Ag Deposition Research Articles

Cyanide-free silver electrodeposition with polyethyleneimine and 5,5-dimethylhydantoin as organic additives for an environmentally friendly formulation

The influence of polyethyleneimine (PEI) as additive for cyanide-free silver bath, in combination with 5,5-dimethylhydantoin (DMH) as complexing agent, is studied. Cyclic voltammetry (CV) measurements are used to characterize the electrochemical behaviour of the Ag/DMH complex. The Ag electrodeposition from the cyanide-free silver-plating bath is analysed by CVs and the process is optimized varying the PEI concentration. Chronoamperometry is then used to investigate the electrodeposition mechanism, which is found to be a three-dimensional diffusion-controlled nucleation and growth mechanism, according to the Scharifker–Mostany’s model. Smoother, brighter and blue coloured silver deposits are obtained in the presence of PEI in a Hull’s cell test, at low density current. Eventually, the influence of nitrate anion is also investigated. The presence of nitrate increases the range of current density allowing for an effective Ag deposition.

Simultaneous Enhancement in Visible Transparency and Electrical Conductivity via the Physicochemical Alterations of Ultrathin-Silver-Film-Based Transparent Electrodes.

A methodology for the simultaneous modulation of the chemical and physical states of an amorphous TiOx layer surface and its impact on the subsequent deposition of a polycrystalline Ag layer are presented. The smoothened TiOx layer surface comprising chemically altered, oxygen-deficient states serves as a nucleating platform for Ag deposition, facilitating a marked increase (∼75%) in the nucleation number density, which strongly enhances the wettability of ultrathin Ag layers. The physically smoothened TiOx/Ag interface further reduces the optical and electrical losses. When the proposed methodology is applied to TiOx/Ag/ZnO transparent conductive electrodes (TCEs), exceptional TCE properties are yielded owing to the simultaneous improvement in visible transparency and electrical conductivity; specifically, a record-high 0.22 Ω-1 Haacke figure of merit is realized. TCEs are prepared on flexible substrates to verify their applicability as stand-alone flexible transparent heaters and as integrated heaters within electrochromic devices to enhance color-switching reactions.

Construction of Z-scheme CdS/Ag/TiO2 NTs photocatalysts for photocatalytic dye degradation and hydrogen evolution

The ternary CdS/Ag/TiO2 NTs photocatalysts with indirect Z-scheme heterojunctions were synthesized by the photoreduction deposition of Ag and successive ionic layer adsorption and reaction (SILAR) of CdS on TiO2 nanotube arrays (TiO2 NTs). The elemental composition, microstructure, photoresponse and photoelectrochemical property of the photocatalyst were systematically characterized. The results proved that compared with binary heterojunction, the light absorption range of the ternary CdS/Ag/TiO2 NTs photocatalyst was significantly extended, and the photoelectron transportation efficiency was improved. Under sunlight irradiation, the photocatalytic capacity was verified by investigating the photodegradation of MB and RhB dyes. The CdS/Ag/TiO2 NTs exhibited the optimal photocatalytic performance with the degradation efficiency of 82.24% for RhB and 100% for MB. The synthesized CdS/Ag/TiO2 NTs had high photocatalytic hydrogen evolution capacity and stability, and the hydrogen production reached 806.33 μmol·cm−2. Based on the results of electron spin resonance spectroscopy (ESR) and free radical trapping, the photocatalytic reaction mechanism was explained. The synthesis of ternary CdS/Ag/TiO2 NTs provides a practical reference and guidance for designing high-efficient photocatalysts with Z-scheme heterojunctions toward solar energy development for H2 generation, pollutant remediation and photoelectric conversion.

