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The proposed work reports a facile chemical reduction method for synthesizing the hierarchical silver-nickel core-shell nanowire structures with controllable morphologies by varying the Ag concentration. The growth of Ni shells around the Ag core to make thorny and smooth Ag-Ni core-shell nanowires is studied for addressing electromagnetic interference (EMI). The synthesized Ag-Ni nanowires show better EMI shielding effectiveness (SE) than Ni nanowires with much-improved absorption loss (SE A). Due to high electrical conductivity (8630 S cm−1), magnetic permeability (44.1 emu/g), and heterojunction core-shell interfaces, the bimetallic nanowires flakes exhibit exceptional average EMI SE of 90.5 dB in the X-band frequency range (8–12 GHz) with a thickness of 0.11 mm, taking specific EMI SE to 822.72 dB/mm. In addition, the EMI shielding performance of the smooth Ag-Ni nanowires showed a 45% enhancement in SE A with marginal change in reflection loss (SE R) compared to the thorny ones, indicating high absorption of EM waves. The unique core-shell nanowires with high aspect ratio with tunable physical properties can be ideal candidates for futuristic applications in microwave absorption and electromagnetic interference shielding. [Display omitted] • A facile chemical reduction method was employed to synthesis Ag-Ni core-shell nanowires with various morphological features. • The effect of morphology of Ag-Ni core-shell nanowires on EMI shielding was studied. • The fabricated flakes showed a superior specific EMI SE of 822.72 dB/mm in the X-band frequency range. • Enhanced electrical conductivity, optimal magnetic permeability, and multiple interfaces led to high absorption loss. [ABSTRACT FROM AUTHOR]

The exponential growth of the Li-ion battery (LIB) market necessitates the development of environmentally friendly and economically viable recycling technologies. One of the approaches for recycling and selective recovery of critical battery components is the hydrometallurgical method. Despite its effectiveness, this technology has notable drawbacks, including environmental pollution caused by corrosive waste, high energy consumption, and complexity. Herein we present a highly efficient mechanochemically (MC) induced acid leaching process that enables the extraction of transition metals as water-soluble salts from cathode materials of different and mainly used chemistries such as LiCoO 2 , LiMn 2 O 4 , and Li(CoNiMn)O 2. The described method utilizes HNO 3 , H 2 SO 4 , and HCl mineral acids to leach transition metal composites obtained by MC reduction and delithiation processes. The presented technology achieves a significant material dissolution efficiency of more than 95 % at low acid concentrations at room temperature. Furthermore, it was concluded that the mechanochemical pretreatment step plays a crucial role in reducing particle sizes as well as for the chemical reduction of d-elements in the cathode materials to lower electrochemical charging states which greatly enhances the effectiveness of the leaching process. This advancement brings us closer to achieving ecological and economic feasibility in recycling Li-ion batteries. • Mechanochemically induced reduction process can be used for battery recycling. • Cathode materials transformed to metal composites mechanochemically. • Method attains over 95 % dissolution with mineral acids at room temperature. • Mechanochemical reduction enhances the acid leaching efficiency of cathodes. [ABSTRACT FROM AUTHOR]

SnAgCu alloys with low melting points and solderability are good candidates for Sn/Pb eutectics. In this paper, Sn-3.0Ag-0.5Cu nanoalloy powders were prepared by a chemical co-reduction method. The microscopic morphology, phase composition and melting behavior of the powders were analyzed with emphasis on the effect of surfactants on the powder particle size. The results showed that the average particle size of the powder was well controlled by the synergistic effect of the surfactants 1,10-phenanthroline and PVP, and the average particle size of the powder obtained was about 19 nm when the mass ratio of 1,10-phenanthroline to PVP was 4 and the addition amount was 10% of the precursor mass. The powder consists of three phases β-Sn, Ag 3 Sn, and Cu 6 Sn 5. The initial melting temperature of the powder is approximately 185.8 °C, which is close to the melting point of conventional Sn/Pb solder (183 °C). • Sn-3.0Ag-0.5Cu nanoparticles have a low starting melting temperature of approximately 185.8 °C. • Combination surfactants have a synergistic effect, reducing the amount of surfactant in the system. • Simple preparation process, easy to handle. [ABSTRACT FROM AUTHOR]

In this work, synthesis of copper/reduced graphene oxide composites to increase the electrical conductivity of copper matrix has been carried out. Pure copper particles were mixed with 0.28 wt%, 1.1 wt% and 2.5 wt% graphene oxide (GO) contents. Different reduction methods were chosen to synthetize the Cu/rGO composite material: chemical reduction with hydrazine, thermal treatment at 815 °C in argon atmosphere. Characterization of the Cu/rGO composite disks was carried out by optical microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy. Vickers Hardness and the electrical conductivity measured by Van der Pauw method of the Cu/rGO composites were analyzed. All the Cu/rGO disks showed lower hardness values than the Cu matrix. Microstructure of Cu/rGO composites is dominated by the presence of pores where GO agglomerates are accumulated and whose distribution and magnitude depends on the weight percentage of GO and the reduction process. Porosity percentage and pore size of Cu/rGO disks increase with GO content. Combination of chemical reduction with thermal treatment provides the most homogeneous microstructures with the smallest pore size and porosity percentage. Combination of both reduction treatments promotes more pathways for carrier transport within the reduced graphene oxide network structure, expanding areas of long-range conjugated structures and, consequently, increasing the electrical conductivity in the rGO/copper composites. Our research evidences that the Cu/rGO composites after chemical and thermal reduction increases the electrical conductivity, independently on the GO content, with respect to the pure copper matrix. • Effective chemical-thermal reduction of graphene oxide in copper matrix is achieved. • C/O ratio of 6.9 in Cu/rGO composites after reduction treatments is obtained. • Increased electrical conductivity in Cu/rGO due to long-range sp2 structures. [ABSTRACT FROM AUTHOR]

In this work, Eu-doped La 3 Si 8 N 11 O 4 phosphors with different doping concentrations are fabricated by solid state reaction method. A broad and asymmetric emission band that covers the wavelength range of 425–550 nm is observed. X-ray diffraction Rietveld refinement and X-ray absorption near edge structure (XANES) analyses reveal the co-existence of both trivalent and divalent states of Eu. By coating the phosphor particles with an ultrathin carbon layer using CVD technique, followed by an annealing in N 2 at 1600 °C, the trivalent ions Eu3+ are reduced to Eu2+, resulting in a significant enhancement of quantum efficiency, both internal and external, and absorption efficiency. The application of the La 3 Si 8 N 11 O 4 :Eu in white light-emitting diodes is tested by coating the phosphor onto a near-UV LED chip in combination with the red-, green- and blue-emitting phosphors ([Ca, Sr]AlSiN 3 :Eu, ®-Sialon:Eu and BaMgAl 10 O 17 :Eu, respectively). It is demonstrated that the presence of the La 3 Si 8 N 11 O 4 :Eu phosphor significantly enhances the color rendering index of the device, showing its great potential for wLEDs applications. • The microstructure evolution of La 3 Si 8 N 11 O 4 : Eu phosphor was clarified in detail. • Both trivalent and divalent states of Eu exist in La 3 Si 8 N 11 O 4 : Eu. • Eu3+ was reduced to Eu2+ by carbon coating and annealing. • The highest quantum efficiency was achieved in the treated phosphors. [ABSTRACT FROM AUTHOR]

