Size Of Cu Particles Research Articles

Alkaline earth modified activated carbon supported Cu catalysts with enhanced selectivity in the hydrogenation of dimethyl oxalate to methyl glycolate.

In this work, the effect of alkaline earth metal modification on the catalytic performance of activated carbon supported Cu was investigated. The experimental results showed that the introduction of Ca and Sr improved the selectivity of methyl glycolate (MG) during hydrogenation of dimethyl oxalate (DMO) in gas phase. The optimal loading amount of Ca was 0.1 wt%, and under the optimal conditions (temperature 240 °C, pressure 2 MPa, hydrogen-ester ratio of 80, feedstock 15% DMO methanol solution, and WLHSVDMO = 0.9 h-1) the selectivity of MG was as high as 94%, and the conversion of DMO was 97%. The optimal loading of Sr was 0.2 wt% with MG selectivity up to 89% and DMO conversion of 98%. The results of catalyst characterization showed that both Ca and Sr modifications were beneficial to further reduce the particle size of Cu, improve the dispersion of Cu, increase the basicity of the catalyst, and improve the stable presence of Cu+ during the reaction process. Cu+ was beneficial to the stabilization of the MG species, in which Cu+ accounted for more in the Ca-modified catalysts Cu+/(Cu+ + Cu0) = 0.65, and in the Sr-modified ones Cu+/(Cu+ + Cu0) = 0.51. Therefore, both Ca and Sr modified catalysts showed improvement in the selectivity of MG.

Effect of pin offset on interface evolution and fracture behavior of aluminum/copper dissimilar friction stir welded

In this study, triangular prismatic threaded structural pins at different offsets were used to study the forming and performance of Al/Cu dissimilar joints. In the experiments, the Al alloy was placed on the advancing side, and the stirring pin was offset 0.5 mm, 0.8 mm, 1.0 mm, and 1.2 mm towards the Al side, respectively. The results show that sound joints can be obtained under each offset. The number and size of Cu particles in the stirred zone of the joint with a pin offset of 0.5 mm was large. The Cu particles in the stirred zone gradually refine as the stirring pin is offset towards the Al side. According to the EDS analysis, the stirring zone and interfacial intermetallic compounds (IMCs) mainly consist of Al2Cu and Al4Cu9, and a lamellar structure with IMC layers was observed on the Cu side near the Al/Cu interface. The size and number of Cu particles as well as the thickness of the IMCs layer had a significant effect on the tensile strength of the joints, with a maximum tensile strength of 203.4 MPa (equivalent to 71.3% of the Cu base metal) obtained at a pin offset of 1 mm, which was fractured in the heat-affected zone on the Al side, and the fracture surfaces demonstrated ductile fracture.

Enhanced catalytic stability of non-stoichiometric Cu–Al spinel catalysts for dimethyl ether synthesis from syngas: Effect of coordination structure

Cu–Al spinel catalysts were synthesized by various preparation methods, and its CO hydrogenation performance was evaluated. Characterization results showed that different preparation methods can effectively regulate the coordination distribution of cations in surface spinel structure. The sustained release property of Cu–Al spinel was related to its coordination structure. The catalyst containing a large amount of octahedral spinel Cu2+ ions was capable of delaying the reduction of copper, and small Cu nanoparticles (Cu NPs) were produced and highly dispersed on the defective spinel surface, which may be that the vacancy derived on the surface of defective spinel anchored small Cu NPs, which was the key to improve catalytic stability. We also discussed the real reason for poor catalytic stability, and this was due to that the easily-reducible spinel possessed extensive tetrahedral spinel Cu2+, which accelerated the reduction and release of copper, resulting in that the formed copper was unstable and aggregated readily. The Cu–Al spinel catalyst prepared by the solid phase method included octahedral coordination Cu2+ ratio as high as 59%, and the corresponding average size of Cu particles produced from spinel was measured as about 11.3 nm by N2O titration method, exhibiting enhanced stability and excellent catalytic performance.

