Search

Glass-ceramic sulfide solid electrolytes like Li7P3S11 are practicable propellants for safe and high-performance all-solid-state lithium-sulfur batteries (ASSLSBs); however, the stability and conductivity issues remain unsatisfactory. Herein, we propose a congener substitution strategy to optimize Li7P3S11 as Li7P2.9Sb0.1S10.75O0.25 via chemical bond and structure regulation. Specifically, Li7P2.9Sb0.1S10.75O0.25 is obtained by a Sb2O5 dopant to achieve partial Sb/P and O/S substitution. Benefiting from the strengthened oxysulfide structural unit of POS33- and P2OS64- with bridging oxygen atoms and a distorted lattice configuration of the Sb-S tetrahedron, the Li7P2.9Sb0.1S10.75O0.25 electrolyte exhibits prominent chemical stability and high ionic conductivity. Besides the improved air stability, the ionic conductivity of Li7P2.9Sb0.1S10.75O0.25 could reach 1.61 × 10-3 S cm-1 at room temperature with a wide electrochemical window of up to 5 V (vs Li/Li+), as well as good stability against Li and Li-In alloy anodes. Consequently, the ASSLSB with the Li7P2.9Sb0.1S10.75O0.25 electrolyte shows high discharge capacities of 1374.4 mAh g-1 (0.05C, 50th cycle) at room temperature and 1365.4 mAh g-1 (0.1C, 100th cycle) at 60 °C. The battery also presents remarkable rate performance (1158.3 mAh g-1 at 1C) and high Coulombic efficiency (>99.8%). This work provides a feasible technical route for fabricating ASSLSBs.

Carbon fiber-reinforced lightweight substrate with electric conduction and heating was proposed to protect slope plants in winter. Through unconfined compressive strength-resistivity tests, the stress–strain-resistivity curves of carbon fiber-reinforced lightweight substrates with different moisture content under wetting–drying cycles were drawn, and the variation of stress–strain-resistivity of carbon fiber-reinforced lightweight substrate under compression was systematically analyzed. The results show that the strength and resistivity of the substrate decreased with the increase of water content. In the unconfined compressive strength-resistivity test, the decrease of the resistivity of the sample is mainly due to the compaction of soil particles and the soil saturation caused by the discharge of pore gas. However, it will increase due to the increase of cracks when the sample is at failure, but the global resistivity still decreases. The substrate subjected to wetting–drying (W-D) cycles could crack after the first W-D cycle due to erosion of the internal structure, which resulted in a significant decrease in the strength of the substrate and an increase in the resistivity. However, with the increase of W-D cycles, the variation of unconfined compressive strength tended to be constant, but the resistivity continued to increase.

Dynamic color-tunable fluorescent materials are sought-after materials in many applications. Here, we report a polymeric matrix-regulated fluorescence strategy via synergistically modulating aggregation-induced emission (AIE) properties and the Forster resonance energy transfer (FRET) process, which leads to tunable dynamic variation of color and photoluminescence (PL) intensity of fluorescent polymeric nanoparticles (FRET-PNPs) driven by photoirradiation. The FRET-PNPs were prepared via a facile one-pot miniemulsion copolymerization with the tetraphenyletheyl (TPE) and spiropyran (SP) units chemically bonded to the polymer matrix. The FRET-PNPs exhibited dynamic variation of fluorescence properties (colors and PL intensity) under photoirradiation on the timescale of minutes. The variation of the polymer matrix composition could deliberately influence the AIE property of TPE units and the isomerization process of SP to merocyanine units, which further affect the FRET efficiency of FRET-PNPs and, eventually, lead to versatile dynamic fluorescence variation. The dynamic fluorescence property as well as the excellent processability and film formation ability of FRET-PNPs allowed for diverse applications, such as warning labels, dynamic decorative painting, and multiple information encryption. Without sophisticated molecular design or tedious preparation processes, a new perspective for the design, fabrication, and performance optimization of fluorescent nanomaterials for innovative applications was proposed.

The containment spray system is a vital part of the nuclear power plant to reduce the temperature and pressure within the containment during a hypothetical severe accident, which is bound up with the safety of the nuclear reactor. To investigate the performance of the containment spray system, the model coupling the multi-droplets motion and phase change model inducing the local gas parameters surrounding the droplets is formulated. The proposed model is utilized to simulate the droplet spraying process in the containment. The time evolution of various parameters of the containment spray system including the temperature, pressure, steam mass fraction, droplet sizes and trajectories were presented against the experimental results. Furthermore, the influence of the spray droplet parameters on the system performance was analyzed. The results indicate that the system performance is strongly dependent on the radii of the spray droplets, spray mass flow rate and the position distribution of the spraying nozzles, in the range of the temperature, pressure, droplet sizes, velocities and spray mass flow rate investigated. This study presents a droplet motion and phase change model that can be applied to droplet spray characteristics simulation, and performs a systematic analysis of the containment spray system performances. The results can be used to support the design and optimization of spray cooling systems in the containment and other applications.

Low-cost spray deposition is employed to investigate the possibility of using earth-abundant ZrO2 as the antireflection coating in Si solar cells. Structural, optical, and electrical properties of spray-deposited ZrO2 films are investigated. Spray-deposited ZrO2 is highly transparent with a refractive index of 2.0 at 600 nm. Reflection and transmission spectra of ZrO2 films reveal that the optical properties of spray-deposited ZrO2 are comparable to SiNx deposited by plasma-enhanced chemical vapor deposition. Atomic force microscopy studies show that spray-deposited ZrO2 is crack/pore-free and its surface roughness has a root-mean-square value of 0.7 nm for a 75-nm film. Spray-deposited ZrO2 at 550 °C is polycrystalline with a cubic lattice but largely amorphous at 450 °C as determined by X-ray diffraction. Capacitance-voltage measurements indicate that spray-deposited ZrO2 has a negative charge density of 8.19 × 1011 cm−2 for a 75-nm film. Post-deposition annealing results in a significant decrease in oxide capacitance which is attributed to the formation of SiO2 at the ZrO2/Si interface. The resistivity of as-deposited ZrO2 is 3.69 × 1012 Ω-cm and it improves to 2.46 × 1013 Ω-cm after post-deposition annealing in air at 600 °C for 1 h.