This paper presents a review in gold nanoparticles focusing on chemical reduction synthesis mechanisms. We hope to aid students and researchers starting in the nanotechnology field by compiling the most used synthesis methods, so they can select the ones that best suit them. The compiled information in this paper approached the following methods: Turkevich Method; Synthesis with NaBH 4 with/without citrate; Seeding- Growth; Synthesis by Ascorbic Acid; Green Synthesis; Brust-Schiffrin; and synthesis using other reducing agents. Papers that had clear synthesis information were selected for this work, but that doesn't mean they were synthesis focused. Over 150 papers were analyzed. After compiling the information for these papers, we can conclude that nanoscience is revolutionizing all the areas that are applied to. Image 1 • This paper presents a review in gold nanoparticles focusing on synthesis mechanisms. • From the data gathered, a rapid increase in publications is observed. • The most important factor is that the end result has a narrow size distribution. • The most used is the Turkevich methodology that yields particles in the 10 nm range. [ABSTRACT FROM AUTHOR]

Formaldehyde is one of the most serious threats to human health owing to the wide-spread of indoor decoration of modern buildings in recent years. The online monitoring of formaldehyde concentration of the indoor environment has become an urgent issue in modern society. In this work, an ultrafast and highly selective room-temperature formaldehyde gas sensor based on the semiconductor nanomaterials was developed. The Pt-decorated MoO 3 nanobelts were employed as the formaldehyde sensing materials, which were synthesized through hydrothermal and chemical reduction process. The results show that the Pt nanoparticles loading on the surface of the nanobelts are metallic and well crystalized. After the surface-decoration by Pt nanoparticles, the room-temperature HCHO sensing performance of the MoO 3 nanobelts could be greatly enhanced. With only 0.61% (atomic ratio) of Pt nanoparticles loading on MoO 3 , the sensor response towards 200 ppm of HCHO could be increased from 5.7% to 39.3%. The average response and recovery rate were also improved, leading to ultrafast response and recovery process at room temperature. At the LOD (limit of detection) of 1 ppm, the response and recover time of the sensor was only 8.8 s and 0.94 s, respectively. Furthermore, the Pt-decorated MoO 3 nanobelts also exhibited outstanding selectivity against other typical interference VOC including methylbenzene, methanol, ethanol and acetone, as well as good anti-interference performance towards water vapors. The great improvement of the sensor performance could be attributed to the spill-over and catalytic effect of Pt nanoparticles toward HCHO at room temperature. • MoO 3 nanobelts synthesized by hydrothermal method were decorated by Pt nanoparticles. • The sample exhibits outstanding room-temperature HCHO response at room temperature. • The LOD was down to 1 ppm, with 8.8 s and 0.94 s as response and recovery time. • The sample exhibited high selectivity against other interference VOC gas. [ABSTRACT FROM AUTHOR]

Abstract In this paper, we report the effect of carbon encapsulation on the magnetic behavior of magnetite (Fe 3 O 4) nanoparticles obtained through chemical coprecipitation. Using starch, Fe 3 O 4 /carbon core–shell nanoparticles were produced through a hydrothermal method. Magnetic studies revealed that both the Fe 3 O 4 and Fe 3 O 4 /carbon core–shell nanoparticles were nearly superparamagnetic at room temperature; more importantly, carbon encapsulation significantly enhanced the room-temperature ferrimagnetism. Transmitting optical magnetic circular dichroism analysis indicated the existence of interfacial charge transfer in the Fe 3 O 4 /carbon heterosystem. The ferrimagnetic enhancement was attributed to the charge transfer to polarized states of the A- site in Fe 3 O 4 , which is equivalent to chemical reduction of the A- site irons of Fe 3 O 4. We concluded that Fe 3 O 4 /carbon core–shell nanoparticles formed a heterosystem so that the amorphous carbon passivated the magnetic semiconducting Fe 3 O 4 nanoparticles, to which the sp 2 electron was transferred. Highlights • Room-temperature ferrimagnetic enhancement was observed for carbon-encapsulated magnetite NPs. • Process temperature and the amount of starch precursor used in coprecipitation process was found to be crucial. • VSM and OMCD measurement have revealed interfacial charger transfer engendered the magnetic enhancement. • Chemical reduction of the A-site irons of Fe 3 O 4 caused by carbon-encapsulation was attributed to the observed magnetic enhancement. [ABSTRACT FROM AUTHOR]

Abstract High productivity and bath stability of electrodeposition for Al and its alloys from a dimethylsulfone (DMSO 2)-aluminum chloride bath are highly desirable characteristics for a wide range of critical applications. However, a long-standing problem for such electrodeposits is S and Cl contamination, which results in limited ductility. In this study, we explored a reduction method for S and Cl in Al electrodeposits from a DMSO 2 bath to facilitate plastic elongation of the electrodeposited Al. For 2–5:10 M ratios of aluminum chloride to DMSO 2 , tailoring the conditions of electrodeposition decreased the S and Cl contents to ∼0.2 at%. The addition of various metal salts revealed that gallium chloride further reduced the S and Cl contents to less than 0.1 at%. This reduction permitted the electrodeposited Al–Ga alloys to exhibit plastic elongation in tensile tests. Based on the results of experiments and first-principles calculations, we discuss the role of Ga in the growth mode of electrodeposits and its effect on grain boundary cohesion. Thus, we elucidate the mechanisms for realizing high strength and ductility in electrodeposited Al alloys. Highlights • Al electrodeposition from a DMSO 2 -based bath was conducted. • Adjusting deposition conditions reduced the total contents of S and Cl to ∼0.4 at%. • The addition of GaCl 3 reduced the total S and Cl contents to less than 0.1 at%. • Electrodeposited Al-Ga alloys exhibited plastic elongation in tensile tests. • The role of Ga in growth modes and its effects on GB cohesion were discussed. [ABSTRACT FROM AUTHOR]

Abstract This work focuses on the recovery of valuable metal from the cathode materials of spent lithium ion batteries to ensure resource recycling and environmental protection. An environmentally friendly process involving reduction roasting and stepwise leaching is proposed to recover Li and Ni, Co, and Mn from spent LiNi x Co y Mn 1-x-y O 2 materials. Suitable leaching conditions are obtained from thermodynamic analysis (Eh-pH diagram). The effects of several factors, such as acid concentration, temperature, leaching time and liquid‒solid ratio, on the leaching efficiency of valuable metals are investigated. Under optimum conditions, the leaching efficiency of Li, Ni, Co, and Mn are as high as 93.68%, 99.56%, 99.87%, and 99.9%, respectively. The kinetic aspect of the acid leaching process is analyzed by shrinking the core model, which suggests a residue layer diffusion process. The reaction activation energies of Ni, Co, and Mn are 29.35 kJ mol−1, 24.00 kJ mol−1, and 23.29 kJ mol−1, respectively. This metallurgic method contributes to environmentally friendly and economical recovery of valuable metals from spent lithium-ion batteries. Highlights • A novel metallurgical method is proposed to recycling spent LiNi x Co y Mn 1-x-y O 2. • The leaching conditions are comprehensively investigated and optimized. • The kinetics and the controlled step of acid leaching process are analyzed. • The active energies of Ni, Co and Mn reacting with H 2 SO 4 are calculated. [ABSTRACT FROM AUTHOR]

Abstract The hot compression tests for spray deposited alloy 2195 were performed on Gleeble-1500 thermomechanical simulator at different conditions. The constitutive models and processing map of the alloy were established. The deformation mechanisms at different areas of the processing map were revealed via metallographic and electron backscatter diffraction examinations of the compressed samples. The results showed that dynamic precipitation of Al 2 CuLi phase occurred at low deformation temperatures (400–450 °C). The precipitation caused significant reduction in solution strengthening effect, resulting in rapid decrease of flow stress. The instability domain at low temperature was induced by the decreasing flow stress. Moreover, the stacking faults with the precipitation of Al 2 CuLi caused the discontinuous dynamic recrystallization. The precipitation and recrystallization led to the high dissipation efficiency at low temperature and low strain rate. At high temperatures (500–550 °C), the deformation mechanisms varied with the imposed strain rates. The dynamic recovery and recrystallization occurred at strain rate of 0.1–1 s−1, which led to the high dissipation efficiency. At low strain rate (0.01–0.1 s−1), the alloy exhibited strong dynamic recovery characteristic, which caused the decrease in dissipation efficiency. The deformation instability occurred when the strain rate is about 10 s−1, and intergranular cracking was the main instability mechanism. Graphical abstract Image 1 Highlights • Arrhenius-type constitutive equation of spray deposited 2195 alloy was established. • Processing maps with different strain levels were constructed. • The precipitation of Al 2 CuLi occurred at low temperature, causing many changes. • Strong DRV causes decrease of efficiency η at high temperature and low strain rate. • The available hot working window of the deposited alloy 2195 was obtained. [ABSTRACT FROM AUTHOR]