Determining the Particle Size of Cu and Ni in Thin Cu/Ni Films using the Williamson-Hall Method

This research focuses on analyzing the particle size of a thin Cu/Ni layer produced through electroplating by varying the input voltage. The Williamson-Hall method is used to determine the particle size of the layer, and an X-ray diffractometer is used to characterize the layer. The study finds that the particle size of Cu and Ni layers with different applied voltages has different values due to various factors. The optimum voltage for the Ni layer is found to be 7.5 volts, and its overall particle size is 4.13 × 10^(-10) nm, while the particle size of Cu is 5.00 × 10^(-9) nm. The applied voltage affects the particle size produced, and the research identifies an optimum voltage at 7.5 volts.

Copper/carbon nanotube catalysts prepared by ion-exchange/electroreduction for electrocatalytic nitrate reduction: Enhanced performance and mechanism insight

Carbon-supported copper is a well-known catalyst for the electrocatalytic reduction of nitrate to ammonium/ammonia (ECRNA). However, relatively low Cu utilisation and/or restricted ECRNA performance currently limit its practical applications. Here, we report a novel carbon nanotubes (CNTs)-supported Cu catalyst (IE–Cu/CNTs) for ECRNA fabricated through ion-exchange/electroreduction method. Versus traditional CNTs-supported Cu catalysts, the IE–Cu/CNTs have a small particle size of Cu. Moreover, an increased electrochemical surface area and improved electron transfer were observed for the IE–Cu/CNTs, resulting in a 2.22-fold increase in the mass activity of the ECRNA, indicating enhanced Cu utilisation and ECRNA performance. In addition, the IE–Cu/CNTs exhibited high stability for ECRNA. Electrokinetic analysis, scavenging experiments, and online electrochemical mass spectrometry measurements confirmed that ECRNA is regulated over the IE–Cu/CNTs by both direct electron transfer reduction and indirect atomic hydrogen reduction, with the former being the main regulator. This work offers new suggestions for the design of high-performance catalysts for ECRNA and deepens the understanding of the ECRNA mechanism on Cu-based catalysts.

Densification, microstructure, and properties of W-Mo-Cu alloys prepared with nano-sized Cu powders via large electric current sintering

• The sintering densification of W-Mo-Cu alloy was achieved with a short time and relatively low temperature. • The densification of W-Mo-Cu alloy was significantly improved using nano-sized Cu powders. • W-Mo-Cu alloy contained three new phases aside from W, Mo, and Cu phases. This study rapidly fabricated a novel W-Mo-Cu alloy by large current electric field sintering at a relatively low temperature, and the effects of the powder size of Cu on the densification, microstructure, and properties were comprehensively investigated. The particle size of Cu did not influence the phase type but significantly affected the densification, microstructure, and properties. XRD and TEM results showed that the alloy contained three new phases aside from W, Mo, and Cu phases, i.e., Mo-W ordered phase, Mo-Cu solid solution, and Cu 0.4 W 0.6 intermetallic compound. Copper powders with smaller sizes were beneficial to improving the distributional homogeneity of elements and the sintering densification. Therefore, the alloy prepared with 100 nm Cu powders had a denser and more homogeneous microstructure and better comprehensive properties than that prepared with 5 μm Cu powders. Overall, the W-Mo-Cu alloy prepared with 100 nm Cu powders at 980 °C proposed the best comprehensive properties, and its relative density can reach 98% approximately.

The Effect of Copper and Copper Oxide Nanoparticles on Rainbow Trout (Oncorhynchus mykiss W.) Spermatozoa Motility after Incubation with Contaminants.