Electrochemical reduction of CO2 to value-added carbon and oxygen in lithium-containing molten carbonates at 723 K is a promising approach to the efficient utilization of CO2. It was recently reported that the cathodic process in this transformation is controlled by the sluggish diffusion of the generated O2− ions. The formation of Li2O on the cathode results in partial cathodic passivation of the cathode. To accelerate the reaction kinetics and also eliminate the concentration polarization of the resulting Li2O, the effect of bubbling CO2 through a hollow electrode was examined in this work using a home-made hollow gas bubbling (HGB) electrode. The localised CO2 bubbling not only accelerates the transport of O2− ions by agitating the electrolyte nearby, but the CO2 also reacts with Li2O to form the more soluble Li2CO3. Cyclic voltammetry (CV), linear sweep voltammetry (LSV) and constant current electrolysis were conducted in the melt at 723 K to study the depolarization mechanisms involved in the CO2 bubbling reaction. Using the HGB electrode, the steady-state current density increased from 15.3 mA/cm2 to ~200 mA/cm2 at a potential of −2.4 V (vs. Ag/Ag2SO4). The HGB electrode effectively improved the cathodic kinetics, which is beneficial for CO2 capture and electrochemical conversion. Keywords: CO2 conversion, Molten carbonates, Passivation, Electrode kinetics

Si passivated emitter rear contact (PERC) are expected to become the dominant cell technology in the near future [1]. In PERC cells, a thin layer of Al2O3 is deposited on the rear of the Si cell to reduce rear surface recombination on p-type Si by chemical and field-effect passivation [2]. Optically the Al2O3 film is supported by a thicker SiNx layer stacked on Al2O3, and the low refractive index of SiNx improves light trapping in the Si cell by rear reflection [3]. In commercial production, the Al2O3 film is prepared by atomic layer deposition (ALD). ALD is a slow process and the precursor for Al2O3, Al2(CH3)6, is expansive and pyrophoric. For these reasons the thickness of the Al2O3 film in PERC cells is limited to ~10 nm and the 80-nm SiNx layer is deposited on Al2O3 by plasma-enhanced chemical vapor deposition (PECVD). It is noted that the refractive index of Al2O3 is lower than that of SiNx, 1.6 vs. 2.0 [4,5], so a thicker Al2O3 film on the rear of the PERC cell should provide better rear passivation and optical trapping than an Al2O3/SiNx stack. This requires a low-cost process to deposit thicker Al2O3 on Si. In this talk, we report the suitability of spray-deposited Al2O3 for rear passivation and optical trapping in Si PERC cells. Electrical, optical and structural properties of spray-deposited Al2O3 are investigated and compared to the industrial standard ALD Al2O3/PECVD SiNx stack. It was found that spray-deposited Al2O3 has a negative charge density of 3.19×1012 cm–2 for an 80-nm film, indicating that spray-deposited Al2O3 can serve as the passivation layer. Optical properties of spray-deposited Al2O3 are identical to the ALD Al2O3/PECVD SiNx stack, suggesting that spray-deposited Al2O3 can also serve as the optical trapping layer. It was also found that spray-deposited Al2O3 is crack and pore free, and its surface roughness has a root-mean-square value of 0.42 nm for an 80-nm film. Spray-deposited Al2O3 is amorphous and its composition is slightly Al rich. The resistivity and breakdown field of 80-nm spray-deposited Al2O3 are ~1014 Ω-cm and 3.28 MV/cm, respectively. These properties suggest that spray-deposited Al2O3 is a promising candidate to replace the ALD Al2O3/PECVD SiNx stack in Si PERC cells. [1] C. Roselund, International Technology Roadmap for Photovoltaic (ITRPV), 7, 21, (2016). [2] N. Batra, J. Gope, R. Singh, J. Panigrahi, S. Tyagi, P. Pathi, S. K. Srivastava, C. M. S. Rauthan, P. K. Singh, Phys. Chem. Chem. Phys., 16(39), 21804 (2014). [3] B. Vermang, H. Goverde, L. Tous, A. Lorenz, P. Choulat, J. Horzel, J. John, J. Poortmans, R. Mertens, Prog. Photovolt. Res. Appl., 20(3), 269 (2012). [4] M. D. Groner, F. H. Fabreguette, J. W. Elam, and S. M. George, Chem. Mater., 16(4), 639 (2004). [5] J. Schmidt and M. Kerr, Sol. Energy Mater. Sol. Cells, 65(1-4), 585 (2001).

Spray-deposited hematite Fe2O3 and spin-coated anatase TiO2 thin films were annealed under H2S in order to investigate the effect of sulfurization by H2S. Sulfurized films were characterized using UV–vis spectrophotometry, X-ray diffractometry, Raman spectroscopy, field-emission scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Sulfurized Fe2O3 and TiO2 films are composed of multiple phases. The Fe2O3 film undergoes phase transformation from hematite into a mixture of magnetite (Fe3O4) and pyrrhotite (FeS) at annealing temperatures above 250 °C. At 450 °C α-Fe2O3 is fully transformed into pyrite (FeS2). The TiO2 film transforms into a mixture of TiO2 and TiS2. TiS2 formation begins at temperatures above 550 °C. At 700 °C, TiO2 is completely transformed into TiS2.

Liquid organic electrolytes are mostly used in commercial lithium-ion batteries, due to their advantages of high conductivity and excellent wetting of the electrode interface. However, liquid organic electrolytes are flammable and volatile, causing safety issues of commercial lithium-ion batteries in electric vehicles. Recently, all-solid-state lithium secondary batteries have attracted great attention owing to their high safety and increased energy density, and are considered the most promising next generation energy storage systems. The most essential components are solid electrolytes for all-solid-state lithium batteries. Among various inorganic solid electrolytes, sulfide solid electrolytes have received widespread attention because of their high ionic conductivity and good mechanical properties. Herein, we summarize the development of several typical sulfide solid electrolytes and the problems to be addressed in emerging all-solid-state lithium batteries. Finally, the future development directions of sulfide electrolytes and all-solid-state lithium batteries are briefly discussed.