Abstract To obtain high efficient and lightweight microwave (MW) absorption material, a novel composite RGO/PANI/BaNd 0.2 Sm 0.2 Fe 11.6 O 19 (BNSF) was successfully synthesized. The RGO/PANI composite was synthesized by an in-situ polymerization, the BNSF was obtained via a chemical co-precipitation method and the RGO/PANI/BNSF ternary nanocomposite was fabricated through high energy ball mill. The phase composition, microstructure and MW absorption performance of samples were investigated and discussed. The results exhibited not only an excellent composite structure, but also an outstanding MW absorption performance. The RGO/PANI/BNSF nanocomposites exhibited excellent MW absorption property with 30 wt.% of BNSF, the minimum reflection loss (RL) could reach −50.5 dB at 13.68 GHz with the thickness of 2.90 mm. Meanwhile, the introduction of multiple polarization and relaxation in ternary composite were responsible for the enhancement of microwave attenuation and a broad effective absorption bandwidth (6.8 GHz). Based on the above results, we confirmed that the RGO/PANI/BNSF composite will have a considerable prospect in the electromagnetic interference shielding field. Highlights • A novel kind of ternary nanocomposites was prepared. • The microwave absorption mechanism of ternary nanocomposites was discussed. • The ternary nanocomposites possessed excellent microwave absorption properties. [ABSTRACT FROM AUTHOR]

Abstract In this study, we prepared double loss Ti 3 SiC 2 /Co 3 Fe 7 powders by carbothermic reduction process at different temperatures. The powders were characterized and the electromagnetic wave absorption properties were investigated. As the carbothermic reduction temperature increased from 800 °C to 1000 °C, the intensities of diffraction peaks for Co 3 Fe 7 increased and the particles grew up. For the Ti 3 SiC 2 /Co 3 Fe 7 powders, the complex permittivity also increased but the complex permeability decreased with the rising temperature. The Ti 3 SiC 2 /Co 3 Fe 7 powders synthesized at 900 °C owned the most favorable microwave absorption performance. For the sample in 2.4 mm thickness, an effective absorption bandwidth could be obtained in the frequency range from 8.79 to 11.92GHzwith a minimum reflection loss value of −31.2 dB at 10 GHz. Considering the excellent chemical stability and microwave absorption performance, the Ti 3 SiC 2 /Co 3 Fe 7 powders could be used as a promising absorbent for high temperature application. Highlights • Co 3 Fe 7 powders with different particle sizes were synthesized at 800–1000 °C. • The powders synthesized at 800–1000 °C own different electromagnetic parameters. • The microwave absorption properties of Ti 3 SiC 2 /Co 3 Fe 7 powders were optimized. • This study contributes to exploring absorbents for high temperature application. [ABSTRACT FROM AUTHOR]

Abstract Aluminothermic reduction of ZrSiO 4 in the presence of carbon was investigated in the SHS (self-propagating high-temperature synthesis) manner. PTFE was employed not only as a reaction promoter to ensure self-sustaining combustion and improve the reduction of ZrSiO 4 , but as a carburizing agent to take part in carbide formation. The combustion wave velocity and temperature increased with increasing PTFE content, but decreased with carbon. Based on a correlation between combustion temperature and velocity, the activation energy E a = 180.4 kJ/mol was deduced for the PTFE-activated ZrSiO 4 /Al/C reaction. According to the XRD and EDS analyses, the phase composition of the synthesized product depended on the total amount of carbon. The SHS reaction produced Al 2 O 3 -added Zr-silicides (ZrSi 2 and ZrSi)/carbides (ZrC and SiC) composites. With an increase in carbon, the dominate phase was transferred from silicides to carbides. A further increase in carbon led to in situ formation of the ZrC/SiC/Al 2 O 3 composite. The study confirmed ZrSiO 4 as a source for the production of zirconium silicides, ZrC, and SiC. Highlights • ZrSiO 4 /Al/C solid state reaction produced in situ silicide/carbide composites. • ZrSiO 4 served as a source for formation of zirconium silicides, ZrC, and SiC. • PTFE activated reduction of ZrSiO 4 by Al in the self-sustaining combustion mode. • The activation energy of 180.4 kJ/mol was deduced for the ZrSiO 4 /Al/C reaction. [ABSTRACT FROM AUTHOR]

Abstract In recent years, heteroatom-doped biomass-derived carbon has attracted intensive attention in vast fields due to their inexpensive precursors and abundant resources, especially in oxygen reduction reaction and supercapacitors. This research demonstrates a simple strategy to prepare mulberry leaves-derived nitrogen, sulfur dual-doped ladder-like porous carbon material, which possesses high content of nitrogen (8.17 at %), sulfur (1.97 at %), large surface area (1689 m2 g−1) and porous structure with a mass of micropores and mesopores. With respect to electrode material of supercapacitor, the nitrogen, sulfur dual-doped ladder-like carbon exhibits large specific capacitance of 243.4 F g−1 at 0.1 A g−1 and outstanding durability (94% retention after 5000 cycles at 3 A g−1). Moreover, in comparison to Pt/C catalyst, nitrogen, sulfur dual-doped ladder-like porous carbon presents excellent electrochemical performances of long term stability (90.2% retention after 20000 s) and resistance to methanol crossover for oxygen reduction reaction. This work successfully may provide a new case to take advantage of nature materials to fabricate heteroatom-doped carbon for energy conversion and storage. Highlights • Mulberry leaves are used to prepare bifunctional carbon materials. • A unique ladder-like porous carbon is obtained for the first time. • The N,S doped porous carbon exhibits outstanding durability for SC. • The N,S doped porous carbon presents excellent long stability for ORR. [ABSTRACT FROM AUTHOR]

Abstract ZrB 2 -ZrC composite nanofibers were fabricated by electrospinning and carbothermal reduction. The morphology, phase composition and interface were characterized. The fabricated ZrB 2 -ZrC composite nanofibers are uniform and the diameter is about 100 nm. The effects of heat-treatment temperature, n(B)/n(Zr) and n(C)/n(Zr) on the microstructure and phase composition of composite nanofibers were systematically investigated. The results shows heat-treatment temperature has influence on the phase composition and grain size of the ZrB 2 -ZrC composite nanofibers. The content of ZrC in the ZrB 2 -ZrC composite nanofibers can be adjusted by the value of n(B)/n(Zr) in the precursors. As n(B)/n(Zr) equal to 3.5, the mass ratio between ZrB 2 and ZrC is about 48:52 which is very close to the eutectic composition of ZrB 2 -ZrC composites. The value of n(C)/n(Zr) also affects the phase composition of composite nanofibers. Reaction process and phase evolution during heat-treatment were studied based on analysis of reaction thermodynamics. The value of n(B)/n(Zr) influences the phase evolution during fabrication of ZrB 2 -ZrC composite nanofibers. The tensile mechanical properties were tested, indicating that the addition of ZrC has the ability to improve the plasticity of ZrB 2. Highlights • ZrB 2 -ZrC composite nanofibers with different ZrC content are fabricated. • ZrC content in the composite nanofibers can be adjusted by n(B)/n(Zr). • Reaction process and phase evolution were studied based on reaction thermodynamics. • Addition of ZrC has the ability of improve the plasticity of ZrB 2. [ABSTRACT FROM AUTHOR]

