Showing papers on "Thermal decomposition published in 2020"
TL;DR: A low-cost polymer/glass stack encapsulation scheme that enables PSCs to pass the demanding International Electrotechnical Commission (IEC) 61215:2016 Damp Heat and Humidity Freeze tests is reported.
Abstract: INTRODUCTION Although advances in materials and processing have led to remarkable advancements in the energy conversion efficiency of perovskite solar cells (PSCs), increasing from 3.8% to 25.2% in only 10 years, these solar cells cannot become commercially viable unless their underperforming durability is improved. The instability of perovskites must be addressed if PSCs are to compete with silicon technology, which currently offers a 25-year performance warranty. Previous approaches to this problem include the use of metal oxide barrier layers and butyl rubber sealants. Here, we report a low-cost polymer/glass stack encapsulation scheme that enables PSCs to pass the demanding International Electrotechnical Commission (IEC) 61215:2016 Damp Heat and Humidity Freeze tests. These tests help to determine whether solar cell modules can withstand the effects of outdoor operating conditions by exposing them to repeated temperature cycling (–40° to 85°C) as well as 85% relative humidity. Our airtight encapsulation scheme prevented moisture ingress. It was also effective in suppressing outgassing of decomposition products, which limits decomposition reactions of organic hybrid PSCs by allowing these reactions to come to equilibrium. The gas compositions were verified by gas chromatography–mass spectrometry (GC-MS). RATIONALE In the GC-MS technique, gas chromatography separates the components in a mixture, and the chemical identity of each component is determined with mass spectrometry. We could directly identify with high specificity the decomposition products of multi-cation perovskite precursors, of unencapsulated perovskite test structures, and of encapsulated full cells at elevated temperatures. The results allowed us to identify thermal degradation pathways by determining the outgassing products of mixed-cation perovskites during heating. We then used GC-MS to evaluate the effectiveness of different packaging techniques developed for PSCs. The packaging schemes were a polyisobutylene (PIB)–based polymer blanket encapsulation, a polyolefin-based blanket encapsulation, and a PIB edge seal. These packaging layers were then capped by a glass cover. For the edge seal, the decomposition gases inside the cell were sampled with a syringe. The feasibilities of these packaging techniques were also demonstrated by IEC photovoltaic module standard Damp Heat and Humidity Freeze testing. RESULTS Signature decomposition products such as CH3I, CH3Br, and NH3 were identified and decomposition pathways were proposed for CH3NH3I (MAI), HC(NH2)2I (FAI), CH3NH3Br (MABr), and mixed-cation and mixed-halide (FAI)0.85 + (MABr)0.15 perovskite precursors, including their secondary decomposition reactions at 350°, 140°, and 85°C. The GC-MS results confirmed that the Br-containing precursor was less prone to thermal decomposition than an I-containing precursor. Also, CsFAMA cells were found to outgas one-fifth as much decomposition product as their FAMA counterparts, which indicated that the Cs-containing cells had better thermal stability. Although the decomposition of FAI is reversible, the mixing of MA with FA precursors caused decomposition products to participate in the secondary reaction that was irreversible. This finding confirmed the disadvantage of mixing of MA with FA perovskite through the reduction in chemical stability. The blanket-encapsulated PSCs sustained no efficiency degradation after 1800 hours of Damp Heat testing or 75 cycles of Humidity Freeze testing. CONCLUSION GC-MS identified signature volatile products of the decomposition of organic hybrid perovskites under thermal stress, thereby informing decomposition pathways. The findings are important for developing potential cell-stabilizing strategies, given that cells in the field typically experience high operating temperatures. In addition, results of GC-MS confirm that the low-cost pressure-tight encapsulation we developed is effective in suppressing such outgassing and therefore decomposition reactions of PSCs. This encapsulation scheme is the simplest of all for perovskite cells to pass IEC photovoltaic module standard tests. Our approach can be applied to evaluating the effectiveness of other packaging approaches, as well as testing the effectiveness of coatings and material compositions aimed at limiting light and thermal degradation.
290 citations
TL;DR: In this paper, a series of hierarchical micro/nano Ce-based composites were derived from Ce-MOF via thermal treatment in N2 atmosphere, and the results implied a predominant effect of different valence states on phosphate removal by Cebased materials, in which Ce(III) species were demonstrated playing the major role to form binding with phosphate.