In this work, the acoustic performance of an anechoic layer, which contains horizontally-distributed cylindrical holes, has been studied using identified viscoelastic dynamic parameters. First, the reflection coefficients of two different viscoelastic anechoic layers (one solid and the other perforated), tested in a water-filled pipe, have been used to develop the identification method for viscoelastic dynamic parameters. In the proposed method, the complex longitudinal wavenumber and the complex transverse wavenumber can be obtained by solving the characteristic equation of viscoelastic cylindrical tube. Then, simulations have been performed using COMSOL software to predict the acoustic performance of the anechoic layer. Based on the model and the identified viscoelastic parameters, the effects of different structural properties, including the radius of hole, the hole horizontal spacing, and the arrangements of holes, on the sound absorption of anechoic layer have been analyzed and discussed. Particularly, the acoustic performance of an anechoic layer under oblique incidence has also been considered.

Surface states are a classic obstacle in semiconductor technologies dating back to the John Bardeen era. We propose a generic approach, i.e., valence-mending passivation, to remove surface states. This paper reviews valence-mending passivation of the Si(1 0 0) surface, which is accomplished by depositing a monolayer of chalcogen atoms on Si(1 0 0). Methods for preparing an atomically-clean surface and depositing a self-limited monolayer of chalcogen atoms on Si(1 0 0) are developed in molecular beam epitaxy, solution passivation, and chemical vapor deposition. The passivated surface exhibits unprecedented electrical and chemical properties that are atypical of three-dimensional bulk semiconductors. The Schottky barrier heights for various metals now obey the Mott-Schottky theory on valence-mended Si(1 0 0). Metals of very-low and very-high workfunctions produce record-high and record-low Schottky barriers on the passivated surface. The record-high barrier demonstrated is 1.14 eV for an Al/sulfur-passivated p-type Si(1 0 0) junction, which exceeds the bandgap of Si. The record-low barrier is lower than 0.08 eV for an Al/sulfur-passivated n-type Si(1 0 0) junction and that barrier is likely negative at –0.02 eV. These record Schottky barriers show good thermal stability up to 500 °C upon annealing. Potential applications of valence-mending passivation include: (1) new approaches to Ohmic contacts for both heavily- and lightly-doped semiconductors, (2) a new diode that is an intermediate between a Schottky junction and a p-n junction, (3) suppressed surface and grain boundary recombination in optoelectronics and photovoltaics, and (4) the ideal substrate for van der Waals epitaxy of two-dimensional materials. The limitations of the current methods in characterizing extremely-low and negative Schottky barriers are outlined.

Moisture diffusion in cement-based materials significantly impacts its durability. In this study, we analyzed the effect of adding a waterproofing agent and nano-SiO2 (NS) on the water transportation process in mortar using capillary water absorption tests and nuclear magnetic resonance (NMR) technology. The results indicate that the combined action of the waterproofing agent and nano-SiO2 drastically reduce the capillary water absorption coefficient and have a more significant impact than only adding the waterproofing agent. The moisture diffusion in different sections of the mortar during the water absorption process is obtained from the NMR test results and two function models. Comparative studies indicate that the NMR test results have good correlation with the capillary water absorption test results and provide accurate process data. The NMR analysis results offer a new analytical method to characterize the porosity of cement-based materials by continuously monitoring small-pitch sections.

Lanthanide-based upconversion nanoparticles can convert low-energy excitation to high-energy emission. The self-assembled upconversion nanoparticles with unique structures have considerable promise in sensors and optical devices due to intriguing properties. However, the assembly of isotropic nanocrystals into anisotropic structures is a fundamental challenge caused by the difficulty in controlling interparticle interactions. Herein, we report a novel approach for the preparation of the chain-like assemblies of upconversion nanoparticles at different scales from nano-scale to micro-scale. The dimension of chain-like assembly can be fine-tuned using various incubation times. Our study observed Y-junction aggregate morphology due to the flexible nature of amphiphilic block copolymer. Furthermore, the prepared nanoparticle assemblies of upconversion nanoparticles with lengths up to several micrometers can serve as novel luminescent nanostructure and offer great opportunities in the fields of optical applications.

This paper focuses on optimization of the light-induced Al plating process to promote a dense adherent film to the Si solar cell as the front electrode. Electrochemical capacitance-voltage and sheet resistance measurements were used to optimize the laser patterning process for the SiN x layer. A recipe to remove contaminants and laser damage on the Si surface after SiN x patterning was developed. Atomic force microscopy revealed the minimum etch time to remove all the original Si surface which was damaged and contaminated. Various plating conditions including temperature, plating voltage, and light intensity were investigated. The lowest Al resistivity obtained is $4\times 10^{-6}\ \mathrm{\Omega}-\mathrm{cm}$ , which is comparable to that of electroplated Cu.

In order to optimize the design of bypass valve structure and optimize the parameters of motor and power supply, the torque characteristics of bypass valve were studied by theoretical analysis and numerical simulation. The results show that: after the inner rotary valve of the bypass valve is opened, the fluid will produce hydraulic torque, and the hydraulic torque is inversely proportional to the opening of the rotary valve, and proportional to the fluid velocity and pressure. The opening degree of rotary valve is in the range of 0°~10°, and the reduction of hydraulic torque per unit opening degree is much larger than that of 10°~30°. With the increase of velocity and pressure, the reduction of hydraulic torque per unit opening increases gradually. The research in this paper has an important guiding role in the design and optimization of the adjustable speed internal detector.

Micro thermophotovoltaic system, a chemical energy to electrical output device, has been challenged for application because of burning instability, high heat loss ratio and low energy conversion efficiency. A combustor coupling with pins and exit-step configurations is developed to improve system performance. Effects of pins arrangement and exit-step length on the combustion characteristics and thermal performance are investigated with the eddy-dissipation concept (EDC) model and detailed H2/air combustion mechanism. The results indicate that the premixed flame anchors at combustor upstream near the smaller pins where favorable ignition conditions are established. Besides, the appropriate exit-step length improves the heat transfer of gas-solid and energy efficiency, where the length ratio of exit-step to combustor δ = 0.66 is the best for reducing exhaust loss. Furthermore, the combustor coupling with pins and exit-step achieves a stable flame, high energy efficiency and thermal performance. For the micro thermophotovoltaic system with the combustor and InGaAsSb PV cells, radiation efficiency 35.6 % and electric output 2.26 W can be obtained, that is, the system efficiency is 18.7 % higher than that of the straight-channel combustor at hydrogen flow rate 3.75 g/h and equivalence ratio Φ = 1.0.

