thus, a highly sensitive multicomponent PEC platform has been developed, in which Au nanorods are decorated on the surface of self-doped TiO2 nanowires, followed by surface receptor functionalization with hemin for capturing glutathione. The synergic effect effectively increases generation, separation and transfer kinetics of the photo-generated carriers, which can be further increased by using a mixture of Au nanorods with different aspect ratios to tune the absorption wavelength to the entire UV-visible region. As a result, this system exhibits a broad linear range from 10 nM to 17.5 μM and low detection limit down to 8.6 nM for detecting glutathione, about 1-2 orders of magnitude lower than most existing PEC sensors.

Opportunities and challenges in the electrocatalysis of CO2 and CO reduction using bifunctional surfaces: A theoretical and experimental study of Au–Cd alloys

Electrolysis could enable the large-scale conversion of CO2 to fuels and small molecules. This perspective discusses the state-of-the-art understanding of CO2 and CO reduction electrocatalysis and provides an overview of the most promising approaches undertaken thus far. We set to explore “bifunctional” catalysts using Au–Cd based alloys inspired by theoretical modelling. Density functional theory calculations suggest more favourable thermodynamics for CO2 reduction to CO and methanol on mixed Au–Cd sites on Au3Cd relative to similar values on Au. We use various tools to test the bulk and surface alloys experimentally. We find that Au3Cd in neutral media exhibits lower CO evolution activity than Au, and Au–Cd alloys also show negligible activity for CO reduction in alkaline media. This indicates that the mixed Cd–Au sites predicted to be catalytically active are not present in the sample. The catalytic performance is most consistent with Au-terminated step surface on a bulk alloy, possibly formed through adsorbate-induced restructuring. We highlight that future bimetallic catalysts must consider potential-dependent surface restructuring effects caused by reaction intermediates.

Molecular Gold Wire from Mixed-Valent Au(I/III) Complexes.

Crystals of mixed-valent Au complexes have been grown from solutions of cyclohexanecarbonitrile and a stoichiometric amount of gold(I) and gold(III) chloride. The purely obtained compound was characterized as bis(cyclohexanecarbonitrile)gold(I) tetrachloridoaurate(III). The crystal packing of the mixed valent Au(I/III) compound demonstrates a columnar arrangement of the gold(I) and gold(III) atoms. The new structure displays the shortest unsupported gold(I)-gold(III) interactions with the sub-van der Waals distance of 324-325 pm, which is assumed as an aurophilic bonding interaction.

Probing the structures of gold-aluminum alloy clusters AuxAly(-): a joint experimental and theoretical study.

Besides the size and structure, compositions can also dramatically affect the properties of alloy nanoclusters. Due to the added degrees of freedom, determination of the global minimum structures for multi-component nanoclusters poses even greater challenges, both experimentally and theoretically. Here we report a systematic and joint experimental/theoretical study of a series of gold-aluminum alloy clusters, AuxAly(-) (x + y = 7,8), with various compositions (x = 1-3; y = 4-7). Well-resolved photoelectron spectra have been obtained for these clusters at different photon energies. Basin-hopping global searches, coupled with density functional theory calculations, are used to identify low-lying structures of the bimetallic clusters. By comparing computed electronic densities of states of the low-lying isomers with the experimental photoelectron spectra, the global minima are determined. It is found that for y ≥ 6 there is a strong tendency to form the magic-number square bi-pyramid motif of Al6(-) in the AuxAly(-) clusters, suggesting that the Al-Al interaction dominates the Au-Au interaction in the mixed clusters. A closely related trend is that for x > 1, the gold atoms tend to be separated by Al atoms unless only the magic-number Al6(-) square bi-pyramid motif is present, suggesting that in the small-sized mixed clusters, Al and Au components do not completely mix with one another. Overall, the Al component appears to play a more dominant role due to the high robustness of the magic-number Al6(-) square bi-pyramid motif, whereas the Au component tends to be either "adsorbed" onto the Al6(-) square bi-pyramid motif if y ≥ 6, or stays away from one another if x < y < 6.

Nanoscale Au–In Alloy–Oxide Core–Shell Particles as Electrocatalysts for Efficient Hydroquinone Detection

The presence of hydroquinone (HQ), a phenol ubiquitous in nature and widely used in industry, needs to be monitored because of its toxicity to the environment. Here we demonstrate efficient detection of HQ using simple, fast, and noninvasive electrochemical measurements on indium tin oxide (ITO) electrodes modified with nanoparticles comprising bimetallic Au–In cores and mixed Au–In oxide shells. Whereas bare ITO electrodes show very low activity for the detection of HQ, their modification with Au–In core–shell nanoparticles induces a pronounced shift of the oxidation peak to lower potentials, i.e., facilitated oxidation. The response of the different electrodes was correlated with the initial composition of the bimetallic nanoparticle cores, which in turn determined the amount of Au and In stabilized on the surface of the amorphous Au–In oxide shells available for the electrochemical reaction. While adding core–shell nanostructures with different compositions of the alloy core facilitates the electrocata...

A Novel Designed Bioreactor for Recovering Precious Metals from Waste Printed Circuit Boards.

For recovering precious metals from waste printed circuit boards (PCBs), a novel hybrid technology including physical and biological methods was developed. It consisted of crushing, corona-electrostatic separation, and bioleaching. Bioleaching process is the focus of this paper. A novel bioreactor for bioleaching was designed. Bioleaching was carried out using Pseudomonas chlororaphis. Bioleaching experiments using mixed particles of Au and Cu were performed and leachate contained 0.006 mg/L, 2823 mg/L Au+ and Cu2+ respectively. It showed when Cu existed, the concentrations of Au were extremely small. This provided the feasibility to separate Cu from Au. The method of orthogonal experimental design was employed in the simulation bioleaching experiments. Experimental results showed the optimized parameters for separating Cu from Au particles were pH 7.0, temperature 22.5 °C, and rotation speed 80 r/min. Based on the optimized parameters obtained, the bioreactor was operated for recovering mixed Au and Cu particles. 88.1 wt.% of Cu and 76.6 wt.% of Au were recovered. The paper contributed important information to recover precious metals from waste PCBs.

Broadband plasmon-enhanced polymer solar cells with power conversion efficiency of 9.26% using mixed Au nanoparticles

As-synthesized Au nanoparticles (NPs) composed of bone-like and rod shapes and a minority of cube and irregular spheres, generating three localized surface plasmon resonance (LSPR) peaks of 525, 575, and 775nm, were doped into poly(3, 4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) layer and realized a power conversion efficiency of as high as 9.26% in our polymer solar cells. Optical, electrical, and morphology changes induced by Au NPs were analyzed and results demonstrate that the outstanding device performance is mainly attributed to the LSPR- and scattering-induced absorption enhancement in the active layer. Besides, mixed Au NPs also decreased the bulk resistance of PEDOT:PSS, which is found to facilitate hole transport and collection.