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Solution-processed and annealing-free zirconium acetylacetonate electron-selective contacts for efficient crystalline silicon solar cells
No full textThe interfaces between n-type silicon (n-Si) and metal electrode contact have enormous influences on the performance and stability of silicon solar cells. Recently, it has been proven that the carrier-selective contact (CSC) is an effective strategy to improve the device efficiency. Herein, a solution-processed and annealing-free zirconium acetylacetonate (ZrAcac) layer is used as an electron-selective contact for fabricating efficient crystalline silicon solar cell. This contact scheme enabled a reduction in both the contact resistivity and the work function at the interface between n-Si and Al, which can be attributed to the dipole formation at the contact interface induced by charge transfer. The application of this ZrAcac based contact was shown to consistently improve all device parameters reaching a maximum power conversion efficiency of 17.8% with a high fill factor of 81.1%, and greatly improve the device stability. This work demonstrated that the ZrAcac layer can provide sufficient energy alignment and enhanced carrier selectivity for efficient and stable photovoltaic devices
Tribological and anti-corrosion performance of epoxy resin composite coatings reinforced with differently sized cubic boron nitride (CBN) particles
No full textA series of high solid content (30 wt%) epoxy resin (EP) composite coatings reinforced with differently sized cubic boron nitride (CBN) particles were fabricated successfully on 304L stainless steel. Polydopamine (PDA) was used to improve the dispersibility of CBN particles in EP. The structural and morphological features of the CBN particles and the composite coatings were characterized by Raman spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Moreover, a UMT-3 tribometer and surface profiler were used to investigate the tribological behaviors of the as-prepared composite coatings. Electrochemical impedance spectroscopy (EIS) and Tafel analysis were used to investigate the coatings' anti-corrosion performance. The results demonstrated that the CBN fillers could effectively enhance the tribological and anti-corrosion properties of the EP composite coatings. In addition, when the additive proportion of the microsized (5 mu m) and nanosized (550 nm) CBN particles was 1:1, the tribological property of the EP composite coatings was optimal for dry sliding, which was attributed to the load carrying capability of the microsized CBN particles and the toughening effect of the nanosized CBN particles. However, when the additive proportion of the microsized and nanosized CBN particles was 2:1, the tribology and corrosion resistance performance were optimal in seawater conditions. We ascribed this to the load-carrying capacity of the microparticles, which played a more important role under the seawater lubrication condition, and the more compact structure, which improved the electrolyte barrier ability for the composite coatings
Structural Phase Transformation in Amorphous Molybdenum Disulfide during Friction
No full textMolybdenum disulfide (MoS2) coatings are known for their ultralow friction coefficient (0.005) due to the appearance of tribofilms with a lamellar structure. Nevertheless, the dynamics of MoS2, sheet formation are rarely studied. In this paper, temperature-, load-, and slippage-induced transition of pure MoS2 from an amorphous structure to a higher-order structure were studied by means of reactive molecular dynamics. The forming process of MoS2 flake conforms to the characteristics of classical nucleation theory (CNT). The relevant atomic-scale processes, such as nucleation, growth, approaching, aligning, and shaping, are analyzed and explained. The results confirm that the sliding process involved in friction does promote the formation of MoS2 tribofilms. In addition, the sliding behavior can facilitate the transformation of the crystal structure, which greatly reduces grain boundary defects in molybdenum disulfide flakes. Our findings may have important implications to gain insight into the crucial factors that contribute to rapid and effective structural transformation in friction processes
Mutual Performance Enhancement within Dual N-doped TiO2/Si/C Nanohybrid Lithium-Ion Battery Anode
No full textDual N-doped TiO2/Si/C ternary nanohybrid has been successfully prepared via a facile solvothermal method. Polyethylene glycol (PEG) is applied to disperse TiO2 and silicon precursors. After polymerization with hexamethylene diisocyanate (HDI) and calcination, N-doped TiO2 and carbon matrix are obtained. The contents of Si, TiO2 and C in N-doped TiO2/Si/C are about 10 %, 72 % and 18 % respectively. N-doped TiO2/Si/C shows an excellent electrochemical performance due to combined advantages of Si, TiO2 and C. The initial discharge/charge specific capacity of the N-doped TiO2/Si/C is 658/548 mAh g(-1) at a current of 0.1 A g(-1) with a coulombic efficiency of 83 %. A reversible capacity of 538 mAh g(-1) is achieved after 80 cycles. While at the high current of 5 A g(1), the specific capacity of the N-doped TiO2/Si/C can still reach 120 mAh g(-1). Electrochemical impedance spectroscopy measurements prove the improved electric conductivity after N-doping