Electrochemical reduction of CO2 to value-added carbon and oxygen in molten carbonates is a promising approach to the efficient and economical utilization of CO2. Fully understanding the electrode kinetics is crucial to scaling up the process. Herein, the reduction kinetics were studied by cyclic voltammetry, linear sweep voltammetry and potentiostatic electrolysis. The electrolytic products prepared at selected potentials were characterized by X-ray diffraction. It was found that the cathode surface was partially covered by insoluble lithium oxide and that the sluggish diffusion of the O2– ion was the rate-determining step during carbon deposition at 723 K. When the temperature is increased to 923 K, the reaction kinetics are accelerated around 100-fold with a limiting current density of 1.5 A/cm2. Knowledge of this mechanism should prove useful in the design of a pilot cell based on molten salt CO2 capture and electrochemical transformation (MSCC-ET) technology. Keywords: Carbon dioxide utilization, Molten carbonates, Electrochemical reduction, Electrode kinetics, Rate-determining step

As a distinctive supportable route, the solvent-free synthesis of zeolites not only minimizes the problems of conversional hydrothermal synthesis, but also greatly increases the product yields with advantageous characteristics, such as reduced waste production and a hierarchical pore structure. Herein, we demonstrate using in situ crystal Co/SiO2 to form a hierarchical catalyst with Co particles entrapped inside the ZSM-5 body via a solvent-free process. Na-type zeolite catalysts enhanced the production of gasoline-range (C5–C11) products, with Co@NaZSM-5 giving a high selectivity of 68% in the Fischer–Tropsch synthesis. Obviously, all characterizations showed that these solvent-free synthesized samples had high crystallization and a high surface area for mass transfer. This hierarchical zeolite has the potential to be applied to other similar materials owing to its convenient synthesis method, features, and outstanding results.

Molten-salt electrorefining is a promising technique for energy-efficient production of ultrapure solar-grade Si. This work focuses on electropurification to remove impurities from an eutectic CaCl2-CaF2 molten salt for solar-grade Si. Both an as-received salt and a salt used for Si electrorefining have been electropurified by a field-enhanced process and the impurity concentrations before and after purification have been characterized by inductively-coupled plasma mass spectrometry and cyclic voltammetry. More importantly, a new multi-potential electropurification process, enabled by the three-electrode electrolyzer, has been proposed and proven to be more effective in removing all the impurities in the molten salt than a single-potential process. The salt after Si electrorefining has been regenerated to its original purity level before Si electrorefining by the multi-potential process, demonstrating the feasibility of a reusable salt by electropurification.

A novel method to identify the viscoelastic parameters of underwater anechoic coating has been proposed in this present study. Based on two sets of measured reflection coefficients, the viscoelastic parameters can be identified by using the combination of finite element method and Newton's iterative method. The identification method is used to obtain the viscoelastic parameters of polyurethane, and the effects of some experimental errors, including the mismatched amplitude responses and the mismatched phase responses of two hydrophones on the identified results are discussed. Then, an equivalent method is developed to predict the acoustic scattering performance of coated shell. The equivalence kernel is that the equivalent coating has the same reflection coefficient as the original perforated anechoic coating by using the genetic algorithm. In order to verify the accuracy of equivalent method, a direct finite element model (perforated coating – spherical shell) for acoustic scattering simulation is precisely modelled, where the material of coating is selected to be the identified polyurethane. Obtained results are compared to the acoustic scattering of equivalent method (homogenous coating – spherical shell). Good agreement between two models shows that the equivalent method is feasible and effective to predict the acoustic scattering of coated shell. Moreover, it is found that applying the equivalent method greatly reduces the computational expenses compared to the conventional direct model.

Aggregation-induced emission (AIE) polymeric nanoparticles (PNPs) are promising candidates for detection of nitroaromatic explosives. However, the major limitation of these AIE PNPs is the complicated synthesis and deteriorated detection accuracy because of the poor colloidal and morphological stability. This study provided a facile method to construct AIE PNPs with highly cross-linked polymer matrix for sensitive and accurate detection of nitroaromatic explosives. The highly cross-linked AIE PNPs with a ~50 nm particle size were prepared through copolymerization of divinylbenzene (DVB) and a tetraphenylethene (TPE)-based AIE luminogen, (4′-tetraphenyletheyl)pheny-3-butenylether (TPE-PBE), in a water-borne miniemulsion system. Due to the good aqueous dispersibility and highly cross-linked polymer matrix, the poly(DVB-co-TPE-PBE) NPs showed excellent solvent resistance, and sensitive and accurate detection of nitroaromatic explosives in aqueous systems, especially picric acid (PA). Moreover, a rigid poly(DVB-co-TPE-PBE) film could preserve spherical morphology after coating poly(DVB-co-TPE-PBE) NPs onto various substrates (such as filter paper and glass slide). The high surface area and loose packing of poly(DVB-co-TPE-PBE) NPs offered convenience for 2,4-dinitrotoluene to diffuse and interact with TPE-PBE units. Therefore, cost-efficient and portable poly(DVB-co-TPE-PBE)-coated test strips and film on glass slides exhibited fast response, strong quenching ability, and reusability in visual detection of liquid and volatile explosives, respectively.

