Conditions In Nitrogen Atmosphere Research Articles

Efficient and Stable Perovskite Solar Cells with a High Open-Circuit Voltage Over 1.2V Achieved by a Dual-Side Passivation Layer.

Suppressing nonradiative recombination at the interface between the organometal halide perovskite (PVK) and the charge-transport layer (CTL) is crucial for improving the efficiency and stability of PVK-based solar cells (PSCs). Here, a new bathocuproine (BCP)-based nonconjugated polyelectrolyte (poly-BCP) is synthesized and this is introduced as a "dual-side passivation layer" between the tin oxide (SnO2 ) CTL and the PVK absorber. Poly-BCP significantly suppresses both bulk and interfacial nonradiative recombination by passivating oxygen-vacancy defects from the SnO2 side and simultaneously scavenges ionic defects from the other (PVK) side. Therefore, PSCs with poly-BCP exhibits a high power conversion efficiency (PCE) of 24.4% and a high open-circuit voltage of 1.21V with a reduced voltage loss (PVK bandgap of 1.56eV). The non-encapsulated PSCs also show excellent long-term stability by retaining 93% of the initial PCE after 700 h under continuous 1-sun irradiation in nitrogen atmosphere conditions.

Ultra-high temperature tolerant flexible transparent electrode with embedded silver nanowires bundle micromesh for electrical heater

To realize high performance flexible transparent electronics with extreme environmental adaptivity, Ag nanowires (Ag NWs) electrodes should simultaneously meet the requirements of high-temperature tolerance, chemical and mechanical robustness. Herein, a scalable Ag NWs bundle micro-meshes embedded in polyimide (Ag BMs/ePI) conducting film via a facile spray coating and transfer method is reported. Due to the synergistic effect of bundle micromesh and embedded architecture, the Ag BMs/ePI electrode exhibits high thermal stability (370 °C and 400 °C under ambient and nitrogen atmosphere conditions, respectively), low sheet resistance variation (<4%), good corrosion and deformation resistance. As an electrical heater, the Ag BMs/ePI can achieve ~204 °C with the fast thermal response time of ~8 s at 8 V, and exhibits good heating stability under bent condition. This work offers a promising platform for the emerging flexible transparent electronics to adapt extreme environments, especially for those devices which require high-temperature processing.

Cohydrothermal carbonization of waste polyvinyl chloride and wood chip for dechlorination

The co-hydrothermal carbonization (Co-HTC) of polyvinyl chloride (PVC) film and wood chip (WC) was conducted at 200-260oC in an autoclave filled in air or nitrogen for the chemical recycling of wastes with dechlorination of PVC. Effects of the Co-HTC temperature and the oxidation reaction during the Co-HTC on the decomposition behaviors were investigated. The percentage decomposition in nitrogen atmosphere increased with increasing the reaction temperature and reached 76.1% at 260oC. The percentage decompositions in nitrogen were several percent higher than those in air. The synergistic effect of PVC and WC for the decomposition was observed at 220oC in N2. When the Co-HTC was performed in air, decomposition was suppressed, indicating the increase in hydrochar yield. The dechlorination yield was determined from the Cl content in the recovered PVC after the Co-HTC reaction. Under nitrogen atmosphere conditions, the dechlorination yield increased slightly with increasing the temperature. At a carbonization temperature of 260oC, the dechlorination yield of PVC was about 40%.

Co-CoOx supported onto TiO2 coated with carbon as a catalyst for efficient and stable hydrogen generation from ammonia borane

Ammonia borane (AB) can be catalytically hydrolyzed to provide hydrogen at room temperature due to its high potentaial for hydrogen storage. Non-precious metal heterogeneous catalysts have broad application in the field of energy catalysis. In this article, catalysts precursor is obtained from Co-Ti-resorcinol-formaldehyde resin by sol–gel method. Co/TiO2@N-C (CTC) catalyst is prepared by calcining the precursor under high temperature conditions in nitrogen atmosphere. Co-CoOx/TiO2@N-C (COTC) is generated by the controllable oxidation reaction of CTC. The catalyst can effectively promote the release of hydrogen during the hydrolytic dehydrogenation of AB. High hydrogen generation at a specific rate of 5905 mL min−1 gCo−1 is achieved at room temperature. The catalyst retains its 85% initial catalytic activity even for its fifth time use in AB hydrolysis. The synergistic effect among Co, Co3O4 and TiO2 promotes the rate limiting step with dissociation and activation of water molecules by reducing its activation energy. The applied method in this study promotes the development of non-precious metals in catalysis for utilization in clean energy sources.