The study aimed to analyse the effect of copper nanoparticles of similar particle size of Cu and CuO and copper ions (CuSO4) on the motility parameters of rainbow trout spermatozoa after long-term exposure and compare its harmful effect. Nanoproducts of Cu and CuO (Cu NPs, CuO NPs) of primary particle size around 50 nm and ionic solution of CuSO4 were used for the study. Suspension of concentrations 0, 1, 5, 10, 25, and 50 mg Cu·L−1 of Cu NPs, CuO NPs, and CuSO4 was dissolved in an artificial seminal plasma. Milt was mixed with the prepared solution and stored in a fridge, at 6 °C, for 96 h. At the defined incubation time, spermatozoa were activated for movement, and six motility parameters were evaluated using an automated system (CASA). Increasing concentrations of Cu NPs, CuO NPs, and CuSO4 in an incubation medium in parallel decreased the percentage of motile sperm (MOT). The effect of Cu NPs and ionic copper on MOT was more deleterious than that of CuO NPs. Copper products slightly increased the velocity (VCL) compared to the control, particularly up to 24 h of storage. Linearity (LIN) was improved by three tested products, particularly CuO NPs. Generally, the motility duration was prolonged when the sperm was incubated with copper products compared to the control. Nanoproducts made from different compounds of the same elements of similar particle size have a different effect on cells. Cu NPs were more harmful than CuO NPs. The effect of Cu NPs was similar to an ionic form of CuSO4. When incubated, the copper nanoproducts and ionic form exert a slightly positive effect on spermatozoa velocity, linearity, and motility duration, particularly up to 24 h of storage.

Synthesis of flower-like MnO2 nanostructure with freshly prepared Cu particles and electrochemical performance in supercapacitors

Four types of flowerlike manganese dioxide in nano scale was synthesized via a liquid phase method in KMnO4-H2SO4 solution and Cu particles, wherein the effect of Cu particles was investigated in detail. The obtained manganese dioxide powder was characterized by XRD, SEM and TEM, and the supercapacity properties of MnO2 electrode materials were measured. The results showed that doping carbon black can benefit to better dispersion of copper particles, resulting in generated smaller size of Cu particles, and the morphology of MnO2 nanoparticles was dominated by that of Cu particles. The study of MnO2 synthesis by different sources of Cu particles showed that the size of MnO2 particles decreased significantly with freshly prepared fine copper powder compared with using commercial Cu powder, and the size of MnO2 particles can be further reduced to 120 nm by prepared Cu particles with smaller size. Therefore, it was suggested that the copper particles served as not only the reductant and but also the nuclei centre for the growth of MnO2 particles in synthesis process MnO2, and that is the reason how copper particles worked on the growth of flower-like MnO2 and electrochemical property. In the part of investigation for electrochemical property, the calculated results of b values indicated that the electrode materials have pseudo capacitance property, and the highest specific capacitance of 197.2 F g-1 at 2 mV s-1 and 148 F/g at 1 A/g were obtained for MCE electrode materials (MnO2 was synthesized with freshly prepared copper particles, where carbon black was used and dispersed in ethanol before preparation of Cu particles). The values of charge transfer resistance in all types of MnO2 materials electrodes were smaller than 0.08 Ω. The cycling retention of MCE material electrode is still kept as 93.8% after 1000 cycles.

HIGHLY LUMINESCENT CU DOPED SNO2 NANOCOMPOSITES AND THEIR PHOTOCATALYTIC APPLICATION AS EXCELLENT METHYLENE DYE REMOVAL

Cu doped SnO2 nanostructures were grown using hydrothermal method. The solution was obtained by dissolving stannous chloride in distilled water (DW) with ammonium as surfactant followed by irradiation with ultrasonic vibrations. Obtained samples were characterized by structural, morphological and optical studies. All the peaks in the Xray diffractograms are identified and indexed as structure. In pure form of Cu nanoparticles shows crystalline structures and in high concentration of Cu in SnO2 nanoparticles shows the disappearing of peaks occurring as the pH increases. Negative slope of Williamson–Hall plots indicates compressive strain. Particle size of Cu doped SnO2 nanostructures decreases with increasingthe doping concentration. An optical study shows good luminescence in visible region. A strong quantum effect was evident from the far blue shifted optical direct and indirect band gap. 80% of MO dye removed from waste water.