Antifouling superhydrophobic surfaces with bactericidal and SERS activity

• A multifunctional superhydrophobic surface is fabricated using fluorine-free eco-friendly materials. • The superhydrophobic surface is extremely repellent to liquids, including most liquid food. • Deposition of Ag imparted SERS and antibacterial activity. • The superhydrophobic surface reduces residual food waste. • The superhydrophobic surface showed excellent chemical stability. Fouling and contamination of surfaces are prevailing challenges humanities facing today in fields such as healthcare, hospitality, and food manufacturing. These challenges strongly motivate the development of multifunctional surfaces with antifouling and antimicrobial properties that are coupled with sensing capabilities. To address this challenge, we prepared a multifunctional superhydrophobic surface using eco-friendly materials: polydimethylsiloxane (PDMS) and carnauba wax. After deposition of a thin film of Ag, the surface gained surface-enhanced Raman scattering (SERS) activity and bactericidal property. The multifunctional superhydrophobic surface showed extreme liquid repellency towards water and common liquid food. The strong SERS activity enabled the detection of adulterant rhodamine B in a sausage down to a nanomolar level. Notably, the surface showed excellent bactericidal activity towards two common bacteria, E. coli, and S. aureus, significantly reducing their adhesion and killing. Additionally, the surface showed anti-fouling behavior against common liquid food, and even towards sticky foods such as yogurt, honey, and pomegranate sauce, reducing residual food by >97 %. Furthermore, the superhydrophobic surface showed excellent chemical stability in dynamic and static flow conditions and leaching of Ag in neutral and basic solutions was minimal.

Preparation of a novel bi-layer modified alumina-based hybrid material and its effect on the thermal conductivity enhancement of polymer composites

In this work, a new kind of double layers modified alumina-based hybrid (silver@copper@alumina (Ag@Cu@Al2O3) hybrid) was successfully synthesized through the two-step layer-by-layer process. First, copper (Cu) nanoparticles were assembled onto alumina (Al2O3) particles by reduction of Cu2+. Second, Ag@Cu@Al2O3 hybrids were assembled via Ag deposition on the surface of Cu@Al2O3 particles. The obtained Ag@Cu@Al2O3 hybrids served as thermally conductive fillers to greatly boost the thermal conductivity of poly (dimethylsiloxane) (PDMS). The thermal conductivity reached 1.465 W m−1 K−1 at 85 wt% filler loading. The thermal conductivity of PDMS matrix was increased more than 7 times by the addition of Ag@Cu@Al2O3 hybrid, which was much higher than single layer modified alumina-based hybrids (Ag@Al2O3 and Cu@Al2O3 hybrids) and virgin Al2O3 particle. The effect of double layers modified filler, single layer modified filler and virgin filler on the thermal conductivity of PDMS matrix was discussed in detail and the mechanism of these fillers for improving thermal conductivity was studied through Foygel's thermal conduction model. Otherwise, electric, mechanical and thermal properties of Ag@Cu@Al2O3/PDMS composites were also further tested and analyzed.

Biodegradable Nanohybrid Materials as Candidates for Self-Sanitizing Filters Aimed at Protection from SARS-CoV-2 in Public Areas.

The COVID-19 pandemic has raised the problem of efficient, low-cost materials enabling the effective protection of people from viruses transmitted through the air or via surfaces. Nanofibers can be a great candidate for efficient air filtration due to their structure, although they cannot protect from viruses. In this work, we prepared a wide range of nanofibrous biodegradable samples containing Ag (up to 0.6 at.%) and Cu (up to 20.4 at.%) exhibiting various wettability. By adjusting the magnetron current (0.3 A) and implanter voltage (5 kV), the deposition of TiO2 and Ag+ implantation into PCL/PEO nanofibers was optimized in order to achieve implantation of Ag+ without damaging the nanofibrous structure of the PCL/PEO. The optimal conditions to implant silver were achieved for the PCL-Ti0.3-Ag-5kV sample. The coating of PCL nanofibers by a Cu layer was successfully realized by magnetron sputtering. The antiviral activity evaluated by widely used methodology involving the cultivation of VeroE6 cells was the highest for PCL-Cu and PCL-COOH, where the VeroE6 viability was 73.1 and 68.1%, respectively, which is significantly higher compared to SARS-CoV-2 samples without self-sanitizing (42.8%). Interestingly, the samples with implanted silver and TiO2 exhibited no antiviral effect. This difference between Cu and Ag containing nanofibers might be related to the different concentrations of ions released from the samples: 80 μg/L/day for Cu2+ versus 15 µg/L/day for Ag+. The high antiviral activity of PCL-Cu opens up an exciting opportunity to prepare low-cost self-sanitizing surfaces for anti-SARS-CoV-2 protection and can be essential for air filtration application and facemasks. The rough cost estimation for the production of a biodegradable nanohybrid PCL-Cu facemask revealed ~$0.28/piece, and the business case for the production of these facemasks would be highly positive, with an Internal Rate of Return of 34%.