Anhydrous proton conductive xCHS-(1-x)WSiA composites prepared via liquid-phase shaking

High proton conductive xCsHSO4-(1-x)H4SiW12O40(CHS-WSiA) composites were successfully prepared via a new liquid-phase shaking method. N,N‑Dimethylacetamide (DMAc) and zirconium balls were used as a solvent/dispersing medium and a collision medium, respectively. X-ray diffraction characterization confirmed that the liquid-phase shaking treatment induced an ion-exchange reaction between Cs+ ions in CHS and H+ ions in WSiA to form new composite materials. The proton conductivities of these composites were significantly improved over their precursor materials, especially at low temperatures, below the superprotic phase-transition temperature of CHS. The 0.9CHS-0.1WSiA (in mole ratio) composite, for instance, showed the highest proton conductivities of 1.38 × 10−4 to 2.42 × 10−3 S cm−1 from 50 °C to 170 °C under dry conditions of nitrogen atmosphere. The enhanced anhydrous proton conductivities of the Cs-substituted WSiA composites were also corroborated with shortening of the hydrogen bonding distance in these composites for fast proton hopping transport mechanism via 1H NMR evaluation.

Thermal stability of phosphorus-containing epoxy resins by thermogravimetric analysis

The thermal stabilities of epoxy resin/diethyl bis(2-hydroxyethyl)aminomethylphosphonate (EP/DBAMP) systems were investigated by thermogravimetric analysis (TGA) under non-isothermal conditions in nitrogen atmosphere. Kissinger and Flynn–Wall–Ozawa methods were used to study the thermal degradation process. The results showed a remarkable increase of activation energy ( E) in the presence of DBAMP, which indicated that the addition of DBAMP retarded the thermal degradation of EP. The Flynn–Wall–Ozawa analysis further revealed that DBAMP significantly increased the activation energy in the early stage of EP’s thermal degradation, demonstrating that DBAMP had improved the initial thermal stability and modified the flame retardancy of EP in the thermal degradation process.

Residual free solder process for fluxless solder pastes

Purpose For soldering, flux is essential because it enables the wetting of the molten solder. Fluxless soldering, i.e. residue-free soldering with the aid of gaseous activators, has been known for many years, but is only well established in the field of opto- and microwave electronics where the solder is applied as preform. In high-volume SMD applications where solder paste is printed, this technology is rarely used until now. The reducing effect of a gaseous activator like formic acid vapor on certain solder alloys is known in practice. However, the corresponding reactions which occur under soldering conditions in nitrogen atmosphere have so far not been systematically investigated for different solder alloys. This study aims to analyze the different chemical reaction channels which occur on the surface of different solders, i.e. catalytical dissociation of formic acid on the pure or oxidized metal surface and the formation and evaporation of metal formates. Based on this analysis, a residue-free solder process under formic acid is developed for solder paste applications. Design/methodology/approach In this paper, different solder alloys (SnAgCu, SnPb, BiSn, In) were analyzed with thermal gravimetric analysis (TGA) under formic acid flow. Details on mass change depending on the soldering temperature are presented. Activation temperatures are estimated and correlated to the soldering processes. Based on the analysis, fluxless solder pastes and suitable soldering processes are developed and presented. Major paste properties such as printability are compared to a commercial flux solder paste. High-power flip chip LEDs which can be assembled directly on a printed circuit board are used to demonstrate the fluxless soldering. Likewise, the soldering results of standard paste and fluxless paste systems after a reflow process are evaluated and compared. Findings The experimental results show that TGA is an efficient way to gain deeper understanding of the redox processes which occur under formic acid activation, i.e. the formation of metal formates and their evaporation and dissociation. It is possible to solder residue-free not only with preforms but also with a fluxless solder paste. The resulting solder joints have the same quality as those for standard solder paste in terms of voids detected by X-ray and mechanical shear strength. Originality/value In the fluxless soldering process, the reduction of oxide layers, and therefore the wetting of the solder spheres, is enabled by gaseous formic acid. After the soldering process, no cleaning process is necessary because no corrosive residues are left on the circuit boards and components. Therefore, soldering using solder paste without aggressive chemical ingredients has a high market potential. Expensive preforms could be replaced by paste dispensing or paste printing.