Photocatalytic oxidation of benzyl alcohol and the photoelectrochemical water splitting of visible light-activated TiO2 nanostructures prepared by one-step titanium anodization
No full textDoped TiO2 nanostructures have been prepared by one-step anodization of titanium in an ethylene glycol-based electrolyte with different concentrations of potassium hexacyanocobaltate and their catalytic activity in photocatalytic oxidation of benzyl alcohol to benzaldehyde, and photoelectrochemical water splitting under visible light has been investigated in this work. Field emission scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy and UV-visible techniques have been used to determine the effect of the concentration of the doping agent on the morphology, structure and optical properties of doped TiO2 thin films. Doped TiO2 nanostructures show significant morphological differences in comparison with commercial bare TiO2 nanotube samples, based on SEM analysis. Different electrochemical methods have been used to study the effect of the concentration of the doping agents on the photoelectrocatalytic activity of the samples. The as-anodized doped TiO2 electrodes were observed to show higher photocatalytic activity compared with the bare TiO2 due to the high absorption of visible light and reduction in the recombination of photogenerated charges. Very high surface area, good photocatalytic performance, moderate conversion (about 42%) and high selectivity (>99%) for oxidation of benzyl alcohol to benzaldehyde at ambient temperature under visible light illumination in acetonitrile solvent were shown by the doped TiO2 nanoporous sample anodized in electrolyte containing 0.015 M potassium hexacyanocobaltate (sample CT15). Finally, the photoelectrochemical water splitting efficiency of the samples prepared has also been investigated
Low-Temperature Synthesis of Micro-Mesoporous TiO2-SiO2 Composite Film Containing Fe-N Co-Doped Anatase Nanocrystals for Photocatalytic NO Removal
No full textA simple low-temperature (< 100 degrees C) hot-water treatment was used to synthesize Fe-N co-doped anatase nanocrystals which were uniformly dispersed in micro-mesoporous SiO2 host film for the first time. The Fe-N co-doped TiO2-SiO2 (FNTS) film exhibited stable photocatalytic activities. A NO removal efficiency of 56.1% was achieved under simulated solar light irradiation without any obvious inactivation in 30 min. The transient photocurrent response of FNTS film is approximately six times higher than that of non-doped TiO2-SiO2 film, indicating the superior charge separation of photo-generated electron-hole pairs. Electron spin resonance analysis showed that the center dot OH and center dot O-2(-) radicals were key species to remove NO. Combined with quantitative reaction intermediates, the possible photocatalytic degradation mechanism of NO over FNTS film was proposed. In addition, the FNTS thin films exhibited intrinsic super-hydrophilicity and durable self-cleaning property even after 6 months of storage in the dark. This work provides a facile method to load the catalyst on thermal labile substrates, such as soda-lime glass and organic polymer for more practical applications. Graphic Abstract A simple low-temperature (< 100 degrees C) hot-water treatment was used to synthesize micro-mesoporous TiO2-SiO2 composite film, which shows good self-cleaning ability and superior photodegradation activity for NO removal under solar light. [GRAPHICS]
A Feasible Method for Evaluating Energy Consumption of Industrial Robots
No full textEstablishing energy consumption models is important to achieve green manufacturing for robot automatic lines. To deal with the practical issue that the joint torque are difficult to be acquired in industrial robots, this paper aims to build dynamics model of robots from the motor torque to the robot motion. The Newton-Euler method is used to construct the model in linearin-parameter form. In addition, as the conventional excitation signals, such as sine sweep and pseudo random binary signal, are not applicable for robots with closed control architectures, this paper proposes a method to use robot built-in point-to-point motion trajectory for the system identification. In this way, the parameters in the dynamics model are identified by linear least square. Eventually, energy consumption model can be formed. Simulation and experiments are conducted on a KUKA KR60-3 robot to verify the effectiveness of the proposed method. By experiment, the accuracy of prediction of energy consumption is as high as 90.54%