Structure-Element Surface Modification Strategy Enhances the Antibacterial Performance of Zr-BMGs.

Zirconium-based metallic glasses (Zr-BMGs) have attracted tremendous attention in healthcare fields, especially in the design of surgical tools and orthopedic implants, due to their unique amorphous structure; however, the application of Zr-BMG-based medical devices is hindered by bacterial contamination. Here, a structure-element strategy is proposed to improve the antibacterial performance of Zr-BMGs by surface laser nanostructuring and silver nanoparticle (AgNP) deposition. The laser nanostructuring process generates a disordered nanoparticle structure (NP) and laser-induced periodic surface structure (LIPSS) to decrease the surface bacterial adhesion and increase the internal antimicrobial ion release. Moreover, after Ag deposition and hydrogen peroxide (H2O2) treatment, the antibacterial adhesion ability of the Zr-BMG surface can be further improved without any influence on the crystallization of Zr-BMGs and the release of antibacterial copper/nickel (Cu/Ni). The antibacterial effect of the LIPSS and the NP surfaces presents over 90% bacterial killing ratio, which is superior to that of the naked Zr-BMGs with less than 60% bacterial killing ratio. In vitro and in vivo tests show that the Ag-deposited and H2O2-treated LIPSS surfaces exhibit an optimal balance between the antibacterial property and the biocompatibility compared with the polished, NP structured or LIPSS structured surfaces. It is assumed that such structure-element surface modification strategy can improve the antibacterial activity of metal-containing surgical tools and orthopedic implants, improving the success rate of medical treatment.

Peroxymonosulfate enhanced photoelectrocatalytic oxidation of organic contaminants and simultaneously cathodic recycling of silver

Degradation of organic contaminants with simultaneous recycling of Ag+ from silver-containing organic wastewater such as photographic effluents is desired. Although photoelectrocatalysis (PEC) technology is a good candidate for this type of wastewater, its reaction kinetics still needs to be improved. Herein, peroxymonosulfate (PMS) was employed to enhance the PEC kinetics for oxidation of phenol (PhOH) at the anode and reduction of Ag+ at the cathode. The degradation efficiency of phenol (PhOH, 0.1 mmol/L) was increased from 42.8% to 96.9% by adding 5 mmol/L PMS at a potential of 0.25 V. Meanwhile, the Ag (by wt%) deposited on the cathode was 28.1% (Ag2O) in PEC process, while that of Ag (by wt%) was 69.7% (Ag0) by adding PMS. According to the electrochemistry analysis, PMS, as photoelectrons acceptor, enhances the separation efficiency of charges and the direct h+ oxidation of PhOH at the photoanode. Meantime, the increasing cathode potential avoided H2 evolution and strongly alkaline at the surface of cathode, thus enabling the deposition of Ag+ in the form of metallic silver with the help of PMS. In addition, PMS combined with PEC process was effective in treating photographic effluents.