A series of Zr4+ and/or Al3+ doped LiNi0.83Co0.11Mn0.06O2 are synthesized via a solid phase method. TEM shows that the co-doped specimen consists of a layered core and a coherent interface cation-mixed shell. XRD and XPS results clarify that Zr4+ doping increases the Li+/Ni2+ cation site exchange degree and the concentration of Ni2+. The morphology and structural integrity of the co-doped electrode maintains well, and it provides a higher cycle retention (89.7%) than blank (60.1%) after 150 cycles and a superior capacity of 152.8 mAh g−1 at 7C (only 57.7 mAh g−1 for blank) and an enhanced elevated temperature cycle retention (83.0%) than blank (33.7%) after 100 cycles at 55 °C. Generally, Zr4+ raises the concentration of Ni2+ to keep electric neutrality and then reconstruct a stable interfacial structure to inhibit side reactions, the structural stability could be also enhanced by the strong Zr–O and Al–O bonds. Meanwhile, Al3+ served as centers of positive charge can suppress the phase transformation. Benefiting from the synergistic effect of Zr4+/Al3+, as well as the induced coherent interface cation-mixed shell, co-doped specimen shows enhanced structural stability and the superior electrochemical performance. This study provides a route to prepare advanced layered cathodes for lithium-ion batteries.

Anionic ion species occur in gangue minerals and impact the bioleaching efficiency even at low concentrations. Recently, the detrimental influence of fluoride ions on bioleaching microorganisms has caused great attention in research. However, the tolerance mechanisms of bioleaching microorganisms for fluoride are still unclear. In order to reveal fluoride tolerance, culture experiments with different concentrations of fluoride and ferrous iron-grown Acidithiobacillus ferrooxidans were carried out. The results showed that oxidation-reduction potential, oxidation capacity of iron and cell density were all negatively correlated to the fluoride concentration. The growth of A. ferrooxidans showed a longer delayed time and a slower growth rate when fluoride concentration increased. The fluoride tolerance for A. ferrooxidans could be attributed to the generated ferric ions from ferrous oxidation. Ferric ions reacted with HF to decrease the concentration of F- and finally reduced the toxicity of fluoride on A. ferrooxidans.

The redox flow battery (RFB) is considered one of the most attractive energy storage technologies because of its high efficiency, long service life and great safety. In this work, nitrogen-doped porous graphene (NPG) was achieved by embedding nitrogen atoms into the graphitic matrix via a sacrificial-template-assisted pyrolysis approach, and then was employed to catalyze electrochemically the redox reaction of 1,2-dihydrobenzoquinone-3,5-disulphonic acid (BQDSH2) for aqueous organic RFB application. The electrocatalytic performances of this catalyst toward the BQDS/BQDSH2 redox couple were greatly enhanced, including a 6.7 times higher rate constant and much lower peak potential separation value compared to those of a glassy carbon electrode. Furthermore, a 9,10-anthraquinone-2,7-disulfonic acid (AQDS)/BQDS RFB with NPGs as the cathodic BQDS/BQDSH2 catalyst exhibited a maximum power density of ca. 62.4 mW cm−2, about 3.3 times higher than that of the pristine RFB without NPGs, and a minimal discharge capacity fade during the cycling test. The abundant nitrogen defects in NPGs are beneficial to the BQDS/BQDSH2 redox reaction by providing active sites and enhancing the transfer rate of protons and reactants, contributing to the improvement of AQDS/BQDS RFB performance.

Conventional electroplating of aluminum on silicon often requires a seed layer to overcome the high resistivity of the substrate. In this paper, light-induced plating of aluminum directly on a silicon substrate in an ionic liquid is reported. Without any seed layer, the deposited aluminum has good adhesion to the silicon surface. The resistivity of the aluminum deposits is as low as 4 × 10−6 Ω-cm, which is only about 1.5 times that of bulk aluminum. The suitable wavelength for the light source is 600 nm to 1,000 nm. The effect of plating temperature on morphology of the aluminum deposits is analyzed.

Edge preparation can improve tool life, cutting process stability, and quality of the machined surface. The coated tool must be edge-prepared after grinding to ensure enough bonding area to improve tool life. The influence of edge preparation on milling of aluminum alloy 211Z using the coated carbide tool is investigated via DEFORM simulations and corresponding cutting experiments. In this paper, the influence of edge radius, type of coating (TiN, TiCN, TiAlN, TiSiN, TiCrN), cutting speed, feed, axial depth, and radial depth on cutting force, surface roughness, and temperature is revealed. The results provide a basis for determining the effects of edge preparation. Moreover, theoretical values are used to reveal basic laws governing the cutting process, which may have practical significance.

Pickering emulsion systems have created new opportunities for two-phase biocatalysis, however their catalytic performance is often hindered by biphasic mass transfer process relying on the interfacial area. In this study, lipase-immobilized mesoporous silica particles (LMSPs) are employed as both Pickering stabilizers and biocatalysts. A series of alkyl silanes with the different carbon length are used to modify LMSPs to obtain suitable wettability and enlarge the interfacial area of Pickering emulsion. The results show the water/paraffin oil Pickering emulsions stabilized by 8 carbon atoms silane grafted LMSPs (LMSPs_C8) with a three-phase contact angles of 95&deg, get the relatively large interfacial area. Moreover, the conversion of enzymatic reaction catalyzed by LMSPs_C8 Pickering emulsion system is 3.4 times higher than that unmodified LMSPs with the reaction time of 10 min. Additionally, the effective recycling of LMSPs is achieved by simple low-speed centrifugation. As evidenced by a 6-cycles reaction of remaining 75% of relative enzymatic activity, the protection of 350&ndash, 450 nm mesoporous silica particles can alleviate the inactivation of enzyme from the shear stress and make a benefit to form stabile Pickering emulsion. Therefore, the biphasic reactions in the Pickering emulsion system can be effectively enhanced through changing interfacial area only by the means of adjusting the wettability of biocatalysts.

Mn3O4 anchored nitrogen-doped reduced graphene oxide is fabricated via a facile hydrothermal route by using the Mn2+-GO supramolecular system as precursor and the ammonia as precipitant and nitrogen source. A combined characterization method including UV-vis absorption spectrum, fluorescence spectrum, and zeta potential and particle sizing measurement is adopted to study the interactions between Mn2+ and GO nanosheets. More importantly, the electrochemical activation process of the Mn3O4/N-rGO electrode in 1 mol L−1 Na2SO4 is investigated in detail. It is found that the activation process originates from the conversion of structure and morphology from spinel Mn3O4 to nano-structured birnessite MnO2. The activation process mainly occurs in the first 200 cycles, in which the specific capacitance increases by 88.2%. The electrochemical experimental results indicate that the Mn3O4/N-rGO electrode after the activation process exhibits improved capacitive performances with a specific capacitance of 141 F g−1 at 0.2 A g−1 and a superior cycle stability (90.3% capacitance retention after 5000 cycles). This study will give a further insight into the distinctive electrochemical activation process and the supercapacitive properties of Mn3O4-based materials.

