Low-temperature Thermal Decomposition Research Articles

Preparation of Y3+ and transition metal ions codoped-BiFeO3 with enhanced magnetism and photocatalytic properties

Nanosized particles of Bi 0.95 Y 0.05 Fe 0.97 M 0.03 O 3 (M ​= ​Mn,Co,Ni,Cu,Zn) were successfully synthesized through thermal decomposition coordination precursors with diethylenetriaminepentaacetic acid (H 5 dtpa) as ligand. All prepared samples were characterized by XRD, Uv–vis DRS, SEM, PL, EIS, VSM and so on. From XRD results, the main phase of the samples was rhombohedral R3c (161) BiFeO 3 , and contained a small amount of soft iron ore Bi 25 FeO 40 . The phase and morphology of prepared samples were affected by doping ions. The average grain size of the samples was about 20 ​nm.T.The Uv–vis demonstrated the band gap of all samples was less than 2 ​eV and the response to light of all samples extended from ultraviolet region to visible region (~650 ​nm).The BFO–Y–Mn exhibited the minimum band gap of 1.77 ​eV. At the same time, photocatalytic activities of all samples prepared were evaluated through the photocatalytic degradation of methyl orange (MO). BiFeO 3 co-doping with 5%Y 3+ and 3%Mn 2+ exhibited excellent photocatalytic activity for MO solution. In the present of BFO–Y–Mn, the degradation rate of MO under light irradiation of 3 ​h was about 98%. Y 3+ ion and transition metal ions co-doped bismuth ferrite were successfully prepared by low-temperature thermal decomposition of coordination precursor method. The effects of different transition metal ions on the phase, magnetism, band structure, and photocatalytic properties of BiFeO 3 have been investigated. According to the energy band potential, it can be inferred that •OH − is the main active species in the photodegradation reaction of MO. • Y 3+ and M 2+ co-doped BiFeO 3 photocatalysts were successfully synthesized by a facile method. • Y 3+ and M 2+ co-doped BiFeO 3 photocatalysts demonstrated residual magnetism at room temperature. • The phase, band structure, and photocatalytic properties of co-doped BiFeO 3 ​have been investigated.

Formation Mechanism of β-Li3PS4 through Decomposition of Complexes.

β-Li3PS4 is a solid electrolyte with high Li+ conductivity, applicable to sulfide-based all-solid-state batteries. While a β-Li3PS4-synthesized by solid-state reaction forms only in a narrow 300-450 °C temperature range upon heating, β-Li3PS4 is readily available by liquid-phase synthesis through low-temperature thermal decomposition of complexes composed of PS43- and various organic solvents. However, the conversion mechanism of β-Li3PS4 from these complexes is not yet understood. Herein, we proposed the synthesis mechanism of β-Li3PS4 from Li3PS4·acetonitrile (Li3PS4·ACN) and Li3PS4·1,2-dimethoxyethane (Li3PS4·DME), whose structural similarity with β-Li3PS4 would reduce the nucleation barrier for the formation of β-Li3PS4. Synchrotron X-ray diffraction clarified that both complexes possess similar layered structures consisting of alternating Li2PS4- and Li+-ACN/DME layers. ACN/DME was removed from these complexes upon heating, and rotation of the PS4 tetrahedra induced a uniaxial compression to form the β-Li3PS4 framework.