Abstract In this work, for the first time, a grafting of 3-aminopropyltriethoxysilane (APTES) followed by incorporation of iron nanoparticles (Fe-NPs) was used for the functionalization of graphene oxide (GO). Changes in stability, structural, morphological, thermal and catalytic properties of the resulting GO/APTES/Fe material were investigated by scanning electron microscopy, transmission electron microscopy, energy dispersive X-Ray, Fourier transform infrared and UV–visible spectroscopies, zeta potential measurements, X-ray photoelectron spectroscopy and differential scanning calorimetry. The average crystallite size of GO/APTES/Fe was found to decrease significantly after the post treatment, producing slight structure compaction. Iron nanoparticles were immobilized by APTES on the GO sheets, with a particle size around 50 nm. Fe insertion and APTES grafting resulted in high thermal stability of GO. As an application, GO/APTES/Fe exhibited an excellent catalytic activity in the reduction of 4-nitrophenol into 4-aminophenol. The presence of both APTES and small amount of Fe nanoparticles in GO/APTES/Fe induced a significant improvement in catalytic activity. GO/APTES/Fe also showed appreciable recyclability after four repeated uses without noticeable loss in activity. This stability was higher to those of other GO-materials. The results obtained herein open new prospects for Fe-loaded organo-graphene oxide as efficient material in catalysis and industrial applications. Highlights • A novel GO/APTES/Fe as metal-organic-graphene-oxide was prepared firstly. • GO/APTES/Fe exhibited excellent catalytic activity toward the reduction of 4-NP as hazardous pollutant. • Iron nanoparticles were stabilized by APTES within the GO sheets. • The electron transfer between Fe-NPs and GO/APTES contributes to the strong adsorption of negatively-charged reactants. • An excellent new catalyst for the reduction of 4-nitrophenol with recyclability. [ABSTRACT FROM AUTHOR]

Abstract Silicon carbide is widely used as ultra high-temperature ceramics, semiconductors, and pressure sensors with promising potentials for high-temperature, high-endurance, and radiation hardened applications. Daunting difficulties in experimental investigations of thermophysical properties hinder the better understanding of high-temperature material behaviors of silicon carbide. We present a comprehensive study of temperature-dependent mechanical and thermodynamic properties of SiC polytypes by first-principles methods. The obvious anisotropy of linear expansion and elasticity is found for 3C-SiC, while it is not distinct for other non-cubic SiC polytypes. Results show that the temperature dependences of mechanical properties exhibit the softening behavior, in which small linear reduction (∼4.4%) in Vickers hardness and shear modulus but large linear reduction (∼7.0%) in Young's modulus are detected. The heat-resistant properties of SiC polytypes are ranked as 3C-SiC < 4H-SiC < 6H-SiC < 15R-SiC < 2H-SiC. The present predictions are in favorable accord with available measured data in the literature. Highlights • The thermophysical properties of SiC polytypes are predicted by first principles. • SiC polytypes exhibit the varying degrees of softening of mechanical properties. • The heat-resistant capacity of SiC polytypes are ranked as 3C < 4H < 6H < 15R < 2H. • This study lays the foundation for high-temperature behaviors of silicon carbides. [ABSTRACT FROM AUTHOR]

Co 3 O 4 nanoplates/reduced graphene oxide (CGP) composite was synthesized through a facile hydrothermal method followed by thermal treatment. The obtained CGP composite exhibits a superior electrochemical performance as an anode for lithium ion batteries, especially after 150 discharge/charge cycles. Characterization of the microscopic features suggests that the structure of the Co 3 O 4 nanoplates gradually evolves during cycling due to the electrochemical reconstruction process, transforming into an integrated architecture assembled by nanoparticles with thicknesses of tens of nanometers. The as-formed integrated nanostructure can reduce the stress caused by volume variations during cycling, provide short diffusion path lengths for Li ions and electrons, and offer good electrode conductivity to improve the reaction kinetics, which will tremendously enhance the electrochemical performance of the CGP electrode in lithium ion batteries. [ABSTRACT FROM AUTHOR]

Cobalt sulfide is a promising anode material for a sodium-ion battery because of its high capacity and abundance. However, practical issues such as huge volume changes during sodiation/desodiation result in a low capacity retention during cycling, thus posing a serious challenge to practical applications. In this work, we report a rather easy, single pot microwave synthesis technique having the ability to create carbon-coated, uniformly distributed cobalt sulfide nanoparticles (20–40 nm) on reduced graphene oxide (CoS 2 @C-rGO). In this structure, the graphene substrate acts as a robust conductive platform to anchor cobalt sulfide, and the outer carbon encapsulation guarantees both the structural integrity and conductivity of the composite. When evaluated as an anode material in a sodium-ion battery, CoS 2 @CrGO exhibited a stable cycling performance and superior high-rate capability, delivering a reversible capacity as high as 794.9 mAhg −1 at 0.5 A, after 175 cycles. Furthermore, our CoS 2 @C-rGO electrodes can be used as enzyme-less glucose sensors that exhibit a wide linear response within a range of up to 3 mM of glucose and a low detection limit of 0.078 M. [ABSTRACT FROM AUTHOR]

The design of semiconductor-based heterojunctions is an effective strategy to build highly active photocatalyst systems. In this study, tungsten disulfide (WS 2) modified graphitic carbon nitride (gCN) heterojunction (gCN/WS 2) is incorporated with Co and Ni (gCN/WS 2 -Co and gCN/WS 2 -Ni) to enhance the photocatalytic hydrogen evolution reaction (HER) activity of gCN/WS 2 via performing a chemical reduction method and characterized by advanced analytical techniques. The photocatalytic HER activities of gCN, gCN/WS 2 , gCN/WS 2 -Ni and gCN/WS 2 -Co were measured as 0.126, 0.221, 0.237 and 0.249 mmol g−1h−1, respectively, under the visible light irradiation. The improvement of photocatalytic activity and stability of gCN/WS 2 -Ni and gCN/WS 2 -Co nanocomposites could be attributed to the 2D/2D heterojunction structure, extended light harvesting ability, increased electron-hole lifetime and decreased recombination rate of the charge carriers. Moreover, mechanistic studies revealed that a S-scheme heterojunction is attributed to the enhanced photocatalytic HER by the gCN/WS 2 -Ni and gCN/WS 2 -Co photocatalysts, which provides promoted efficiency by photocarrier transfer and separation. [Display omitted] • gCN/WS 2 -Y (Y: Ni, Co) heterojunctions are prepared by chemical reduction method. • gCN/WS 2 -Y enhance the photocatalytic HER activity compared to gCN, WS 2 and gCN/WS 2. • Performance of gCN/WS 2 -Y photocatalysts is investigated in HER. • Transition metal doped heterojunction shows increased activity and stability. • Type-II heterojunction enhances efficiency by photocarrier transfer and separation. [ABSTRACT FROM AUTHOR]

Herein, we report the synthesis of bimetallic Au-Pd and monometallic Au and Pd nanoparticles (NPs) by successive reduction of the respective metal ions using phytochemicals in the form of plant extract under ambient conditions. Phytochemicals act both as reducing and shape directing agent for metal and alloy NPs. The synthesized nanostructures were characterized by different microscopic, spectroscopic and diffractometric techniques. Microscopic results confirmed that the shape and size of the alloy nanostructures can be tuned by varying the concentration ratio of metal ions in the reaction medium. Energy dispersive X-ray and X-ray photoelectron spectroscopic analysis confirmed the formation of bimetallic Au-Pd nanostructures. The purity and crystalline properties were studied by X-ray diffraction technique. UV–vis spectra were recorded to study the optical properties of the synthesized nanostructures. Further, we tested the catalytic activity of both the monometallic and bimetallic alloy nanostructures in borohydride reduction of hazardous organic dye molecules in aqueous medium. The bimetallic alloy NPs exhibit better catalytic activities compared to their respective monometallic nanoparticles. [ABSTRACT FROM AUTHOR]