Thermal decomposition kinetics of some transition metal coordination polymers of fumaroyl bis (paramethoxyphenylcarbamide) using DTG/DTA techniques

In the present work, thermal degradation behaviors of the Zn (II), Cd(II), and Hg(II) coordination polymers of fumaroyl bis (paramethoxyphenylcarbamide) (fbpmpc) have been investigated by using thermogravimetric (TG) analysis, differential thermal analysis (DTA) and derivative thermogravimetry (DTG) analysis under non-isothermal conditions in nitrogen atmosphere at multiple heating rates. TG–DTA study noteworthy inferred the presence of lattice water in outer sphere of all the polymers. The decomposition was carried out in three-four well-separated stages where involved the loss of water molecules in the first step followed by organic ligand. Furthermore, the kinetics and thermodynamic stabilities of multi-steps thermal degradation were evaluated. The activation energy (Ea), order of reaction (n), Arrhenius factor (A), enthalpy change (ΔH), entropy change (ΔS) and free energy change (ΔG) of coordination polymers were obtained by using the Coats–Redfern (CR) method. Ultimately, based on initial, half and final decomposition temperature, and kinetics parameters values the orders of thermal stability were estimated.

Co‐pyrolysis characteristics of coal and sludge blends using thermogravimetric analysis

Co‐pyrolysis characteristics of low grade coal (LGC) and sludge derived fuel (SDF) as well as their blends (L/S = 85/15, 75/25, 50/50, and 25/75) were determined at nonisothermal (10, 20, and 30°C/min) conditions in nitrogen atmosphere using thermogravimetric analyzer (TGA). The results indicated that SDF decomposed at a lower temperature than LGC and weight loss of L/S blends was lower than individual LGC or SDF. The difference of weight loss between experimental measurement and theoretical calculation reached circa 0.82 to 2.50 wt % at around 900°C, indicating that there was an inhibitive effect between LGC and SDF. In addition, textural analysis also confirmed the assumption that L/S blend char had higher surface area but less micropore. The results of kinetics analysis showed that the process could be described by two or three consecutive first order reactions, which revealed the possible mechanism of co‐pyrolysis behaviors between LGC and SDF. The estimated kinetics parameters (activation energies and pre‐exponential factors) for LGC, SDF and their blends were found to be in the range of 16.3 to 144.1 kJ/mol and 1.21 to 4.09 × 1010 min−1, respectively. Lower activation energies observed in the relevant decomposition stages indicated that the reaction became faster upon blending. © 2015 American Institute of Chemical Engineers Environ Prog, 34: 1780–1789, 2015

Properties of the CdCl2 Air-annealed CSS CdTe Thin Films

Thin 7-9μm CdTe films have been deposited on soda lime glass by close-spaced sublimation (CSS). By controlling the CSS temperature-time profile of source and substrate the pinhole-free CdTe films with a good adhesion on roughened glass were prepared. The classical solution-based CdCl2 was applied to enhance the film crystallinity and optoelectronic properties of the CdTe layers. The layers were characterized by X-ray diffraction, Raman and Photoluminescence spectroscopy, scanning microscopy (SEM), energy dispersive X-ray microanalysis and Van der Paw method. CdCl2 heat treatment is a key step in CdTe device processing. Howeverthe process leaves a significant amount of chlorine-rich residue on the CdTe surface that decreases performance of the solar cell.Annealing of the CdCl2-treated polycrystalline CdTeimproves the optoelectronic properties and thus enhances the performance of CdTe/CdS solar cells. A correlation between the structural and optoelctronic properties of CdTe layers and annealing conditions in nitrogen atmosphere at 250, 400 and 450oC for 60min of the CdCl2treated layers has been found.

Recyclable and reusable nano-CuFe2O4 catalyzed C-O cross-coupling

An efficient protocol was developed and validated for the synthesis of biaryl/aryl alkyl ethers using CuFe 2 O 4 nano powder as a recyclable catalyst via the reaction between aryl halides and phenols/alcohols. Variety of aryl ethers were synthesized efficiently in the presence of catalytic amount of CuFe 2 O 4 , KOH as base, under ligand free conditions in nitrogen atmosphere with DMSO as solvent at 120 o C. The catalyst is air-stable, inexpensive, magnetically separable and recyclable up to four cycles.