A Review and Update of Bubble Column Evaporator Processes

This paper gives an updated review of the bubble column evaporator (BCE) and its various new processes. These include recent work on helium gas desalination and high temperature inlet gas decomposition. The BCE process offers a continuously produced source of high gas-water interface and consequently provides high overall heat and mass transfer coefficients. Very different results have been obtained using nitrogen, oxygen, carbon dioxide and helium inlet gases. Although the bubbling process itself is both simple to use and apply, our understanding of the fundamental physical and chemical principles involved is surprisingly limited and there are many issues yet to be explained. Recently the process has been used to develop new methods for the precise determination of enthalpies of vaporisation of concentrated salt solutions, as an evaporative cooling system, a sub-boiling thermal desalination unit, for sub-boiling thermal sterilization, for low temperature thermal decomposition of different solutes in aqueous solution and for the inhibition of particle precipitation in supersaturated solutions. These novel applications can be very useful in many industrial practices, such as desalination, water/wastewater treatment, thermolysis of ammonium bicarbonate (NH4HCO3) for the regeneration in forward osmosis and refrigeration related industries. The background theories and models use to explain the BCE process are also reviewed and this fundamental knowledge is applied to the design of BCE systems and to explain recently explored applications, as well as potential improvements. Many other prospective applications of the BCE process are also reported in this paper.

FTO-free and low-Pt-loading counter electrodes for dye-sensitized solar cells based on chemical bath deposited microstructured nickel layer

Several hundred Ni microspheres with a diameter of 2–3 μm coated on frosted glass by chemical bath deposition are used as conductive substrates. Then, low-temperature immersion method (LTIM) and thermal decomposition method (TDM) are adopted respectively to deposit a thin Pt layer on Ni/glass and obtain Pt/Ni/glass electrodes which were employed as counter electrodes (CEs) for dye-sensitized solar cells (DSCs). The results show that the DSC device with well-optimized LTIM-electrode achieves a remarkable increase of 0.69 and 7.78% in fill factor (FF) and power conversion efficiency (PCE) respectively. However, well-optimized TDM-electrode and traditional sputtered-Pt-electrode demonstrate an efficiency of 6.59% and 7.55% with a FF of 0.65 and 0.69, respectively. In addition, the LTIM-electrode has the lowest Pt loading of only 15.4 μg/cm2 among these three types of CEs. Thus, LTIM presents here paved the way for the preparation of excellent electrocatalytic CEs with extremely low Pt loading on F-doped SnO2 (FTO) free of Ni/glass substrates in DSCs, greatly reducing the cost of present photovoltaic devices. Furthermore, this LTIM can be applied to deposit other noble metals on a variety of flexible substrates, including polyethylene naphthalate or terephthalate.

One-step direct fabrication of manganese oxide electrodes by low-temperature thermal decomposition of manganese formate-amine ink for supercapacitors

A one-step direct fabrication of thin-film manganese oxide electrodes was accomplished via low-temperature thermal decomposition of inks composed of manganese formate (Mnf), alkylamines, and hexanol. As complexing agents, amines were used in molar ratios of Mnf:amine that ranged from 1:1 to 1:4. Prepared inks were directly coated onto the substrate, and then calcined at 170–210 °C under air. Cyclic voltammetry and charge/discharge measurements of the thin films were conducted in an electrolyte solution. Following immersion, the specific capacitance of the electrodes increased and eventually reached a constant value. Based on the results of cyclic voltammetry (CV) at 1 mV s−1, a thin-film electrode fabricated at 180 °C from Mnf-octylamine-hexanol ink at a molar ratio of 1:3:0.5 had the highest level of specific capacitance at 400 F g−1. CV measurement at 1000 cycles revealed a deterioration of specific capacitance of only 5%, which indicates good stability for this thin-film electrode.

Preparation of Ni2P Supported on Al2O3 and B2O3 Mixed Oxides by Temperature-Programmed Reduction of Phosphate Precursors with Low P/Ni Ratios