In their operating environments, turbine blades usually suffer from microstructural degradation and a corresponding reduction in mechanical performance. Load-free and load-assisted experiments were conducted to determine the microstructural degradation kinetics of a directionally solidified (DS) Ni-based superalloy, DZ125, commonly applied as a first-stage blade material in aero-engines. The results show that a transition time from the linear law to the power law exists during isotropic coarsening in load-free testing. The directional coarsening behaviour of DZ125 under load-assisted intensifies with the increase in exposure temperature and applied stress. A unified analytical model for γ′ precipitate evolution of DZ125 superalloys, based on Lifshitz-Slyozov-Wagner (LSW) theory, was proposed to predict the experimentally observed increase in the coarsening extent associated with increase in temperature, time, and applied stress. Microstructural information, such as γ′ precipitate width and channel width in modelling work, was extracted using the cross-correlation analysis algorithm . The model can accurately estimate the γ′ precipitate evolution of DS DZ125 superalloys. In addition, based on the model, the analytical process derived for evaluating the service temperature and stress field of turbine blades was verified by data pertaining to the trailing edge of a turbine blade. [ABSTRACT FROM AUTHOR]

There is a growing need to lower the band gap of the transparent conductive tin oxide (SnO 2 ) in view of its potential application in photo-electronic technology. Here, we systematically investigated the effect of Pb doping on lowering the band gap of SnO 2 . We demonstrate a significant reduction in its band gap to as much as ∼0.8 eV (3.64 eV–2.87 eV) upon 15% Pb doping. The observed band gap tunability with Pb-incorporation provides a direct and efficient approach to effectively tailor the band gap and is expected to open up applications in emerging oxide opto-electronic and energy applications. [ABSTRACT FROM AUTHOR]

The silver loaded adsorbents has been demonstrated to be an exciting approach towards Hg 0 removal from natural gas streams, its Hg 0 removal efficiency and capacity is closely related to the valence state, particle size and dispersity of silver particles. This study focused on chemical reduction methods in aqueous solutions to synthesize Ag/4A zeolite, and the influences of ultrasonic and protective additives were investigated to reduce the size of silver particles. The characterization results showed that silver particles are loaded on the surface of 4A zeolite with highly dispersed elemental form, ultrasonic and addition of stearic acid as protective additives are the effective ways to produce small nano-scale silver particles close to 15 nm. Meanwhile, the silver particles on the surface of Ag/4A zeolite are the active sites for Hg 0 adsorption which can react with Hg 0 to form Ag-Hg amalgam alloy. The silver lattices disappeared from the outer boundary to the interior of the particles after Hg 0 adsorption, which indicated that the Hg 0 firstly reacts with the nano-scale silver on the surfaces and then gradually penetrates into the interior of silver particles. The Hg 0 removal efficiency of prepared Ag/4A zeolite adsorbents was higher than 96% after 200 min adsorption at 30 °C, and adsorption capacity reached to 5.985 mg/g. Furthermore, the regeneration and reutilization results indicated that the Hg 0 adsorption performance remained stable after 5 reuse cycles. [ABSTRACT FROM AUTHOR]

The electrodeposition of Fe-Mo alloys from an alkaline solution containing sorbitol as the complexing agent for Fe(III) ions was studied. XRD analysis of the film produced by reduction of [MoO 4 ] 2- anions at a copper substrate showed the formation of MoO 2 . The presence of the intermediate Fe(II) species was detected by electrolysis from an Fe-Mo solution and Visible spectroscopy of the final solution in the presence of 1,10-phenanthroline. The Visible spectrum showed a broad absorption ( λ max  = 514 nm) typical of the [Fe(phen) 3 ] 2+ complex. Under our conditions, the Fe-Mo alloy was formed from reduction of [Fe(OH) 2 (C 6 H 12 O 6 ) 2 ] 3- to [Fe(OH) 2 (C 6 H 12 O 6 ) 2 ] 4- , reduction of [MoO 4 ] 2- to molybdenum (IV) oxide/hydroxide and its further reduction to Mo 0 concomitant with [Fe(OH) 2 (C 6 H 12 O 6 ) 2 ] 4− ads to Fe 0 . Photomicrographs of the Fe-Mo electrodeposits produced with q d 5.30Ccm −2 showed that they were smooth or contained cracks, depending on the deposition potential (E d ). Chemical composition analysis by EDXS of Fe-Mo electrodeposits (q d 5.30Ccm −2 ) showed that deposits containing 5.5 at% (18.8 wt%) Mo could be produced at E d −1.40 V and similar values were obtained at more negative potentials. X-Ray diffraction indicated that the Fe-Mo coatings were composed of Fe 3 Mo and Fe 2 MoO 4 phases, regardless of E d . The presence of the Fe 2 MoO 4 phase on the sample surface could explain the observation of Fe 2+ and Mo 4+ states by XPS, although the occurrence of others crystalline oxide phases, such as FeMoO 4 and Fe 2 (MoO 4 ) 3 could not be discarded. The crystal size value varied from ∼47 nm to ∼37 nm, when E d changed to more negative values. [ABSTRACT FROM AUTHOR]

Tungsten was added to Nb 40 Ti 30 Ni 30 alloys to investigate its effects on microstructure, hydrogen permeability and hydrogen absorption properties. Tungsten-added alloys consisted of a primary (Nb, Ti) phase and TiNi+(Nb, Ti) eutectic structure, although tungsten concentrated at the center of the primary phase. Tungsten addition did not change their hydrogen permeability. However, the hydrogen capacity decreased with increasing tungsten content, and 20% reduction of hydrogen capacity was attained by adding 5% tungsten. After annealing, tungsten was dissolved homogeneously in the primary phase, and segregation disappeared. The hydrogen permeability and capacity of the annealed alloy were 50% higher and 10% lower, respectively, than those of tungsten-free alloy. Thus, tungsten can reduce hydrogen capacity without degrading hydrogen permeability, which is expected to improve the resistance to hydrogen embrittlement. [ABSTRACT FROM AUTHOR]

Aluminum/graphene (Al/G) composites with enhanced heat-dissipation and mechanical properties were prepared by the powder metallurgy (P/M) technique. Graphene was first uniformly coated on the surface of micro-sized aluminum (Al) powders by an in-situ reduction reaction of GO and Al. Al/G bulk composites with uniform graphene dispersion in Al matrix were fabricated by the simple conventional P/M technique. Enhancements of 15.4% in thermal conductivity, 9.1% in specific heat capacity, 21.1% in hardness, and 25.6% in compressive strength were achieved with only 0.3 wt% graphene addition into pure Al. [ABSTRACT FROM AUTHOR]

In the process of beneficiating iron ores by the magnetic separation, particles of hematite and quartz accumulate, forming tailings that occupy large areas of agricultural lands. Such man-made deposits are quite common and contain large quantities of iron oxides such as hematite. Therefore the tailings can be used as raw material for the production of magnetite. In this work, magnetite was synthesized by hematite reduction at a temperature of 500 °C in an atmosphere of carbon monoxide. The source hematite was separated initially into ten particle size categories ranging from 0.05 to 2.5 mm. The reduction was carried out with carbon monoxide, which was synthesized by reaction of air and activated carbon at 750 °C. It was determined by X-ray diffraction analysis and magnetometry that, after reduction, samples of each particle size consisted mainly of magnetite. In addition, the magnetic properties of the resulting magnetite were noted to be somewhat different from those of natural magnetite. In particular, remanence and coercivity are higher for synthetic magnetite than for natural magnetite. The saturation magnetization of transformed samples increases to 60–80 Am 2 /kg, while the source hematite does not have strong magnetic properties. Hematite with a particle size from 0.05 to 0.25 mm is completely converted into magnetite, but if the size of hematite particles increases to from 0.25 to 2.5 mm, incomplete conversion of hematite to magnetite is observed. The obtained results are important for the development of technology for converting hematite to magnetite, which can, in turn, be used to beneficiate iron ores. [ABSTRACT FROM AUTHOR]