Nonisothermal degradation kinetics for epoxy resin systems containing polymethylphenylsilsesquioxane

AbstractThe thermal degradation behaviors of polymethylphenylsilsesquioxane/epoxy resin (PMPSQ/EP) systems were investigated by thermogravimetric analysis (TGA) under nonisothermal conditions in nitrogen atmosphere. During nonisothermal degradation, Kissinger's and Flynn‐Wall‐Ozawa's methods were both used to analyze the thermal degradation process. The results showed that a remarkable increase of activation energy was observed in the presence of PMPSQ, which indicated that the addition of PMPSQ retarded the thermal degradation of EP. Flynn‐Wall‐Ozawa's method further revealed that PMPSQ significantly increased the activation energy of EP thermal degradation especially in the early and final stage of thermal degradation process, which illustrated that the PMPSQ stabilized the char layer and improved the flame retardancy of EP. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Thermal degradation of rice-bran with high density polyethylene: A kinetic study

Thermal degradation behavior of mixtures of rice bran (RB) and high density polyethylene (HDPE) was investigated by thermo-gravimetric analyses (TGA) under dynamic conditions in nitrogen atmosphere and was compared with that of individual materials. Experiments were carried out in the range of ambient temperature to 900 °C at two heating rates (5 and 20 °C per minute). Kinetic analysis indicated that activation energy for pyrolysis of RB, HDPE and those for RB-HDPE mixtures varied with rate of heating as well as with the three temperature ranges. This variation has been explained on the materials’ decomposition behavior. Maximum difference between experimental and theoretical mass loss (Δm) was 26% at 475 °C and 34% at 489 °C at the heating rates of 5 and 20 °C per minute, respectively. These maxima indicate stronger interactions at corresponding temperature between RB and HDPE during copyrolysis. Reduction in activation energy for pyrolysis, lower temperatures at which rate of decomposition is highest, and negligible quantity of the residue suggest a synergism between thermal degradation of RB and HDPE.

Non-isothermal degradation kinetics for polycarbonate/ polymethylphenylsilsesquioxane composites

AbstractThe thermal degradation behaviors of PC/PMPSQ (polymethylphenylsilsesquioxane) systems were investigated by thermogravimetric analysis (TGA) under non-isothermal conditions in nitrogen atmosphere. During non-isothermal degradation, Kissinger and Flynn-Wall-Ozawa methods were used to analyze the thermal degradation process. The results showed that a remarkable decrease in activation energy ( E ) was observed in the early and middle stages of thermal degradation in the presence of PMPSQ, which indicated that the addition of PMPSQ promoted the thermal degradation of PC. Flynn-Wall-Ozawa method further revealed that PMPSQ significantly increased the activation energy of PC thermal degradation in the final stage, which illustrated that the PMPSQ stabilized the char residues and improved the flame retardancy of PC in the final period of thermal degradation process

Differential thermal analysis of porous silicon

Porous silicon materials, macro- and mesoporous silicon, obtained by electrochemical anodic etching of n- and p-Si were studied by differential thermal analysis at a steady temperature rise and under isothermal conditions in nitrogen atmosphere and in air. The method was used to estimate the presence and amount of phases of surface volatile compounds. The possibility was studied to perform a comparative estimate of the specific surface area of different types of porous silicon from data on the surface oxidation kinetics determined by the dynamic differential thermal analysis in air.

Thermal degradation kinetics and lifetime estimation for polycarbonate/polymethylphenylsilsesquioxane composite

The thermal degradation behaviors of polycarbonate/polymethylphenylsilsesquioxane (FRPC) composites were investigated by thermogravimetric analysis (TGA) under isothermal conditions in nitrogen atmosphere. The isothermal kinetics equation was used to describe the thermal degradation process. The results showed that activation energy (E), in the case of isothermal degradation, was a quick increasing function of conversion (α) for polycarbonate (PC) but was a strong and decreasing function of conversion for FRPC. Under the isothermal condition, the addition of polymethylphenylsilsesquioxane (PMPSQ) retardanted the thermal degradation and enhanced the thermal stability of PC during the early and middle stages of thermal degradation. It also indicated a possible existence of a difference in nucleation, nuclei growth, and gas diffusion mechanism in the thermal degradation process between PC and FRPC. Meanwhile, the addition of PMPSQ influenced the lifetime of PC, but the composite still met the demand in manufacturing and application.