Light-induced electroplating of Al as the front electrode on the n-type emitter of Si solar cells is proposed as a substitute for screen-printed Ag. The advantages and disadvantages of Al over Cu as the front electrode are discussed. The power of a green laser used for patterning of the SiNx antireflection coating is optimized. Conditions for removal of laser damage and contamination on the laser-patterned surface are identified. The effect of plating temperature and post-annealing temperature on Al morphology and resistivity are investigated. Several plating additives are explored to improve the morphology and resistivity of the Al film. Nicotinic acid produces the lowest resistivity of 3.1 μΩ-cm. However, the lowest contact resistivity between light-induced Al and Si is 69 mΩ-cm2 due to laser-induced damage to the emitter. The Al film spikes through the thin n-type emitter when annealed at 500 °C causing cell failure. The process reproducibility is also poor due to atmospheric moisture.

By 2050, the scale of installed solar panels must reach about 100 TWp in order to make a tangible impact on our energy mix and carbon emissions. Thin-film amorphous silicon panels are the only technology today capable of 100 TWp installation. Wafer silicon panels could reach 100 TWp if the silver in silicon panels is replaced with copper or aluminum. Cadmium telluride and copper indium gallium selenide would become technologies of insignificance in the big picture. For energy-efficient production of silicon panels, research is needed in energy-efficient purification of silicon, low kerf loss wafering of silicon, and an Earth-abundant top cell on silicon. Alternatively we can pursue a new cell technology which is more energy efficient than silicon and utilizes only Earth-abundant materials. For any cell technology, research is needed to improve the cost, efficiency, and sustainability including storage technologies for daily to multiyear storage and for regional and global trade of solar electricity, recycling technologies to minimize cost and maximize revenue from waste panels, and systems and applications for real-time and in situ consumption of solar electricity.

Electrochemistry and solar photovoltaics are traditionally considered to be in two different domains of science and technology. However, electrochemistry will play an indispensable role in sustaining the production and deployment of solar panels in the coming decades. This paper presents three examples on how electrochemistry will lead to solutions to several roadblocks to sustainable solar photovoltaics. The first example is storage of intermittent solar electricity through a zinc↔zinc oxide loop which requires two technologies: (1) solar electroreduction of zinc oxide and (2) a mechanically-recharged zinc/air battery. Compared to the hydrogen↔water loop, the zinc↔zinc oxide loop is advantageous for long-term (seasonal to multiyear) storage and global trade of solar electricity. The second example is electrorefining to produce solar-grade silicon from metallurgical-grade silicon. Ultrapure materials by electrolysis is an unanswered challenge in electrochemistry. A two-step three-electrode electrorefining process is proposed. Practical challenges in achieving ultrapure silicon by molten-salt electrorefining are outlined. The final example is metal recovery from waste solar panels. Four metals in silicon panels are worth recovery: silver, lead, tin, and copper. They can be leached out in nitric acid and the leachate contains multiple metals. Sequential electrowinning can recover the metals one by one based on their different reduction potentials. The remaining issues in this process are discussed.

The pulsed laser deposited Ni-based superalloy coating was fabricated with successive 12 layers using single tracks. The microstructure of the deposited coating was observed by scanning electron microscopy (SEM). The grain growth and the grain boundary misorientation were investigated by electron backscatter diffraction (EBSD), the precipitation phase was determined by transmission electron microscope (TEM). The results showed that the dendrites were the most common microstructure in the coating, and the dendritic growth orientation was paralleled to the direction of the laser deposition. The dendrite got coarser and its space was increased with increasing laser deposited layers. Most grains grew along the preferential grain orientation 〈001〉 and formed anisotropy with grain boundaries misorientation angle about 2° in the pulsed laser deposited coating. The grain size along the texture orientation was 3–10 times larger than that in the transverse orientation. The cross section microhardness of the coating ranged between 240–280 HV, and decreased along the depositional direction due to the reasons of the variation of eutectic morphology, grain size distribution, grain misorientation and a small amounts of strengthening phase precipitation.

With the consistent improvement of the laser power and energy, further enhancement of the laser resistant ability of the target board is becoming a more and more crucial task in high energy laser diagnostics and irradiation effect studies. Applications of ceramic materials in high energy laser damage were studied. An aluminum panel was coated with ZrO2 ceramic for high power laser proof. Reflectivity and diffuse reflection characteristics of the coating were investigated at different wavelengths. Numerical simulation was conducted to analyze the thermal response of the coating under high power laser radiation. And, related experiments were carried out with high power fiber lasers. Irradiation experiments indicate that the ceramic layer helps to delay the heat conduction and reduce the peak temperature of the target board.

As solar technology becomes more popular, more modules with limited lifetimes will be manufactured. By 2050 there are expected to be 78 million tons of waste modules, which are rarely recycled today. Each module contains approximately 6 grams of silver, which is the most precious metal found in silicon modules. Hydrofluoric acid is proposed as the leaching agent to remove silver and other metals from the surface of the silicon, while electrowinning is used to recover the silver from the leachate and plate it onto a cathode. The electrowinning setup uses a three-electrode configuration with a pseudo reference electrode to control the half-cell potential. A silver pseudo-reference electrode was found to be sufficient for achieving a high mass recovery rate. Variable voltage trials were conducted and 0.7 V with reference to silver achieved a high mass recovery rate of 96.4% with a high purity of silver. Current efficiency is below 7% for all the voltages tested, which suggests parasitic reactions in the reaction vessel such as O2(g) + 4H+ + 4e− ⇌ 2H2O. The trials at 0.7 V vs silver in a nitrogen purge environment eliminated corrosion at the vapor-liquid interface on the cathode but did not improve the current efficiency. It is possible that the nitrogen purge environment still contains residual oxygen.