Cobalt doped Pr 0.5 Ba 0.5 FeO 3-δ perovskite exhibits superior electrochemical performance when it was tested as an anode for intermediate temperature solid oxide fuel cell. For the anode with a composition of Pr 0.5 Ba 0.5 Co 0.25 Fe 0.75 O 3-δ –Ce 0.9 Gd 0.1 O 2-δ , the polarization resistance R p was as low as 0.05 Ωcm 2 at 700 °C in air and 0.21 Ωcm 2 at 700 °C in 3% H 2 O–97% H 2 . In addition, this full-ceramic anode was tolerant to 50 ppm H 2 S and showed stable performance during the preliminary test. The ceramic composite also exhibited superior activity for cathodic oxygen-reduction-reaction (ORR), thus enabled a symmetrical fuel cell. In a lab designed full-ceramic symmetrical fuel cell, a power density of 0.75 Wcm −2 at 750 °C has been achieved, demonstrating the superior properties of this oxide. [ABSTRACT FROM AUTHOR]

The kinetics of reduction raw and pre-oxidized ironsand with hydrogen was studied using a combination of thermogravimetric analysis technique and microstructural characterization. Temperature range of 1073–1273 K (800–1000 °C) and H 2 partial pressure of 0.1–1.0 atm were covered. It was found that the reaction is first order with respect to p H2 at 1173 K (900 °C). The reduction reaction was considerably faster for the pre-oxidized ironsand, owing to the presence of micro-cracks in the particles. The extent of reduction was quantified against time at different temperatures and the results were analyzed using both conventional kinetic models, as well as an iso-conversional method. The results indicated that for the raw ironsand, the reduction rate is first limited by nucleation and growth of products and later by first order chemical reaction. At last, it is controlled by three-dimensional diffusion of reactants. The apparent activation energy of reduction increased from ∼50 to 105 kJ mol −1 when the conversion degree increased from 0.2 to 0.6. On the other hand, the activation energy for the pre-oxidized ironsand remained stable at 67.2 kJ mol −1 over the entire process, following a first order chemical reaction control step. The diffusion-limited step does not appear to be limiting the rate for the pre-oxidized ironsand reduction process due to the micro-cracks formed in this material, facilitating the gas access to solids. [ABSTRACT FROM AUTHOR]

Conformal magnetite nanoparticles are successfully prepared by one-step reduction method in the autoclave with controlled reduction conditions. The x-ray diffraction pattern indicates pure phase of Fe 3 O 4 nanoparticles with high crystallinity were obtained. TEM analysis shows the presence of spherical nanoparticles with homogeneous size distribution of ∼20 nm. The obtained Fe 3 O 4 nanoparticles have high saturation magnetization Ms of 75.3 emu·g −1 . The inverse spinel Fe 3 O 4 phase displays a distinct ferrimagnetic anisotropy. The Verwey metal-insulator transition of magnetite nanoparticles usually takes place at the blocking temperature of 120 K. The one-step reduction method in the autoclave of magnetite with well-controlled phase and high saturation magnetization in this work provides a promising opportunity for the synthesis of magnetic nano-materials to be used in wastewater treatment, catalyst, lithium-ion battery, contrast imaging, and especially in bio-applications. [ABSTRACT FROM AUTHOR]

Low-cost metallic nanoparticles as catalysts with good performance are highly desired for the development of hydrogen storage materials. In this work, ceria-doped CuNi nanoparticles were successfully immobilized on the surfaces of reduced graphene oxide (rGO) by a simple co-reduction approach in aqueous solution at room temperature, characterized by ICP-OES, XRD, TEM, SEM-EDS and XPS techniques. The as-synthesized CuNi-CeO 2 /rGO nanocomposites with various metal contents had been employed as heterogeneous catalysts for the hydrolytic dehydrogenation of ammonia borane (NH 3 BH 3 , AB) under mild conditions. The optimal catalyst of Cu 0.8 Ni 0.2 -CeO 2 /rGO with CeO 2 content of 13.9 mol% exhibited an excellent catalytic activity with the exceedingly high TOF value of 34.4·mol H2 ·mol catalyst −1 ·min −1 at 298 K. The apparent activation energy was calculated to be 19.1 kJ mol −1 , even lower than most of noble-metal-based catalysts for AB dehydrogenation. The detailed kinetics of AB hydrolysis catalyzed by Cu 0.8 Ni 0.2 -CeO 2 /rGO had been investigated on different concentrations of catalyst, substrate and temperatures. Moreover, the obtained in situ hydrogen from AB hydrolysis can be further applied to reduce 4-nitrophenol with a high TOF value of 8.1 min −1 at room temperature. The high catalytic activity of Cu 0.8 Ni 0.2 -CeO 2 /rGO would be contributed to the small size of CuNi-CeO 2 NPs, metal-metal synergy, and the metal-support interaction. [ABSTRACT FROM AUTHOR]

Sodium-ion batteries (SIBs) are highly attractive electrochemical devices for massive energy storage because of their low cost and abundance of sodium, but insufficient anode performance remains a key challenge for the commercialization of this attractive technology. In this study, a hierarchically porous CoS 2 /graphene composite with an architecture of CoS 2 nanoparticles embedded in reduced graphene oxide (rGO) is synthesized through a one-step hydrothermal route allowing the growth of the CoS 2 phase and the reduction of the graphene oxide simultaneously. This composite is applied as an anode material for SIBs, delivering favorable performance. The CoS 2 phase consists of nanoparticles of ∼10 nm that are uniformly anchored on the rGO, forming a CoS 2 /rGO hybrid with strong phase interaction. As a conversion-type anode for SIBs, the electrochemical testing results show significantly enhanced sodium-storage properties for the CoS 2 /rGO composite compared with that of bare CoS 2 . Impressively, the CoS 2 /rGO nanostructure exhibits a high discharge capacity of approximately 400 mAh g −1 after 100 cycles at specific current of 100 mA g −1 , corresponding to approximately 80% of the discharge capacity in the second cycle. Such improvement may be due to the two-dimensional conductive network, homogeneous dispersion and immobilization of the CoS 2 nanoparticles, as well as the enhanced wettability of the active material in the electrolyte by introducing rGO. The results suggest that this well-designed conversion-type CoS 2 is a promising anode material for high-performance SIBs. [ABSTRACT FROM AUTHOR]

For the improvement of the properties of cemented carbides, ultra-fine spherical cobalt powders as binder were prepared using calcium cobaltite. The effects of the ratio of CaO to CoO, the calcination temperature and the reduction temperature on particle size and morphology of cobalt powders were studied. The results show that the average particle size of cobalt powders decreases with increasing the weight ratio of CaO to CoO, but increases with the calcination temperature and reduction temperature. The spherical cobalt powders with the mean particle size of 84 nm are obtained when the weight ratio of CaO to CoO is 7:4 and the calcination temperature and reduction temperature are 1000 °C and 700 °C, respectively. In addition, CaO regarded as the blocking agent can refine cobalt powders during the hydrogen reduction process. [ABSTRACT FROM AUTHOR]