Enhanced thermal conductivity of silicone rubber via synergistic effects of polydopamine modification and silver deposition on boron nitride

It is great significance to develop polymeric composites with effective heat dissipation and high electrical insulation for devices in electronics fabrication. Herein, we fabricated silicone rubber (SR) composites with large thermal conductivity (TC) and high electrical insulation by utilizing the synergistic effects of polydopamine (PDA) modification and Ag nanoparticles deposition on the surface of BN sheets, denoted as BN-PDA-Ag/SR composites. Finally, the fabricated BN-PDA-Ag/SR composite at a filler content of 30 vol% exhibited a TC up to 0.75 W/(mK), which was about 5.76 times of pure SR, while it holded a low AC conductivity of 1.89 × 10-11 S/cm at 100 Hz. Overall, the synergistic effects of PDA modification and Ag deposition on BN sheets proposed in this work is an easy and eco-friendly avenue for the preparation of high-performance thermally conductive and insulating polymeric composites for advance electronic equipments.

Antibacterial Electroconductive Composite Coating of Cotton Fabric.

Graphene oxide (GO) was deposited on a cotton fabric and then thermally reduced to reduced graphene oxide (rGO) with the assistance of L-ascorbic acid. The GO reduction imparted electrical conductivity to the fabric and allowed for electrochemical deposition of Ag° particles using cyclic voltammetry. Only the Ag°/rGO composite coating imparted antibacterial properties to the fabric against Escherichia coli and Staphylococcus aureus. Ag°/rGO-modified fibers were free of bacterial film, and bacterial growth inhibition zones around the material specimens were found. Moreover, Ag°/rGO-modified fabric became superhydrophobic with WCA of 161°.

Enhancement in Photovoltaic Performance of Solar Cells by Electrostatic Adsorption of Dyes on ZnO Nanorods.

ZnO nanorods were formed by chemical bath deposition on fluorine–doped tin oxide (FTO) glass and the photovoltaic performance of ZnO-based dye-sensitized solar cells (DSCs) was investigated. A DSC with 8 h-grown ZnO nanorods showed a higher power conversion efficiency (PCE) than devices with 4, 6, and 10 h-grown ones. Further improvement in PCE was achieved in a cell with a silver-ion-deposited ZnO/FTO electrode. By deposition of Ag+ on the surface of the 8 h-grown ZnO nanorods, the dye-loading amount increased by approximately 210%, compared to that of pristine ZnO nanorods, resulting in a 1.8-times higher PCE. A DSC with the pristine ZnO/FTO electrode showed a PCE of 0.629%, while in a device with the silver-ion-deposited ZnO/FTO, the PCE increased to 1.138%. In addition, interfacial resistance at the ZnO/dye/electrolyte was reduced to approximately 170 Ω from 460 Ω for the control cell with the pristine ZnO/FTO. We attributed the higher dye-loading amount in the silver-ion-deposited ZnO/FTO to the electrostatic attraction between the positively charged ZnO and carboxylate anions (–COO−) of the N719 dyes.

Hierarchically Z-scheme photocatalyst of {0 1 0}BiVO4/Ag/CdS with enhanced performance in synergistic adsorption-photodegradation of fluoroquinolones in water

In this work, the sheet-like BiVO4 with a higher exposure ratio of {010} facets was synthesized by the addition of TiCl3, and the ratio of (040)/(011) on {010}BiVO4 was 2.85 times higher than that of normal decahedral BiVO4. Accordingly, the {010}BiVO4/Ag/CdS all-solid-state Z-scheme heterojunction was further constructed by photoreduction of Ag and chemical deposition of CdS on the well prepared {010}BiVO4 successively. The performance and mechanism of {010}BiVO4/Ag/CdS in synergistic adsorption-photodegradation of fluoroquinolones (FQs) from water were investigated in detail. The adsorption-photodegradation could be divided into three processes: adsorption, surface degradation, and solution degradation, with the rate constants of 0.118, 0.029, and 0.012 min−1, respectively. Accordingly, the adsorption was a rapid process due to the combined CdS in this composited photocatalyst had a high affinity to FQs to achieve an adsorption equilibrium on the surfaces<30.0 min. Besides, {010}BiVO4/Ag/CdS had a better separation efficiency of photogenerated electron-hole pairs than BiVO4/Ag/CdS, because the enriched {010} facets of {010}BiVO4 caused more BiVO4/Ag/CdS ternary structure formed, and>90% photodegradation efficiency for five FQs (C0 = 0.062 mmol/L) was thus obtained within 60.0 min. The radical trapping and EPR results showed that holes and superoxide radicals were the main active species for FQs photodegradation. In summary, {010}BiVO4/Ag/CdS achieved an enhanced performance in synergistic adsorption and photodegradation of organic contaminants from water, and a talented photocatalyst was thus provided in water and wastewater treatment.