With the ever-increasing demand for solar modules nowadays, there is a growing interest in developing an alternative, eco-friendly and low-cost manufacturing process for solar-grade silicon. Silicon electrorefining in a molten salt is a promising technique for producing solar-grade silicon directly from metallurgical-grade silicon with low carbon emission and low energy consumption. Due to the stringent requirement in the purity of the silicon for solar applications (at least 99.9999% or 6N), a high-purity molten salt electrolyte is necessary for the solar-grade silicon electrorefining process. In this report, an electrochemical purification process for the eutectic CaCl2-CaF2 (CaCl2:CaF2 = 86.2:13.8 by weight) molten salt at 900℃ has been studied. The impurity level in the salt was in-situ examined by cyclic voltammetry (CV). After the electrochemical purification process, a decrease in peak current of the CV is observed, indicating the removal of the impurities. According to energy-dispersive x-ray spectroscopic results, Fe, Mn, Mg and Al were successfully extracted from the salt. This electrochemical purification process and in-situ salt purity examination technique are useful for purity control of the molten salt in the solar-grade silicon electrorefining process.

Adding redox-active species into the electrolyte can supply extra capacitance to the carbon-based supercapacitors. However, the devices may suffer from serious self-discharge caused by the shuttling and intermixing of charged active species between the electrodes. Confining these active species in a solid-state electrode material is an effective strategy to avoid this. Inspired by this, we fabricate a three-dimensional reduced graphene oxide confined methylene blue composite via a supramolecular strategy, combined with a hydrothermal reduction and a freeze-drying process. Benefited from the porous and conductive structure of the product, the fast-reversible electrochemical reaction of methylene blue, and the spatial confinement effect of the methylene blue confined in reduced graphene oxide, the as-prepared product exhibits a high-rate capability (311 and 262 F g−1 at 1 and 20 A g−1, respectively) and an excellent cycle stability (96% capacitance retention after 10000 cycles) in a three-electrode system. Moreover, a solid-state symmetric supercapacitor device based on the as-prepared product delivers the maximum energy density of 8.2 Wh kg−1 and outstanding cycle stability. This supramolecular-induced confining active species in reduced graphene oxide strategy provides insight into the fabrication of other high-performance graphene-based pseudocapacitors.

In order to study the thermo-hydro-mechanical-chemical (THMC) behaviors of low-rank coal rich clay (LRCRC), a triaxial testing machine with THMC effects of high pressure and high temperature was built. Then, mercury injection tests, fractal dimension analysis and infrared spectroscopy analysis were carried out on LRCRC specimens subjected to a coupled THMC environment. The results showed that: 1) as the temperature increased, the sub-micro pores gradually transformed into other types of pores. Moreover, the formation rate of new pores during pyrolysis was slower than the expansion rate of existing pores; 2) the overall meso-physical parameters and fractal dimension of specimen decreased first and then increased with the increase in temperature; 3) at a given temperature, for sub-micropores (0–10 nm), the reduction rate of microscopic physical parameters and pore size distribution ratio of specimen under superheated steam was less than that under nitrogen atmosphere. For the other pores (>10 nm), the growth rate of microscopic physical parameters and pore size distribution ratio of specimen under superheated steam was greater than that under nitrogen atmosphere. Compared with nitrogen, water vapor was more favorable for pyrolysis of specimen; 4) at a given temperature, the structural parameters (Car/(Car + C O), Car/Hal) of pyrolysis residues of specimen under superheated steam atmosphere were larger than those under nitrogen atmosphere, indicating that the amount of decomposition of aliphatic hydrocarbons and oxygen-containing functional groups was greater than that under nitrogen atmosphere. The research results in this paper can provide useful theoretical guidance and technical support for mining of low-rank clay rich coal.

Owing to the strong solid-state luminescence of aggregation-induced emission luminogen (AIEgen), polymer/AIEgen nanoparticles (NPs) have great potential in application as high-quality luminescent inks. In this work, polymer/AIEgen NPs with a particle size below 70 nm were efficiently prepared through encapsulation of AIEgens with various colors within polymeric matrix via miniemulsion polymerization. The prepared polymer/AIEgen NPs emitted bright and stable blue, green, or orange-red fluorescence. The polymer/AIEgen NP inks suitable for inkjet printing were conveniently made through addition of a non-ionic surfactant to the emulsions with corresponding polymer/AIEgen NPs. The bright, high-resolution, and UV-responsive images were printed on cotton textiles with polymer/AIEgen NP inks. The microscopic observation indicated that the polymer/AIEgen NPs could form homogenous films onto the cotton fibers. More promisingly, the prepared polymer/AIEgen NPs with various colors had good compatibility, and they could be directly mixed to prepare multicolor polymer/AIEgen NP inks for handwriting.

The existence of serious hysteresis effect for regular perovskite solar cells (PSCs) will affect their performances, however, the inverted PSCs can significantly suppress the hysteresis effect. To data, it has been very rarely reported to simulate the inverted planar heterojunction PSCs. In this paper, the effects of hole transport material (HTM), electron transport material (ETM), and ITO work function on performance of inverted MAPbI3 solar cells are carefully investigated in order to design the high-performance inverted PSCs. The inverted MAPbI3 solar cells using Cu2O, CuSCN, or NiOx as HTM, and PC61BM, TiO2, or ZnO as ETM are simulated with the program AMPS-1D. Simulation results reveal that i) the inverted MAPbI3 solar cells choosing NiOx as HTM can effectively improve the photovoltaic performance, and the excellent photovoltaic performance obtained by using TiO2 as ETM is almost the same as by using ZnO as ETM; ii) the ITO work function increasing from 4.6 eV to 5.0 eV can significantly enhance the photovoltaic performances of Cu2O— based and CuSCN— based inverted MAPbI3 solar cells, and the NiOx— based inverted MAPbI3 solar cells have only a minor photovoltaic performance enhancement; iii) based on the reported ITO work function between 4.6 eV and 4.8 eV, the maximum power conversion efficiency (PCE) of 27.075% and 29.588% for CuSCN— based and NiOx— based inverted MAPbI3 solar cells are achieved when the ITO work function reaches 4.8 eV. The numerical simulation gives that the increase of hole mobility in CuSCN and NiOx for ITO/CuSCN/MAPbI3/TiO2/Al and ITO/NiOx/MAPbI3/TiO2/Al can greatly improve the device performance. Experimentally, the maximum hole mobility 0.1 cm2·V–1·s–1 in CuSCN restricts the photovoltaic performance improvement of CuSCN— based inverted MAPbI3 solar cells, which means that there is still room for the improvement of cell performance through increasing the hole mobility in CuSCN. It is found that NiOx with a reasonable energy-band structure and high hole mobility 120 cm2·V–1·s–1 is an ideal HTM in inverted MAPbI3 solar cells. However, the increasing of electron mobility in TiO2 cannot improve the device photovoltaic performance of inverted MAPbI3 solar cells. These simulation results reveal the effects of ETM, HTM, and ITO work function on the photovoltaic performance of inverted MAPbI3 solar cells. Our researches may help to design the high-performance inverted PSCs.