Cobalt-based nanomaterials have received considerable attention in electric energy-storage devices due to their outstanding electrochemical characteristics. However, multiple time- and energy-consuming steps and complex reduction processes for producing cobalt and cobalt oxide nanostructures are disrupting their substantive commercialization. Here, we propose a facile, ultra-fast, and versatile method for the fabrication of cobalt and cobalt oxide nanostructures using an intense pulsed white light (IPWL) photothermal reduction technique. The mechanism of the IPWL photothermal reduction of cobalt and cobalt oxide is firstly studied by measuring the in-situ temperature of the Co(NO 3 ) 2 -coated carbon fiber paper (CFP) substrate during IPWL irradiation and analyzing the crystal structures of the IPWL-irradiated samples. Cobalt nanoflakes and cobalt oxide nanoparticles are synthesized on the surface of the CFP substrate by irradiating IPWL for 10 ms at ambient temperature and pressure with various energy densities from 10 to 30 J cm −2 . The Co 3 O 4 nanoparticle/CFP and Co nanoflake/CFP samples are further utilized as an electrode, and each electrode exhibits high specific capacity of 29 and 73 mA h g −1 , respectively, at a current density of 1 A g −1 . Since this novel photothermal reduction technique is applicable to other transition metals and metal oxides, it is a promising method for not only energy storage systems, but also for energy generation applications, filters, sensors, and catalysis systems. [ABSTRACT FROM AUTHOR]

In air atmosphere, the spontaneous reduction abilities of Sm 3+ →Sm 2+ in Sm ions doped monoclinic SrAl 2 Si 2 O 8 (SASO) and BaAl 2 Si 2 O 8 (M-BASO) as well as hexagonal BaAl 2 Si 2 O 8 (H-BASO) are investigated. Sm ions doped MAl 2 Si 2 O 8 (M = Sr, Ba) samples were synthesized using Pechini-type sol-gel technology and sintered in air atmosphere and reducing condition, respectively. By comparing the photoluminescence properties of Sm doped MAl 2 Si 2 O 8 (M = Sr, Ba) calcined in air with that in reducing condition, the spontaneous reduction of Sm 3+ →Sm 2+ can be detected only in the host lattice H-BASO. The essential that makes the reduction of Sm 3+ to Sm 2+ was investigated by calculating their chemical bonds parameter quantitatively. The important key environmental factor of Ba 2+ in H-BASO is the largest among the three samples MAl 2 Si 2 O 8 . It indicates that the hexagonal H-BASO sample is the easiest one to realize the spontaneous reduction of Sm 3+ →Sm 2+ among Sm doped MAl 2 Si 2 O 8 (M = Sr, Ba) samples. The needed energy transferring one electron of the ligand to the central ions Sm 3+ in H-BASO:Sm is the lowest. The theoretical analysis agrees well with the experimental result. Our work provides with the theoretical and experimental foundation for the spontaneous reduction of trivalent samarium in the crystals. [ABSTRACT FROM AUTHOR]

Low working temperature and high sensitivity of gas sensors are critical in their practical applications; however, these properties are usually contradictory and cannot be realized simultaneously. Here, ZnO porous nanowires (PNWs) are prepared by a modified electrospinning method, and Pt nanoparticles (NPs) are doped on their surface by chemical reduction. The effects on morphology, specific surface area, and oxygen vacancy are discussed for the acetone gas-sensing performance. Results showed that Pt-ZnO PNWs responded optimally to acetone gas at 160 °C at 16.7–1.8 ppm, which was three-fold greater than that of pristine ZnO PNWs. In addition, the lowest detection limit is 50 ppb, a ten-fold lower level than pristine ZnO PNWs. The sensor exhibits superior acetone selectivity, humidity resistance, repeatability, long-time stability, noble metals, and a porous design with a large surface area, providing synergistic effects that increase the number of surface adsorption sites. Thus, the approach provided a new comprehension for loading a high-dispersibility catalyst onto the porous structure surface as a potential breath analyzer. [Display omitted] • Pt-ZnO with porous 1D nanowires morphology prepared by modified electrospinning. • The novel porous structure provided abundant active sites and diffusion channels. • Pt NPs doping induced more oxygen vacancy due to the catalytic action. • The Pt-ZnO PNWs sensor exhibited superior acetone sensing at low temperature. • The gas-sensing mechanism was expounded in detail. [ABSTRACT FROM AUTHOR]

We demonstrate the reduced graphene oxide (rGO) and comparison of Polymethylcarbazole (PMCz) and rGO/PMCz composites and their capacitive performances, which were calculated by cyclic voltammetry (CV), charge-discharge cycling and electrochemical impedance spectroscopy (EIS) in 1 M H 2 SO 4 solution. These active materials were characterized by Fourier-transform infrared spectroscopy-Attenuated transmission reflectance (FTIR-ATR), scanning electron microscopy (SEM), and energy-dispersive X-ray analysis (EDX), atomic force microscopy (AFM) and thermal gravimetric analysis (TGA). Supercapacitor device performances were taken by cyclic voltammetry (CV), galvanostatic constant current (CC), and electrochemical impedance spectroscopy (EIS) as two electrode configuration. According to galvanostatic charge/discharge analysis, rGO/PMCz composite represents specific capacitance (C sp ) of 526.84 Fg −1 which is higher than that of PMCz (350.00 Fg −1 ) and rGO (359.06 Fg −1 ) at current density of 10 mA in 1 M H 2 SO 4 solution. rGO/PMCz electrodes have great potential for practical applications in electrochemical capacitors. There is a positive improvement such as SEM-EDX, FTIR analysis and capacitance, energy and power densities for rGO/PMCz nanocomposite compared to PMCz. [ABSTRACT FROM AUTHOR]

One dimensional tin/indium (Sn/In) nanowires have been synthesized through a surfactant assisted chemical reduction method in aqueous solutions at low temperature (∼0 °C). Synthetic parameters such as stirring speed, injection rate of reducing agent, and alloy ratio were used to control the size and aspect ratio of the resulting nanowires. It was observed that the diameter of the nanowires was around 70 nm for all the synthesis conditions that were studied, whereas the length of the nanowires can be controlled in the range of 400 nm to 2 μm. The morphology and structure of the Sn/In nanowires were characterized by field-emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HRTEM), and X-ray powder diffraction (XRD), and their thermal properties were measured by differential scanning calorimetry (DSC). Structure analysis indicated that the Sn/In nanowires were mainly composed of InSn 4 and Sn; whereas no In 3 Sn phase was observed in the nanowires. DSC results confirmed the structures of the Sn/In nanowires that were measured through XRD and indicated that the nanowires started to melt at a relatively low temperature around 118 °C. Finally, a growth mechanism based on the reaction and structural evolution was proposed to explain the nanowire formation and growth process. [ABSTRACT FROM AUTHOR]

Porous magnetite nanoparticles have been successfully synthesized by a one-step reduction of waste ferrous sulfate with pyrite under nitrogen protection. In addition, the effect of calcination temperature, calcination time and the mass ratio of ferrous sulfate to pyrite on the particle size of porous magnetite nanoparticles were studied. The properties of magnetite nanoparticles synthesized were characterized via X-ray diffraction (XRD), Fourier transform infrared spectrum (FTIR), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), superconducting quantum interference device magnetometer (SQUIDM) and Brunauer–Emmett–Teller (BET) method. The formation of magnetite nanoparticles with inverse spinel structure was verified by XRD, FTIR and XPS. TEM micrograph suggested that the cubic magnetite nanoparticles with particle size of 25–50 nm were obtained. the surface area and the pore volume of magnetite nanoparticles were estimated to be 10.6 m 2 /g and 0.059 cm 3 /g. Magnetization hysteresis curve exhibited the values of coercivity and remanence and saturation magnetization were found to be approximately 0.09 kOe, 7.9 emu·g −1 and 77 emu·g −1 , respectively. [ABSTRACT FROM AUTHOR]