Synthesis of novel muscovite loaded nano Ag/Cu2-xFexO composites with excellent visible-light responsive photocatalysis

Muscovite loaded Cu2O nanosphere composites with Fe3+ doping and Ag deposition were successfully synthetized by a simple chemical reduction method. The composites were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR) spectrometer, scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) technique, transmission electron microscope (TEM), photoluminescence spectra (PL) and UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS). Meanwhile, the photocatalytic performance and photocatalytic mechanism of the samples were investigated by photodegradation of methyl orange (MO) dye under visible light irradiation. The Cu2O nanosphere composites co-modified by Ag, Fe3+ and muscovite showed the best photocatalytic activity, which may originate from both the enhancement of utilization of Cu2O photocatalyst and the reduction of recombination of electrons and holes in the natural environment.

Weak-light-driven Ag–TiO2 photocatalyst and bactericide prepared by coprecipitation with effective Ag doping and deposition

TiO2 can mainly absorb ultraviolet light (UV) and thus the strong light irradiation of photocatalyst is highly needed to obtain efficient charge carrier (electrons and holes) production for subsequent reactions. In this paper, Ag–TiO2 nanoparticles with high Ag dispersibility were prepared by different Ag contents (0–6 at. %) and calcination temperatures (200–600 °C) using a coprecipitation method. Results showed that Ag inhibited the transformation of anatase to rutile TiO2, resulting in the decreased Eg and increased amounts of chemisorbed hydroxyl oxygen as well as oxygen vacancy. 2% Ag–TiO2 possessed the best and high photocatalytic efficiency under weak UV and visible light irradiation (15W). The bactericidal activity of Ag–TiO2 nanoparticles was also enhanced compared with pure TiO2, and further enhanced with Ag content. The superior performance was mainly ascribed to the synergistic effect of Ag and TiO2.

Architecting an indirect Z-scheme NiCo2O4@CdS–Ag photocatalytic system with enhanced charge transfer for high-efficiency degradation of emerging pollutants

Bimetallic oxides with spinel structure show great prospects in the photocatalysis owing to many active sites. Herein, a novel 500NiCo2O4@CdS–5%Ag composite was fabricated via a feasible strategy. Interestingly, the combination with NiCo2O4 could significantly enhance the absorption ability of CdS for visible light. Benefiting from the formation of heterojunction structure between NiCo2O4 and CdS, the recombination of photogenerated electrons and holes was remarkably restrained. As an effective mediator, deposition of Ag could further promote the transfer of photogenerated charge carriers, thereby accelerating the reaction rate. Meanwhile, light absorption capacity of composite was also improved, owing to the surface plasmon resonance effect of metallic Ag. More importantly, 500NiCo2O4@CdS–5%Ag composite with great stability displayed an excellent performance in the photocatalytic degradation of OFX, and its highest removal efficiency was as high as 99.14%. Possible degradation pathways of OFX were given, and most of OFX could be degraded into CO2, H2O and other by-products with no toxicity. Significantly, the separation and transfer of photogenerated charge carriers followed indirect Z-scheme heterojunction mechanism. The O2−, OH and 1O2 were main active species in photocatalytic reaction system. All in all, current work inspired some new ideas for designing novel photocatalytic system in wastewater treatment.