Two types of mixed oxides of B2O3 and Al2O3 were prepared. Aluminum borates (ABx, x represents the B/(B + Al) ratio) were prepared by low-temperature thermal decomposition of aluminum nitrate and H3BO3 sustained by the simultaneous oxidation of an organic agent (glycerol), while B2O3-Al2O3 with B/(B + Al) ratio of 0.3 was obtained by incipient wetness impregnation of H3BO3 on a commercial γ-Al2O3 support. Tetrahedrally, pentahedrally, and octahedrally coordinated Al3+ cations were all present in AB0.3 with ratios of 10.9/21.3/67.8, while no pentahedrally coordinated Al3+ was observed in B2O3-Al2O3. B2O3 was enriched in the surface of AB0.3. The Ni2P phase was obtained by temperature-programmed reduction of a phosphate precursor with a P/Ni ratio as low as 1.2 supported over both AB0.3 (Ni-P(1.2)/AB0.3) and B2O3-Al2O3 (Ni-P(1.2)/B2O3-Al2O3). This suggests that the surface B2O3 inhibits the reaction between nickel phosphates and Al2O3, and thus facilitates the formation of Ni2P. The hydrodesulfurization (HDS) of dibenzothiophene (DBT) over the supported Ni2P catalysts occurred mainly by the direct desulfurization pathway, and Ni-P(1.2)/B2O3-Al2O3 was much more active than Ni-P(1.2)/AB0.3. These features make B2O3-Al2O3 a promising support for Ni2P catalysts. The HDS of DBT followed a pseudo-first-order kinetics over Ni-P(1.2)/B2O3-Al2O3, whereas over Ni-P(1.2)/AB0.3 it can be described by pseudo-zero-order kinetics. The pseudo-zero-order kinetics suggests a strong adsorption of DBT on Ni-P(1.2)/AB0.3, which could be responsible for its lower activity.

Sustainable Process for the Depolymerization/Oxidation of Softwood and Hardwood Kraft Lignins Using Hydrogen Peroxide under Ambient Conditions.

The present study demonstrated a sustainable and cost-effective approach to depolymerize/oxidize softwood (SW) and hardwood (HW) kraft lignins using concentrated hydrogen peroxide at temperatures ranging from 25 to 35 °C, in the absence of catalysts or organic solvents. The degree of lignin depolymerization could be simply controlled by reaction time, and no further separation process was needed at the completion of the treatment. The obtained depolymerized lignin products were comprehensively characterized by GPC–UV, FTIR, 31P-NMR, TGA, Py-GC/MS and elemental analysis. The weight-average molecular weights (Mw) of the depolymerized lignins obtained from SW or HW lignin at a lignin/H2O2 mass ratio of 1:1 after treatment for 120 h at room temperature (≈25 °C) were approximately 1420 Da. The contents of carboxylic acid groups in the obtained depolymerized lignins were found to significantly increase compared with those of the untreated raw lignins. Moreover, the depolymerized lignin products had lower thermal decomposition temperatures than those of the raw lignins, as expected, owing to the greatly reduced Mw. These findings represent a novel solution to lignin depolymerization for the production of chemicals that can be utilized as a bio-substitute for petroleum-based polyols in polyurethane production.

Effects of Nano Particles of Ruthenium Oxide-Based Hybrid Catalyst on Sensitivity to Hydrogen Phosphate Ions