144 citations
TL;DR: In this article, a critical review of thermogravimetric analysis (TGA) data from the metal-organic frameworks (MOF) literature, and question the consistency, accuracy and meaning of the data provided.
129 citations
TL;DR: In this article, the thermal decomposition mechanisms of energy-rich materials have been investigated experimentally and theoretically for decades, but there are still many unanswered questions concerning their thermal decompositions.
Abstract: Energetic materials have been widely investigated experimentally and theoretically for decades, but there are still many unanswered questions concerning their thermal decomposition mechanisms that ...
100 citations
TL;DR: The catalytic effect of K2SiF6 on MgH2 was first timely studied in this paper, where the authors showed that the catalyst had lessened the initial decomposition temperature by 134 °C and 48 °C as compared to both pristine and milled Mg H2 samples, respectively.
99 citations
TL;DR: In this article, a series of novel ionic liquids (ILs) were used as chemical inhibitors for coal spontaneous combustion (CSC) by using Fourier transform infrared spectroscopy and synchronous thermal analyser.
73 citations
TL;DR: In this article, the potential of microporous 3D metal-organic framework (MOF) for curing epoxy resin has been discussed, and their curability was studied in terms of the universal dimensionless cure index (CI) criterion under nonisothermal differential scanning calorimetry (DSC).
65 citations
TL;DR: In this paper, the effect of thermal cycling on the thermophysical properties, such as phase transition temperature, latent heat, chemical compatibility, thermal stability and thermal conductivity, was studied.
64 citations
TL;DR: Dimethyl sulfoxide (DMSO) is widely used as a solvent for chemical reactions, as a cosolvent for crop protection formulations, and in medicines for topical administration of drugs.
61 citations
TL;DR: In this paper, the authors used nano-TiO2 particles to improve the thermal properties of paraffin by embedding them in the material and further investigated on their thermal properties using different instruments such as Fourier transform infrared spectrometer (FT-IR), thermogravimetric analyzer (TGA), thermal properties analyzer.
59 citations
TL;DR: A series of bi-metallic layered double hydroxide derived materials, containing a fixed amount of Ni promoted with various amounts of Fe were obtained by co-precipitation as discussed by the authors.
TL;DR: In this article, co-pyrolysis of Miscanthus Sacchariflorus (MS) and three ranks of coal, namely lignite (LC), bituminous coal (BC), and anthracite (AC), was performed at the analytical scale.
TL;DR: It is discovered that the preferred channel for PFOS decomposition is via an α-sultone that spontaneously decomposes to form perfluorooctanal and SO2, and results show that the acid headgroup in PFOS can be efficiently destroyed in incinerators operating at relatively modest temperatures.
TL;DR: In this paper, a detailed stepwise investigation of the increasing reactivity of 532, 622, 811 and 901 NMC materials towards a specific H2O/CO2 atmosphere is reported.
TL;DR: In this article, α-Fe2O3 nanoparticles were successfully prepared by a simple and direct hydrothermal method using three different precursors (iron chloride, iron nitrate and iron sulphate).
TL;DR: In this paper, the microwave assisted graphitic carbon nitride/CuO (m-g-C3N4/cuO) nanocomposite was synthesized through microwave pretreatment and mixing-calcination.
TL;DR: In this article, a single-step thermal decomposition procedure to produce carbon-doped SnO2 nanostructures (C-SnO2) for photocatalytic applications is proposed.
TL;DR: In this article, the thermal decomposition and combustion performance of ammonium perchlorate (NH4ClO4, AP)-based molecular perovskite materials (H2dabco) were investigated by X-ray diffraction and Fourier transform infrared (FT-IR).
TL;DR: The solution-freeze-drying technology is simple and easy to control, providing a new strategy for the preparation of ultra-low density metal oxide aerogels with good formation ability and great potential application in thermal insulation, adsorption and catalyst supports.