The microstructure and mechanical properties of IN718 alloy fabricated by laser metal deposition were investigated. The continuous dendritic Laves generated by Nb/Mo microsegregation is dissolved by homogenization, the strengthening phase γ" with dimension about 30 nm precipitates during full heat treatment. The ambient temperature tensile strength of laser metal deposited (LMDed) IN718 alloy is enhanced by heat treatment, and the elevated temperature mechanical properties vary with heat treatment temperature and forming direction. Laves dissolution and complete/partial recrystallization depend on heat treatment, stress release and Nb/Mo concentration gradient. The anisotropy of elevated temperature mechanical properties of LMDed IN718 alloy is caused by the combined effect of directional grains size, higher relative content of texture, superior intergranular strength and residual Laves particles. The fracture mechanism of LMDed IN718 alloy varies with heat treatment temperature. The LMDed IN718 alloy with full heat treatment exhibits superior elevated temperature mechanical properties at 650 °C along building direction. The elevated temperature tensile fracture surfaces consist of cleavage plane and/or dimples, the microvoid coalescence (MVC) occurs in the alloy with full heat treatment, the intergranular (IG) fracture and cleavage plane or quasicleavage (QC) exist in the alloys with 980STA and double ageing.

Rubber-sand mixtures (RSMs) have long been recognized as light filling back material and energy absorbing material with wide usage in civil engineering. As addition of rubber particles into sands usually decreases the strength of base sand, it is necessary to reinforce RSMs to satisfy the need of practical engineering. This paper presents studies on the behavior of geogrid reinforced RSMs. Conventional triaxial shear tests were carried out on reinforced/un-reinforced RSMs. Four kinds of geogrid reinforcing patterns, i.e., horizontal reinforcing with one layer, two layers, three layers, and vertical reinforcing were taken into accounted, and three kinds of confining pressures, i.e., 50 kPa, 100 kPa and 200 kPa were applied. Experimental results indicate that: (1) Comparing to un-reinforced RSMs, the stress-strain curves of RSMs reinforced by geogrid are enhanced in turn for vertical reinforcing, horizontal one layer reinforcing, horizontal two layer reinforcing, horizontal three layer reinforcing respectively. (2) The stress-strain relationship of RSMs reinforced by geogrid exhibits strain hardening characteristics instead of strain softening before reinforced. (3) The reinforcement effect coefficient on the failure stress of RSM is higher than that of pure sand, and at the low confining pressure, this phenomenon is more obvious. (4) Geogrid reinforcement can restore the strength of the RSMs with less effect on the modulus. That is, reinforced RSMs can maintain the merits of low modulus and high strength simultaneously. (5) The stress-strain relationship of the reinforced RSM could be well normalized with the failure stress adopted as the normalized factor, based on the established normalization equation, the stress - strain curves could be predicted well.

Surface states have hindered and degraded many semiconductor devices since the Bardeen era. Surface states originate from dangling bonds on the surface. This paper discusses a generic solution to surface states, i.e. valence-mending passivation. For the Si (100) surface, a single atomic layer of valence-mending sulfur, selenium or tellurium can terminate ~99% of the dangling bonds, while group VII fluorine or chlorine can terminate the remaining 1%. Valence-mending passivation of Si (100) has been demonstrated using CVD, MBE and solution passivation. The keys to valence-mending passivation include an atomically-clean Si (100) surface for passivation and precisely one monolayer of valence-mending atoms on the surface. The passivated surface exhibits unprecedented properties. Electronically the Schottky barrier height between various metals and valence-mended Si (100) now follows more closely the Mott-Schottky theory. With metals of extreme workfunctions, new records for low and high Schottky barriers are created on Si (100). The highest barrier so far is 1.14 eV, i.e. a larger-than-bandgap barrier, and the lowest barrier is below 0.08 eV and potentially negative. Chemically silicidation between metal and valence-mended Si (100) is suppressed up to 500 °C, and the thermally-stable record Schottky barriers enable their applications in nanoelectronic, optoelectronic and photovoltaic devices. Another application is transition metal dichalcogenides. Valence-mended Si (100) is an ideal starting surface for growth of dichalcogenides, as it provides only van der Waals bonding to the dichalcogenide.

A new grain boundary passivation method for multicrystalline silicon using hydrogen sulfide has been developed in this work. It has the added benefit of both hydrogen and sulfur for grain boundary passivation. Minority carrier lifetime of the samples is measured to monitor the effect of passivation. It is found that sulfur passivation takes place at higher temperatures, ∼100◦C higher, than hydrogen passivation, and sulfur passivation results in much higher lifetime gains than hydrogen passivation. Post-annealing in ambient further improves the lifetime of the samples, which is attributed to improved surface passivation on the p-type silicon samples by aluminum oxide. The highest lifetime gain achieved after post-annealing is 6750% over the control sample for hydrogen sulfide annealed samples vs. ∼2400% for forming gas annealed samples. Post-annealing also improves the stability of the passivation. © The Author(s) 2015. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives 4.0 License (CC BY-NC-ND, http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial reuse, distribution, and reproduction in any medium, provided the original work is not changed in any way and is properly cited. For permission for commercial reuse, please email: oa@electrochem.org. [DOI: 10.1149/2.0301505jss] All rights reserved.