Mesh size control in forming an Ag/AgO nano-network structure for transparent conducting application

The variation behaviors of the morphology, transmission, and sheet resistance of the surface Ag/AgO nano-network (NNW) structures fabricated under different illumination conditions and with different Ag deposition thicknesses and thermal annealing temperatures in forming initial Ag nanoparticles (NPs) are studied. Generally, an NNW structure with a smaller mesh size or a denser branch distribution has a lower transmission and a lower sheet resistance level. Under the fabrication condition of a broader illumination spectrum, a lower thermal annealing temperature, or a thicker Ag deposition, we can obtain an NNW structure of a smaller mesh size. The mesh size of an NNW structure is basically controlled by the seed density of Brownian tree (BT) at the beginning of light illumination. A BT seed can be formed through a stronger local localized surface plasmon resonance for accelerating Ag oxidation in a certain region. Once an Ag/AgO BT seed is formed, the surrounding Ag NPs are reorganized to form the branches of a BT. Multiple BTs are connected to form a large-area NNW structure, which can serve as a transparent conductor. Under the fabrication conditions of a broader illumination spectrum, 3 nm Ag deposition, and 100 °C thermal annealing, we can implement an NNW structure to achieve ∼1.15 μm in mesh size, ∼90 Ω sq−1 in sheet resistance, and 93%–77% in transmittance within the wavelength range between 370 and 700 nm.

Influence of Ag Photodeposition Conditions over SERS Intensity of Ag/ZnO Microspheres for Nanomolar Detection of Methylene Blue.

Surface enhanced Raman spectroscopy (SERS) is considered a versatile and multifunctional technique with the ability to detect molecules of different species at very low molar concentration. In this work, hierarchical ZnO microspheres (ZnO MSs) and Ag/ZnO MSs were fabricated and decorated by hydrothermal and photodeposition methods, respectively. For Ag deposition, precursor molar concentration (1.9 and 9.8 mM) and UV irradiation time (5, 15, and 30 min) were evaluated by SEM, TEM, X-ray diffraction and Raman spectroscopy. X-ray diffraction showed a peak at 37.9° corresponding to the (111) plane of Ag, whose intensity increases as precursor concentration and UV irradiation time increases. SEM images confirmed the formation of ZnO MSs (from 2.5 to 4.5 µm) building by radially aligned two-dimensional ZnO nanosheets with thicknesses below 30 nm. The Raman spectra of Ag/ZnO MSs exhibited a vibration mode at 486 cm−1 which can be directly associated to Ag deposition on ZnO MSs surface. The performance of SERS substrate was evaluated using rhodamine 6G. The SERS substrate grown at 9.8 mM during 30 min showed the best SERS activity and the ability to detect methylene blue at 10−9 M.

The finite-difference time-domain (FDTD) guided preparation of Ag nanostructures on Ti substrate for sensitive SERS detection of small molecules

Surface-enhanced Raman Scattering (SERS) has become a powerful analytical technique for highly sensitive detection of target molecules. Its performance, however, is heavily dependent on the substrates. Relatively low sensitivity for small molecules and poor reproducibility in quantitative analysis are often encountered in most of nanoparticle modified SERS substrate. The present work starts by theoretical investigation of the electromagnetic field enhancement by nanomaterials of coinage metals with different sizes. The finite-difference time-domain (FDTD) simulation results revealed that the Ag NPs with the size around 100 nm exhibit the strongest SERS effect and the ‘Ag-Ag’ gaps have shown higher electromagnetic field enhancement than that of the ‘Ag-Ti’ gap. Subsequently, a multilayered Ag nanoparticles SERS substrate (or other coinage metals) was prepared by a two-step electroless deposition of Ag on Ti substrate. This was achieved by in situ reduction of Ag precursor to subsequently form a Ag nanoflake (Ag NF) layer and a Ag nanoparticle (Ag NPs) layer on the Ti base (Ti/AgNFs/AgNPs). The as-prepared SERS substrate showed a substantially enhanced SERS effect for small molecule detection and detection limit as low as 1.0 × 10-17 M for picric acid (PA), 1.0 × 10-14 M for p-nitrotoluene (PNT) and 1.0 × 10-6 M for uric acid (UA) were obtained respectively. The facile method developed in this work should be widely applicable for in-situ preparation of other SERs substrates.