TL;DR: E-cigarette users must know that hazardous substances are generated even within the recommended electric power limits, as thermal decomposition products of e-liquid, acetaldehyde, acrolein, and propylene oxide mainly occur as gaseous matter, while glyoxal, methylglyoxal
Abstract: An electronic cigarette (e-cigarette) is a product used to smoke aerosol by heating a solution of "e-liquid" that consists of propylene glycol (PG) and glycerol (GLY) containing nicotine and flavors. In this study, thermal decomposition products generated from three brands of e-cigarettes were determined at various electric power levels. When using neat PG or GLY instead of e-liquid, propylene oxide was detected only in the gas phase from PG and not detected from GLY. In contrast, glycidol was detected only from GLY and not from PG. Almost all of the glyoxal and acrolein was detected from GLY, but formaldehyde and methyl glyoxal were detected from both PG and GLY. Using commercially available e-liquids, the same results were obtained. Nearly all chemical compounds generated from e-cigarettes have a carbon number of 3 or less except for nicotine and flavors. We measured chemical compounds generated from e-cigarettes at various electric power levels (1-85 W). At an electric power of 10 W, the generation of chemical compounds was very low; however, when the electric power exceeded 40 W, it increased exponentially. As thermal decomposition products of e-liquid, acetaldehyde, acrolein, and propylene oxide mainly occur as gaseous matter, while glyoxal, methylglyoxal, and glycidol mainly occur as particulate matter. Formaldehyde exits in both gaseous and particulate matter forms. Thermal decomposition products can be divided into three groups: thermal decomposition products originating from PG and GLY, those originating from other sources, and those directly generated. Concentrations of these thermal decomposition products were mostly higher than those in traditional cigarettes. In particular, thermal decomposition products generated from one of the studied e-cigarettes were very high; e.g., formaldehyde reached 4400 μg/15 puffs at 50 W. E-cigarette users must know that hazardous substances are generated even within the recommended electric power limits.
TL;DR: In this article, four different perovskites, namely LaCoO3, La2CuO4, LaMnO3 and LaNiO3 were prepared by co-precipitation method and then applied to catalyze the AP decomposition.
TL;DR: Wang et al. as discussed by the authors compared the properties and added value of Chinese fir wood by respiratory impregnation method, and showed that the weight percentage gain, density growth rate, bending strength, compressive strength, and dimensional stability of SSMCF were clearly higher than those of PFOMCF.
Abstract: To improve the properties and added value of Chinese fir wood, sodium silicate-modified Chinese fir wood (SSMCF) was prepared by respiratory impregnation method. Phenol formaldehyde oligomer-modified Chinese fir wood (PFOMCF) as control sample, the impregnation and reinforcement effects, water resistance of PFOMCF and SSMCF were compared. The results showed that the weight percentage gain, density growth rate, bending strength, compressive strength, and dimensional stability of SSMCF were clearly higher than those of PFOMCF, and the SSMCF showed a lower water absorption rate within 60 h. The impregnation and reinforcement effects, for SSMCF were better than those for PFOMCF. FT-IR, XRD, CONE, and TGA examinations were used to analyze the chemical structure, crystalline structure, flame retardancy, and heat resistance of these modified woods. The results indicated that Si O Si chemical bonding with high bond energy was formed in SSMCF, and there are possessed more hydrogen bonds in SSMCF than PFOMCF and that Si O Si chemical bonding with high bond energy was formed. Meanwhile, the weakened degree of the diffraction peak of SSMCF was much less than that of PFOMCF. These results explained the better mechanical properties and water resistance of SSMCF. Compared with PFOMCF, SSMCF had lower heat release rate (HRR), peak-HRR, mean-HRR, total heat release, smoke production rate, and total smoke production, and showed higher thermal decomposition temperature and residual rate. Inorganic sodium silicate was shown to be a better flame retardant, while SSMCF had good smoke suppression effects, thermal stability, and safety performance in the case of fire.
TL;DR: In this paper, pyrolysis processes of 11 typical hydrocarbons (isobutane, isopentane, isohexane, n-butane and toluene) are performed by using ReaxFF MD and DFT method.
TL;DR: New insights are provided into the preparation of desired composite catalysts with excellent performances and the synergistic mechanism of the catalyst was explored by XRD, Raman, BET, TEM, and XPS.
Abstract: A novel core–shell (e-MnO2/CeO2)@CeO2 composite catalyst with a synergistic effect was prepared by hydrothermal reaction and thermal decomposition and its application to high-efficiency oxidation r...
TL;DR: Thermodynamic parameters and reactive hydroxyl groups in this article review are innovative and have not yet been found in the literature.