Poly ( p –phenylenediamine)–reduced graphene oxide/lithium titanate (P p PDA–RGO)/Li 4 Ti 5 O 12 (PG/LTO) nanocomposites were prepared by a simple one–step synthesis procedure using the redox reactions of a graphene oxide/LTO (GO/LTO) suspension and p –phenylenediamine ( p PDA). The effect of p PDA on both the reduction of GO and the electrochemical performance in a lithium battery anode was systematically evaluated at different p PDA loadings. The rate capabilities of the PG/LTO nanocomposites were found to be superior to those of both GO/LTO and pristine LTO. Optimum electrochemical performance was ultimately obtained with a p PDA:GO ratio of 3:1. The use of p PDA increased the reduction of GO/LTO and ensured good contact between the RGO and LTO, thereby increasing the electrical conductivity of the nanocomposites. [ABSTRACT FROM AUTHOR]

In this work, a facile one-step hydrothermal method has been developed for the fabrication of bismuth nanoparticles embedded carbon nanocomposites (Bi@Cs) with porous network structure. In this approach, natural polysaccharide alginate acts as both carbon source and reducing agent that can reduce Bi 3+ to form Bi nanoparticle. The Bi@Cs were characterized by X-ray diffraction, transmission electronic microscopy, energy dispersive X-ray spectrum, Fourier transform infrared spectroscopy, and Brunauer-Emmett-Teller analysis. The catalytic activity of the Bi@Cs for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with sodium borohydride was tracked by UV–visible spectroscopy. It was found that the Bi@Cs displayed high activity in the 4-NP reduction, which is superior to many noble metal nanoparticle supported catalysts. [ABSTRACT FROM AUTHOR]

Preparing coating material of welding electrode from ilmenite placer by carbothermic reduction with added ferrosilicon (Fe–Si) has been developed. The reduction behavior of ilmenite placer–coal–ferrosilicon mixture, as well as the phase composition and microstructure of reduced ilmenite were investigated by TG/DTG/DSG, XRD and SEM/EDS analysis, respectively. It is found that the carbothermic reduction of ilmenite placer can be enhanced by adding Fe-Si powder. A part of silicon in the Fe-Si acts as reductant to participate the reduction process. The heat released from the exothermal silicothermic reduction reactions increases the temperature in the neighboring area, facilitating the strong endothermic gasification reaction and finally accelerating the reduction rate. The results show that the addition of Fe-Si facilitates the nucleation and coalescence of metallic iron formed by reduction. [ABSTRACT FROM AUTHOR]

In this work, the behavior of the Fe@Pt core-shell particles and hollow Pt(Fe) particles during pressureless Spark Plasma Sintering (SPS) was investigated. The Fe@Pt core-shell microparticles were synthesized by galvanic replacement reaction using reduction of H 2 PtCl 6 aqueous solution by metallic iron. Pt(Fe) hollow particles were obtained by dissolving iron from the synthesized core-shell particles in HCl solution. Consolidation resulted in the formation of porous compacts, necking between the particles, alloying between the metals, and growth of the crystallites. The compositional design of the consolidated materials was possible through changing the order of sintering and HCl treatment stages. This work has demonstrated that acid corrosion and SPS can be used together to tailor the composition and morphology of materials derived from the core-shell particles. [ABSTRACT FROM AUTHOR]

Construction of metal oxide/sulfide and carbon-based material nanocomposites is an effective strategy to obtain high-performance electrode materials for supercapacitors. In the present work, graphene oxide nanofibers (GONFs) are selected as the support materials, and the nanocomposite of reduced graphene oxide nanofiber and cobalt sulfide (rGONF/CoS 2 ) is synthesized via a simple and facile method. As an electrode material for pseudocapacitors, the rGONF/CoS 2 nanocomposite exhibits a high specific capacitance of 635.8 F g -1 at a current density of 1 A g -1 measured in 6 M KOH electrolyte, which is much higher than that of bare cobalt sulfide. Furthermore, the rGONF/CoS 2 nanocomposite has also shown excellent cycling performance with 95.4% capacitance retention over 2000 cycles. In addition, the assembled asymmetric supercapacitor (ASC) device using rGONF/CoS 2 nanocomposite as cathode material and activated carbon (AC) as anode material can work at a high operating voltage of 1.65 V and show a maximum energy density of 13.8 W h kg −1 at a power density of 824.6 W kg −1 . [ABSTRACT FROM AUTHOR]

The gas-based isothermal reduction kinetics of oxidized vanadium titano-magnetite (VTM) under the range of 1173–1323 K was investigated in this study. The influence of reduction temperature, gas composition and reduction time on reduction process were studied. Experiment results display that the reduction degree of pellets significantly increases with increasing of reduction temperature, reduction time and ratio of H 2 /(CO + H 2 ). The kinetics study indicates that the early stage of gas-based reduction course is controlled by intrinsic chemical reaction and in the latter stage controlled by diffusion. The activation energies of the gas-based reduction for different gas atmosphere and different stage are studied. In addition, this study firstly presents that the diffusion-control step is significantly shortened with the increase of the ratio of H 2 /(CO + H 2 ). SEM results indicate that pellet which was reduced in H 2 atmosphere has a lot of inner pores (0–5 μm) in mineral grains. Inner pores provide gas channels and decrease gas diffusion resistance during the reduction process so that the diffusion-control step is shortened. These results can serve as a reference to the utilization of hydrogen and carbon monoxide on VTM ore. [ABSTRACT FROM AUTHOR]

Herein, we reduced PdCl 4 2− ions on the synthetized cuprous phosphide/reduced graphene oxidation (Cu 3 P/RGO) hybrids to improve the catalytic activity and durability of Pd nanocrystals. In comparison with commercial Pd/C and Pd/RGO catalysts, the Pd/Cu 3 P/RGO exhibit high electroactivity and durability toward alcohol oxidation in alkaline medium. The enhanced catalytic performance of Pd/Cu 3 P/RGO is due to the high electrochemically active surface area, which can be ascribed to the interactions between Cu 3 P/RGO and Pd nanocrystals. The investigation of Cu 3 P/RGO as a promoter in alcohol electrooxidation will offer an opportunity in the field of direct alcohol fuel cells (DAFCs). [ABSTRACT FROM AUTHOR]

A novel and magnetically separable N doped-cobalt carbon composite (Co-NC) was facilely synthesized via thermal treatment of Co 3 O 4 -melamine mixture in atmospheric condition. The physicochemical properties of the composite were characterized with X-ray diffractometer, Raman spectroscopy, SQUID magnetometer, scanning electron microscope, and X-ray photoelectron spectroscopy. The catalytic ability of the composite was evaluated in reduction of p -nitrophenol and pendimethalin using NaBH 4 as a reductant. The composite showed a good catalytic performance to completely reduce 20 mg L −1 of p -nitrophenol within 7.5 min, and 44 mg L −1 of pendimethaline within 20 min at a dose of 0.27 mg mL −1 and 0.32 mg mL -1 , respectively. The composite also displayed a robust reusability with a small loss of catalytic activity in completion of four repetitive p -nitrophenol reduction cycles, demonstrating its potential utility as an alternative to noble-metal catalysts. [ABSTRACT FROM AUTHOR]

Studies were carried out to prepare W-5Cr-5Si alloys (wt.%) by silicothermic co-reduction route using mixed oxides of tungsten tri-oxide and chromium oxides as reactants and Si as the reducing agent as well as alloying element. Optimum charge composition was found out by carrying out multiple co-reduction experiments for the formation of targeted alloys. The consolidated alloy was produced in a single step using the exothermic nature of the reduction reactions. The as-cast alloys were characterized with respect to chemical composition, phases, microstructure, hardness and oxidation properties. The multiphase alloy was composed of (W, Cr) 5 Si 3 matrix and discontinuous (W, Cr) ss phases with a relative volume of about 40%. [ABSTRACT FROM AUTHOR]