The Abuse Characteristics of Amphetamine-Type Stimulants in Patients Receiving Methadone Maintenance Treatment and Buprenorphine Maintenance Treatment
No full textObjective: The purpose of this study was to retrospectively investigate the abuse characteristics of amphetamine-type stimulants (ATS) in patients receiving methadone maintenance treatment (MMT) and buprenorphine maintenance treatment (BMT). Methods: A total of 58 MMT and 51 BMT patients abusing ATS were recruited from the drug maintenance treatment clinic of Ningbo Addiction Research and Treatment Center from January 2018 to December 2019. They were assessed using the amphetamine abuse questionnaire (AAQ), addiction severity index (ASI) and Barratt impulsiveness scale (BIS). Moreover, 40 MMT control patients, 40 BMT control patients and 20 healthy controls were also assessed using the BIS. All information was collected using the amphetamine abuse questionnaire (AAQ), Chinese version of addiction severity index (ASI-C) and Chinese version of Barratt impulsiveness scale (BIS-C) conducted by qualified psychologists. Results: The interval of amphetamine use in the MMT group was shorter than the BMT group (P < 0.05). The drug use subscale score of ASI was higher in the MMT group than the BMT group (P < 0.05). The respective and total scores of attentional impulsiveness, motor impulsiveness and non-planning impulsiveness in BIS in the MMT group were all higher than the MMT control group (P < 0.05). The scores of motor impulsiveness and nonplanning impulsiveness in the BMT group were higher than the BMT control group (P < 0.05). The respective and total scores in BIS in the MMT control group and the BMT control group were all higher than those in the healthy controls. Conclusion: The patients showing amphetamine abuse in maintenance therapy had a greater impulsiveness than those having other simple maintenance treatments, and patients under MMT may be more addicted to amphetamines in comparison with those having BMT
Surface treatment of titanium by in-situ anodizination and NiO photodeposition: enhancement of photoelectrochemical properties for water splitting and photocathodic protection of stainless steel
No full textChromium-doped TiO2 nanotubes (CT) film on titanium substrates was prepared by an in-situ electrochemical anodizing method and then a wide range time was used for photodeposition of NiO on the surface of CT to optimize the condition for the fabrication of NiO-chromium-doped TiO2 nanotubes (NCT). Various techniques were used to characterization which confirms the anatase form of TiO2 as well as the presence of NiO. The UV-Vis spectra exhibit that deposited of NiO on the surface of CT progressively enhances visible light absorption. Photoelectrochemical performance of as-prepared samples was studied in the presence and absence of light which showed that NCT samples are markedly beneficial for reducing photo generated charges recombination. NCT2 sample effectively increased photocurrent density four times more than the bare CT sample and showed the maximum amount of H-2 evolution during water splitting after 60 min. In addition, Tafel tests are performed to investigate the photocathodic protection of as-prepared samples for 403 stainless steel. It was observed that the photocathodic protection performance is achieved for NCT2 which prepared at a photodeposition time of 20 min
Flexible conductive hydrogel fabricated with polyvinyl alcohol, carboxymethyl chitosan, cellulose nanofibrils, and lignin-based carbon applied as strain and pressure sensor
No full textEmploying renewable, environmentally friendly, low-cost lignocellulose to design flexible pressure sensitive hydrogel (PSH) as strain and pressure sensors in wearable electronics represents the global perspective to build sustainable and green society. Lignin-based carbon (LC), as the conductive filler, were uniform distributed in the hydrogel system composing by polyvinyl alcohol (PVA), carboxymethyl chitosan (CMC), and cellulose nanofibrils (CNF) to assemble PSH. The analysis revealed that the cross-linking of components through hydrogen bonds formed among hydroxyl group, amino group and carboxyl group exerts the hydrogel with stretching ability and fatigue resistance. The results indicated that the fracture tensile strength and compression stress of the PC/CNF/LC hydrogel were 133 kPa and 37.7 kPa, respectively. Because of the existence of LC, PSH hydrogel exhibits the sensitive deformation-dependent conductivity and can be applied as a flexible strain and pressure sensor monitoring body motions such as elbow flexion, finger bend and palm grip. Therefore, the assembled PSH hydrogel is a prominent candidate applying as the strain and pressure sensor devices. (C) 2020 Elsevier B.V. All rights reserved