Production of hydrogen via methanol steam reforming over mesoporous CeO2–Cu/KIT-6 nanocatalyst: Effects of polar aprotic tetrahydrofuran solvent and ZrO2 promoter on catalytic performance

In the present study, the preparation of CeO2–Cu/KIT-6 catalysts was made by the conventional impregnation approach using a polar protic solvent (ethanol), and a polar aprotic solvent (tetrahydrofuran (THF)) as well as ethylene glycol (EG)-assisted impregnation approach. The impact of the zirconium promoter on the catalytic activity of the catalyst was evaluated in methanol steam reforming (MSR). The characterization of the prepared catalysts was carried out by XRD, XRF, BET, FE-SEM, H2-TPR, and TEM analyses. According to the characterization outcomes, the application of THF as an impregnation solvent and incorporation of ZrO2 remarkably reduced the size of Cu particles and increased the dispersion of metal species. ZrO2-promoted CeO2–Cu/KIT-6 catalyst prepared using the THF solvent showed the most suitable catalytic activity with hydrogen selectivity of 99.8%, methanol conversion of 96%, and CO selectivity of 0.7% at 300 °C. Furthermore, the catalytic stability of the synthesized catalysts was investigated over 100 h of operation.

One-step synthesis of dimethyl ether from biomass-derived syngas on CuO-ZnO-Al2O3/HZSM-5 hybrid catalyst: Combination method, synergistic effect, water-gas shift reaction and catalytic performance

The hybrid systems of CuO-ZnO-Al2O3/HZSM-5 for the one-step synthesis of DME from biomass-derived syngas were prepared by four different combination methods (granule-mixing, powder-mixing, physical coating and dual-bed fixing) and characterized by N2 adsorption, XRD, N2O titration, H2-TPR, NH3-TPD and TG techniques. The influences of combination method on the physicochemical properties and catalytic performances of hybrid catalyst were investigated, and the relationship among the combination method, the synergistic effect and the WGS reaction was discussed based on the composition features of the biomass-derived syngas (CO2-rich and H2-deficient). A maximum of CO conversion and DME yield was obtained over the hybrid catalyst prepared by granule-mixing method. There is a synergistic effect, which remarkably promotes the formation of DME, between the methanol synthesis and the methanol dehydration over the hybrid catalysts except for the hybrid system configured using the dual-bed fixing method. The WGS reaction, playing a pivotal role in the direct DME synthesis because of the in-situ produced hydrogen, relates to the combination method closely. An interaction between the two catalyst components arising in the combination process affects the properties of active sites and further the catalytic performances. The deactivation of the hybrid catalyst is ascribed mainly to the increase in the particle size of Cu in CuO-ZnO-Al2O3.

Green synthesis of Cu2O/Cu nanoparticles and conversion to Cu microparticles in one-bath reaction method for improved electrical conductivity

This work aims at investigating the conversion of Cu2O/Cu nanoparticles, prepared by green synthesis using artichoke extract, with ascorbic acid (AA) in one-bath process: a totally green method for production of pure Cu particles. Different pH values of the solution were studied to assess the conversion to Cu phase particles. It was found that by using the optimum synthesis conditions for the production of Cu2O/Cu nanoparticles and adding at the end of the synthesis AA, the conversion of Cu2O phase to pure Cu phase was possible when the pH of the solution was 8 or 10, but not when it was 12. The size of particles increased from nano to micron-sized after adding AA and multi-shaped particles with spherical, triangular, cubical and rod like shapes were formed, depending upon the pH of the synthesis solution. The electrical resistivity of the obtained pure Cu microparticles was studied after low-temperature sintering at different times and after preparing compact powder discs. After sintering for 30 min at 180 °C, discs showed resistivity of 2.9 × 10–3 Ωcm and after sintering for 60 min at 180 °C the resistivity lowered to 5.1 × 10–4 Ωcm. It can be concluded that the low resistivity of powder discs mainly depended on the size of Cu particles and sintering time, when using a fixed sintering temperature. The present synthesis of pure Cu phase microparticles is simple, convenient, environmentally friendly, cost-effective, it does not use inert gases, it is performed in aqueous media and the produced Cu particles are suitable for low electrical resistivity applications.