Enhanced Photocurrent of the Ag Interfaced Topological Insulator Bi2Se3 under UV- and Visible-Light Radiations.

Bi2Se3 is a topological quantum material that is used in photodetectors, owing to its narrow bandgap, conductive surface, and insulating bulk. In this work, Ag@Bi2Se3 nanoplatelets were synthesized on Al2O3(100) substrates in a two-step process of thermal evaporation and magnetron sputtering. X-ray diffractometer (XRD), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, and x-ray photoelectron spectroscopy (XPS) revealed that all samples had the typical rhombohedral Bi2Se3. Field-emission scanning electron microscopy (FESEM)-energy dispersive x-ray spectroscopy (EDS), XPS, and HRTEM confirmed the presence of the precipitated Ag. The optical absorptance of Bi2Se3 nanoplatelets in UV-visible range decreased with the Ag contents. Results of photocurrent measurements under zero-bias conditions revealed that the deposited Ag affected photosensitivity. A total of 7.1 at.% Ag was associated with approximately 4.25 and 4.57 times higher photocurrents under UV and visible light, respectively, than 0 at.% Ag. The photocurrent in Bi2Se3 at 7.1 at.% Ag under visible light was 1.72-folds of that under UV light. This enhanced photocurrent is attributable to the narrow bandgap (~0.35 eV) of Bi2Se3 nanoplatelets, the Schottky field at the interface between Ag and Bi2Se3, the surface plasmon resonance that is caused by Ag, and the highly conductive surface that is formed from Ag and Bi2Se3. This work suggests that the appropriate Ag deposition enhances the photocurrent in, and increases the photosensitivity of, Bi2Se3 nanoplatelets under UV and visible light.

Constructing a novel AuAg/BiOBr/BaTiO3 composite via selective decoration route with enhanced visible-light photoatalytic performance

In this work, the BaTiO3 nanoparticles (hole acceptor) were firstly decorated on the surface of BiOBr nanoplates by hydrothermal method, and then AuAg alloy nanoparticles (electron acceptor) are selectively deposited on the uncovered surface of BiOBr nanoplates to form AuAg/BiOBr/BaTiO3 composite using visible-light photodeposition method. It is found that the BaTiO3 (∼55 nm) and AuAg (7–16 nm) nanoparticles are uniformly dispersed on the BiOBr surface, which are disconnected without direct contact between them. The visible-light photocatalytic degradation and reduction activity of products were evaluated using methyl orange (MO), acid orange 7 (AO7), rhodamine B (RhB) and Cr(VI) as the target reactant. After the combination of BiOBr with BaTiO3, the BiOBr/BaTiO3 composites exhibit enhanced photocatalytic activity. When the content of BaTiO3 reaches about 10%, the BiOBr/10%BaTiO3 composite exhibits best photocatalytic efficiency. Notably, the selective deposition of Au, Ag and AuAg alloy nanoparticles leads to the further enhancement of photocatalytic activity for BiOBr/10%BaTiO3 composite, and the optimal photocatalytic activity can be achieved over AuAg/BiOBr/10%BaTiO3 sample. The AuAg/BiOBr/10%BaTiO3 composite is demonstrated to be an stable photocatalyst, which also exhibits efficient synergistic photocatalytic activity for the purification of the RhB/Cr(VI) and AO7/Cr(VI) mixture. The photogenerated charges performance of products was measured by electrochemical work station. The main active species participated in the photocatalytic reaction of AuAg/BiOBr/10%BaTiO3 was detected. Based on above results, the synergistic modification mechanism of BaTiO3 and AuAg alloy nanoparticles on the photocatalytic activity of BiOBr was proposed.