Pyrolysis and combustion of waste lubricant oil from diesel cars: Decomposition and pollutants

Pyrolysis and combustion of waste lubricant oil were studied due to its important potential value as a fuel. A thermogravimetric analysis in nitrogen atmosphere conditions and with different proportions of nitrogen:oxygen (N 2, N 2:O 2 mixtures at 4:1 and 9:1 ratios), different weights (1, 2.5 and 5 mg) and different heating rates (5, 10 and 15 °C min −1) were carried out to study the thermal decomposition. Both pyrolysis and combustion can be represented in two processes: in the first process, a volatilization of the oil takes place (this depends on the initial mass and the heating rate) and in the second process there is a decomposition, which is a different process in combustion from the process in pyrolysis. The identification of the volatile and semivolatile compounds from pyrolysis and combustion of used diesel oil was carried out in a tubular reactor at 500 and 850 °C. On the one hand, the semivolatile PAH compounds (naphthalene, phenanthrene, anthracene, etc.) were detected as much in pyrolysis as in combustion (850 °C), but the most highly carcinogenic is benzo(a)pyrene which was only found in pyrolysis at 850 °C. On the other hand, the levels of PCDD/Fs and dioxin-like PCBs were estimated after a fuel-rich combustion process at around 113 pg WHO-TEQ g −1 burnt oil (corresponding to 80 pg I-TEQ g −1) and 3 pg WHO-TEQ g −1 burnt oil, respectively. The PCDD/Fs concentration in the raw sample was estimated at around 7–16 pg WHO-TEQ g −1 used oil (or 6–13 pg I-TEQ g −1) and PCBs were not detected.

An Experimental Study on Pyrolysis of Biomass

In this study, pyrolysis of sugarcane bagasse was performed in fixed bed tubular reactor under the conditions of nitrogen atmosphere, by varying temperature and different particle sizes. The effect of final pyrolysis temperature from 400 to 500°C and the nitrogen flow rate from 50 to 200ccmin−1 on the pyrolysis product yields from sugarcane bagasse have been investigated. The Maximum bio-oil yield obtained is 24.12wt% at the final pyrolysis temperature of 450°C, N2 flow rate of 50ccmin−1 and particle size of mesh number −8+12. The yield of bio-oil decreases with increase in temperature from 450 to 550°C and N2 flow rate from 50 to 200ccmin−1. The various characteristics of pyrolysis oil obtained under these conditions were identified on the basis of standard test methods. The empirical formula of pyrolysis oil with a heating value of 37.01MJKg−1 was established as CH1.434 O0.555 N0.004. The results from the pyrolysis show the potential of sugarcane bagasse as an important source of liquid hydrocarbon fuel.

Photochemical Production of Biphenyls from Oxidized Sulfur Compounds Obtained by Oxidative Desulfurization of Light Oils

Photochemical production and recovery process of biphenyls from the desulfurization products, obtained by oxidative desulfurization (ODS) of light oils, has been investigated. The S-oxidized dibenzothiophenes (DBT sulfones), when dissolved in 2-propanol, were converted successfully into the corresponding biphenyls by photoirradiation at wavelengths of λ > 280 nm using a high-pressure mercury lamp, under conditions of nitrogen atmosphere and at room temperature. The present photochemical process was found to be also effective for the production of biphenyls from the DBT sulfones present in the desulfurization products of low-aromatic-content light oils. The quantitative recovery of biphenyls from the resulting 2-propanol solution was carried out successfully by adsorption using neutral aluminum oxide and subsequent elution with dichloromethane/n-hexane (20/80 v/v) mixture.

Effect of mineral matter on the combustion curve of chars

In this study, the effect of mineral matter content on the combustion curve of the chars produced from 25 lignite samples originating from different parts of Turkey was investigated using differential thermal analysis (DTA). During the DTA studies, original and demineralized lignite samples were carbonized under identical conditions in nitrogen atmosphere up to 1423 K and, after cooling to the room temperature under nitrogen flow, they were heated at a constant rate of 40 K min −1 in flowing air up to 1273 K. The DTA combustion curves of the char samples produced from the original and demineralized lignites and their heat release rates are compared and discussed. It was observed that the shapes of the DTA combustion curves of the chars were strongly affected by the demineralization process. In particular, the burn-out times and the heat release rates changed markedly.