The effective and stable Cu–C@SiO2 catalyst for the syntheses of methanol and ethylene glycol via selective hydrogenation of ethylene carbonate

The co-production of ethylene glycol and methanol via ethylene carbonate hydrogenation derived from CO2 has attracted great concerns because of the promising chemical utilization of CO2 in large-scale. Copper-based catalysts are widely concerned in hydrogenation of ester due to the high catalytic efficiency and low cost, but the stability of copper-based catalyst is poor and needs to be further improved. In this study, the modification Cu–C@SiO2-R catalyst with graphite oxide was prepared by using Cu3(BTC)2 as the precursor and ammonia evaporation method, and was applied in ethylene carbonate hydrogenation to synthesis ethylene glycol and methanol. Furthermore, the catalysts were characterized in detail. The results showed that the Cu–C@SiO2-R catalyst was modified with graphite oxide, the average size of Cu particles was 2.9 nm and Cu particles had good dispersion. In addition, both Cu–C@SiO2-R and Cu@SiO2-R catalysts had similar ratio of Cu+/(Cu0+Cu+). In a batch reactor, under 453 K, 5 MPa, 4 h, the catalytic efficiency was 80.0% EC conversion 92.2% EG and 70.8% MeOH selectivity showing excellent catalytic performance capability of Cu–C@SiO2-R catalyst. In long-term experiment, the Cu–C@SiO2-R catalyst showed excellent stability after using for 264 h. The activity was 0.63 gEC gcat−1 h−1, and 100.0% EC conversion 99.9% EG and 85.8% MeOH selectivity could be achieved in a fixed bed. After the long-term experiment, the Cu+/(Cu++Cu0) ratio in Cu–C@SiO2-R catalyst kept at around 0.48. In contrast, the Cu+/(Cu++Cu0) ratio in Cu@SiO2-R catalyst decreased sharply from 0.48 to 0.38. The stability of the structure and the balance of valence of Cu were considered to be responsible to the stability of Cu–C@SiO2-R catalyst, because the graphite oxide not only kept the Cu+/(Cu0+Cu+) ratio stability, but also restrained the aggregation of Cu particles and loss of copper. This work provides an in-depth understanding of the stabilization mechanism of Cu and can be a reference for the industrial application of ethylene carbonate hydrogenation.

An efficient Cu/functionalized graphene oxide catalyst for synthesis of 5-substituted 1H-tetrazoles

The copper nanoparticles (Cu NPs) and amide functionalized graphene oxide (Cu-Amd-RGO) catalyst were prepared. This prepared catalyst (Cu-Amd-RGO) used for the synthesis of tetrazole derivatives. The catalyst (Cu-Amd-RGO) was characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction analysis (XRD). The average particle size of Cu was found to be 7.6 nm. The Cu-Amd-RGO catalyst exhibited excellent catalytic activity and recyclability for synthesis of tetrazoles.

Development of mesh-type Fenton-like Cu/Fex/γ-Al2O3/Al catalysts and application for catalytic degradation of dyes.

The application of nanoparticle heterogeneous Fenton-like catalysts is limited due to the requirement of filtration after reaction and possible secondary pollution. In this work, a novel mesh-type monolithic Fenton-like Cu/Fex/γ-Al2O3/Al catalyst was developed for the degradation of dyes. The Cu and Fe species are uniformly dispersed on the mesh-type anodic monolithic γ-Al2O3 supports, and the results of scanning electron microscopy and X-ray diffractometry analysis show that Fe can reduce the particle size of Cu over γ-Al2O3. The activity results show that the degradation rate of rhodamine B (RhB) reached 99.5% within 1 h using 4 × 6 cm Cu12.0/Fe2.0/γ-Al2O3/Al catalyst with 1,200 ppm H2O2 at 50 °C. The important role of •OH as a reactive oxidant was confirmed through electron spin-resonance spectroscopy and radical scavenging experiment. The hydrogen temperature programmed reduction suggests the high redox ability of Cu/Fe bimetallic catalyst is beneficial to the production of •OH. The Cu/Fe bimetallic catalyst shows excellent recyclability in a 10-cycle experiment, the degradation rate of RhB was maintained at 98% and the leaching amount of metals was lower than 0.7 mg/L. The mesh-type catalyst will be easily applied for the continuous wastewater treatment because it does not need filtration for recovery.