Abstract: The main aim of this study is to estimate the kinetic and thermodynamic parameters of thermal decomposition of starches by the Coats–Redfern method. This procedure is a commonly used thermogravimetric analysis/difference thermal gravimetry/differental thermal analysis (TG/DTG-DTA) kinetic method for single rate form. The study also shows a proposed method for reactive hydroxyl groups content on the starch surface determination, and values were in range of 960.21–1078.76 mg OH per 1 g of starch. Thermal processing revealed the thermophysical properties of biomass for the kinetics of decomposition estimation. Activation energies reached the values in range of approximately 66.5–167 kJ·mol−1. This research also enables the determination of the temperature conditions required for becoming the desired form of material. Therefore, it is necessary to achieve the requested compact porous structure in an activation process, because in the native state, the polymer exhibits limited applications as a result of thermal decomposition, low shear stress, retrogradation, and syneresis, hence the low solubility in organic solvents. Thermodynamic parameters and reactive hydroxyl groups in this article review are innovative and have not yet been found in the literature.
TL;DR: In this article, the structure and morphology of MnO2/MXene@C composite were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and Xray photoelectron spectra (XPS).
TL;DR: In this article, the phase stability of SmFe12-based compounds was investigated by experimental and computational first-principles approaches and the effect of particle size and alloy composition on the thermal decomposition rate was addressed.
TL;DR: In this article, the hazards associated with thermally abused LiNiNi1/3Co 1/3Mn/3O2/graphite batteries at different state of charges (SOCs) are experimentally assessed.
Abstract: Temperature response, thermal decomposition, and gas generation are important metrics for evaluating thermal runaway hazards of lithium-ion batteries. In this paper, the hazards associated with thermally abused LiNi1/3Co1/3Mn1/3O2/graphite batteries at different state of charges (SOCs) are experimentally assessed. The results show that the maximum temperature of the battery during thermal runaway increases linearly with SOC, which is also accompanied by a linear decrease of the thermal runaway onset temperature. In addition, %%both the 90% and the 100% SOC batteries experienced some degree of gas deflagration and particle ejection that generated 1.22 g and 2.57 g of powders, respectively. While these powders are mostly contributed by the decomposition of battery cathodes, the gas deflagration can be mainly attributed to sparks that ignited the flammable gases released from the thermally abused batteries. Furthermore, this research also establishes a complete list of gas components observed at different SOCs, and the flammable ones are mainly carbon oxides, hydrocarbons, C2H4O2, and C2H6O. It is also observed that an increasing number of gas types will be generated at higher SOCs%, and some of these new components such as benzene can be harmful and toxic to the environment. Finally, this complete list of gas components can be used to identify characteristic gas types for an early warning mechanism of thermal runaway, which can be accomplished by installing appropriate gas sensors and monitoring their volume concentrations.
TL;DR: It is demonstrated that Fe2O3-CMS have a minor influence on the decomposition temperature of NC, while a noticeable diminution of the activation energy is acquired, and it can infer that Fe1O2-C MS may be securely employed as an effective catalyst for the thermal decomposition of NC.
Abstract: In this study, carbon mesospheres (CMS) and iron oxide nanoparticles decorated on carbon mesospheres (Fe2O3-CMS) were effectively synthesized by a direct and simple hydrothermal approach. α-Fe2O3 nanoparticles have been successfully dispersed in situ on a CMS surface. The nanoparticles obtained have been characterized by employing different analytical techniques encompassing Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The produced carbon mesospheres, mostly spherical in shape, exhibited an average size of 334.5 nm, whereas that of Fe2O3 supported on CMS is at around 80 nm. The catalytic effect of the nanocatalyst on the thermal behavior of cellulose nitrate (NC) was investigated by utilizing differential scanning calorimetry (DSC). The determination of kinetic parameters has been carried out using four isoconversional kinetic methods based on DSC data obtained at various heating rates. It is demonstrated that Fe2O3-CMS have a minor influence on the decomposition temperature of NC, while a noticeable diminution of the activation energy is acquired. In contrast, pure CMS have a slight stabilizing effect with an increase of apparent activation energy. Furthermore, the decomposition reaction mechanism of NC is affected by the introduction of the nano-catalyst. Lastly, we can infer that Fe2O3-CMS may be securely employed as an effective catalyst for the thermal decomposition of NC.
TL;DR: In this article, a high-fitting degree was obtained for isothermal and non-isothermal DSC experiments of cellulose nitrate, and the model corresponding to isothermal conditions was f(α) = 4(1 − α)[−ln( 1 − α)]3/4, while for nonisothermal conditions the model was identified as f( α) = (1 −α)3.