Highly efficient Cu/CeO2-hollow nanospheres catalyst for the reverse water-gas shift reaction: Investigation on the role of oxygen vacancies through in situ UV-Raman and DRIFTS

Self-assembled CeO2 with 3D hollow nanosphere, nanoparticle and nanocube morphologies were prepared and used to support Cu particles. The obtained samples (denoted as Cu/CeO2-hs, Cu/CeO2-np and Cu/CeO2-nc, respectively) were tested for the reverse water-gas shift (RWGS) reaction. Under the reaction conditions, V(H2):V(CO2) = 3:1 and weight hourly space velocity (WHSV) = 300,000 mL g−1 h−1, the Cu/CeO2-hs sample exhibited the best catalytic performance among the as-prepared catalysts. In order to reveal the key factors affecting the catalytic performance, the physicochemical properties of the catalysts were analyzed by XRD, BET, SEM, TEM, H2-TPR, quasi in-situ XPS and in situ UV-Raman techniques. The results point out that the particle size of Cu is not the rate-determining factor while the amount of surface oxygen vacancies is highly correlated with the catalytic reaction rate. In situ UV-Raman and in situ DRIFTS experiments indicate the formation of bidentate carbonate and formate species on oxygen vacancy sites which is thought to be the key intermediates for the RWGS reaction. These findings unravel the crucial roles of surface oxygen vacancies on CO2 adsorption and activation and also highlight a feasible way for the design of highly efficient catalysts for the important RWGS reaction in chemical industry.

Well‐Controlled Decomposition of Copper Complex Inks Enabled by Metal Nanowire Networks for Highly Compact, Conductive, and Flexible Copper Films

AbstractHighly compact and conductive Cu films are successfully fabricated by introducing mechanically robust and highly conductive metal nanowires (NWs) as fillers and optimizing amine‐based ligands in Cu complex inks. The metal NWs (AgNWs and CuNWs) dispersed in the complex inks provide networks of nucleation sites for the in situ formed Cu particles and thereby control the decomposition of Cu complex inks at low temperatures to realize Cu films with high uniformity and integrality. The high affinity between metal NWs and the in situ formed Cu element enables the growth of Cu particles along the metal NWs to create a compact structure. Besides, the amine‐based ligands such as 2‐amino‐2‐methyl‐1‐propanol (AMP), 2‐ethylhexylamine (Ethy), and hexylamine (Hexy) are varied to adjust the size of Cu particles and further improve the microstructure and conductivity of the sintered Cu films. The Cu‐Ethy complex/metal NW inks sintered at 140 °C exhibit the lowest resistivity of 14.9 µΩ cm, which is about one‐third that fabricated from the pure Cu‐AMP complex inks. The flexible light‐emitting diode circuits and V‐shaped dipole antennas prepared from the Cu complex/metal NW inks have excellent performance due to their outstanding conductivity and flexibility, showing great potential in the fabrication of cost‐effective, flexible printed electronic devices.

Enhanced performance of red mud-based oxygen carriers by CuO for chemical looping combustion of methane

The development of inexpensive oxygen carriers is of great significance for the large-scale application of chemical looping combustion technology. Red mud, a solid waste of alumina industry, is a very promising candidate as oxygen carrier for this technology due to its suitable content of Fe2O3 and low cost. In this study, the red mud oxygen carrier is modified by CuO, which is used as a cost-effective oxygen carrier for chemical looping combustion of methane. The results show that CuO as an additive strongly improve the activity and redox stability of the red mud oxygen carriers. The sample with 20 wt% content of CuO represents the highest CH4 conversion (80%), CO2 selectivity (100%) and oxidation efficiency (2.9 mmol‧g−1‧min−1) in the multiple redox testing, which are only 22%, 81% and 1.1 mmol‧g−1‧min−1 for the raw red mud. Comprehensive characterizations indicate that two kinds of Cu species (free CuO and CuFe2O4) are detected in the CuO-modified red mud after calcination at 900 ℃. Coper oxides in the both oxides can be firstly reduced to metallic Cu during the reaction with methane. The reduce Cu species may acts as active sites for methane activation and oxygen releasing, which would improve the reaction between iron oxides in red mud and methane. The element mapping indicates that the Cu species are well dispersed on the oxygen carrier after reduction by methane, which is beneficial for enhancing the catalytic function of Cu species. After the long-term redox experiment, the particle size of Cu oxides increases, while the interlacing distribution between Cu and Fe oxides are promoted. This may improve the interaction between Cu and Fe oxides and help the CuO-modified red mud to maintain relatively high stability in the successive chemical looping combustion process.

Impact of Cu particles on adsorption and photocatalytic capability of mesoporous Cu@TiO2 hybrid towards ciprofloxacin antibiotic removal

Abstract In this study, Cu@TiO2 hybrids consisting of Cu nanoparticles and mesoporous TiO2 nanoaggregates have been successfully synthesized through a simple reduction method. The Cu2+ concentration can not only engineer the mass ratio of Cu specie in the hybrids, but also tailored the size of Cu particles during this synthesis. The adsorption and photocatalytic performance towards degrading ciprofloxacin of the as-synthesized Cu@TiO2 hybrids were determined by the mass ratio as well as the Cu particle size of Cu@TiO2 in the hybrids. It was found that the Cu@TiO2 hybrid with low Cu content promoted photocatalytic performance, while high Cu content improves the adsorption efficiency. Among the as-prepared Cu@TiO2 samples, the 0.1-Cu@TiO2 sample with Cu particle content of 0.1 wt% displayed the best charge separation and transfer efficiency for photogenerated electrons and holes, and accordingly, presented the best photocatalytic efficiency, which is around 3 times higher than that for pure TiO2. In contrast, 10-Cu@TiO2 with 10 wt% Cu showed the highest adsorption capability (888.57 mg/g, about 5 times larger than that of TiO2), since it had the most negative zeta potential, although its Brunauer-Emmett-Teller surface area was less than that of the pure TiO2 material. This work has not only developed a facile approach to prepare Cu-based hybrids, but also reveals how Cu@TiO2 hybrids can be tailored and optimized for adsorption and photocatalytic removal of antibiotic pollution.

Size-Controllable Synthesis of Bimodal Cu Particles by Polyol Method and Their Application in Die Bonding for Power Devices

A simple and large-scale polyol method was utilized to successfully synthesize bimodal Cu particles in the air. The size, size distribution, and morphology of Cu particles were determined by the reaction parameters, such as Cu source and additives. The insoluble Cu source is suitable for the formation of bimodal Cu particles as they provide a slow and steady supply of fresh Cu nuclei, which modify the nucleation and growth of Cu particles. In addition, sodium sulfide (Na2S) additive has the ability to control the size of Cu particles due to its reduction capability. As-synthesized bimodal Cu particles were used to fabricate sintered Cu joints for high-power electronic packaging. The results show that the shear strength of sintered Cu joints was determined by the size and size distribution of Cu particles. Sintered Cu joints with high shear strength above 20 MPa can be readily achieved at 300 °C with a slight applied pressure of 0.4 MPa. This strength is superior to joints utilizing nanoparticle Cu paste. The size-matching effect and the high oxidation resistance of the bimodal Cu particles were attributed to the excellent mechanical performance of the sintered Cu joints. Our results indicate that this affordable paste utilizing bimodal Cu particles of a suitably designed size and with a uniform distribution is highly promising as the die-bonding material for next-generation power devices.