Hydrogen phosphate (HPO4 2-, HPO) is one of the target ions to detect and quantify phosphorus in environmental water, and the quantification is normally carried out by molybdenum blue method, in which a sample containing phosphate is mixed with an acid solution of Mo (VI) and the absorbance of the resulted PMo12O40 3− is measured. Our group has recently found a novel catalyst to oxidize HPO, of which the oxidation current measured with RDE at 60 s after applying the oxidation potential is linear to the HPO concentration, suggesting a possibility of the quantification of HPO in environmental water by the electrochemical sensor [1, 2]. The catalyst is the mixture of ruthenium oxide and tantalum oxide obtained by thermal decomposition method. Since the oxides are immiscible, the obtained catalyst is the hybrid system consisting of nano ruthenium oxide particles dispersed in amorphous tantalum oxide matrix. In this paper, the hybrid catalysts were prepared at different metal ratios and thermal decomposition temperatures to change the size and distribution of ruthenium oxide nano particles and the sensing properties of those catalysts to HPO were examined.The precursor solution containing RuCl3 with and without TaCl5 in n-butanol was painted on the titanium disk (4 mm in diameter, 10 mm in thickness), which had been degreased and etched in 10 wt% oxalic acid solutions at 90 oC for 1 h, and then heated at a temperature ranging from 260 oC to 500 oC for 20 min. This process was repeated several times to obtain RuO2-Ta2O5 or RuO2 coated titanium disk. The Ru:Ta ratio was 30:70 mol% to 80:20 mol%. Characterization of the oxide coating was carried out by XRD, SEM, and EDX. The coated disk was mounted in RDE equipment and was used as the working electrode with the platinum counter electrode and the KCl saturated Ag/AgCl reference electrode. The electrolytes were based on 50 mmol/L KCl solutions, and Na2HPO4 was added into the solution. Cyclic voltammetry (CV) and chronoamperometry (CA) were performed, and the current transient in CA was measured at 1200 rpm. All measurements were carried out at 30 oC.The XRD results of the RuO2-Ta2O5 coatings showed clear diffraction peaks of RuO2 when the coatings were prepared at 500 oC, and the peaks were weakened or disappeared when the thermal decomposition temperature was 260 oC. SEM observation of the coating surface also indicated that the diffraction peaks were seen with RuO2 particles of 100 nm or more, while the flat surface containing nano RuO2 particles dispersed in amorphous Ta2O5 matrix was observed for the coating prepared at 260 oC. The Ru:Ta ratio also influenced on the surface morphology; a higher tantalum ratio makes RuO2 smaller which means that Ta2O5 suppresses the crystal growth of RuO2 even at 500 oC. The oxidation current was measured by chronoamperometry, and the data at 60 s obtained with different concentrations of HPO4 2- were plotted, giving a linear relationship between the concentration and the oxidation current for a maximum concentration range from 10-6 mol/L to 10-2 mol/L. The slope of the plots was defined as the sensitivity to HPO and the results on the sensitivity at different thermal decomposition temperatures and different metal ratios revealed that a lower thermal decomposition temperature made a higher sensitivity and the sensitivity was maximum at the Ru ratio of 50 mol%. Low temperature thermal decomposition like at 260 oC produces nano RuO2 particles, while RuO2 is grown large with increasing temperature, so that the active surface area to HPO is high at low thermal decomposition temperature, resulting in a high sensitivity. The increase in the Ru ratio seems to make the sensitivity higher, since RuO2 is active to and Ta2O5 has no activity to HPO. However, the increase in the Ru ratio also means the decrease in Ta2O5 which has a role to suppress the growth of RuO2 as the matrix of the hybrid catalyst, so that the sensitivity may be a maximum at around Ru = 50 mol%. We will also show the effects of RuO2 particle size on the sensitivity which are obtained from the results with RuO2 coatings on titanium disk prepared at different thermal decomposition temperatures.This work was supported by JSPS KAKENHI Grant Number JP19175698.Reference[1] M. Morimitsu, T. Tsukuma, Y. Shigeta, K. Kawaguchi, WET2019, Abst#3A-08, Osaka (2019).[2] M. Morimitsu, C. Iketani, T. Tsukuma, K. Kawaguchi, ACCS2019, Abst#BO-006, Bali (2019).

Beech wood modification based on in situ esterification with sorbitol and citric acid

In this study, modification of European beech wood (Fagus sylvatica) through in situ esterification of sorbitol and citric acid (SorCA) was investigated at two curing temperatures, 140 and 160 °C. In order to determine the optimum condition for modification, an aqueous solution of SorCA at varying concentrations was evaluated (10, 20, 30, and 55% w/w). Physical, mechanical, chemical, and durability properties of the modified wood were examined. Results have disclosed that among different SorCA concentrations, treatment with SorCA at 30% w/w was considered as the optimum concentration independent of the curing temperature. Under these conditions, anti-swelling efficiency increased to approx. 55% and modulus of elasticity increased slightly with approx. 9% in comparison with untreated wood. Decay resistance against white-rot (Trametes versicolor), brown-rot (Coniphora puteana), and soft-rotting microfungi classified the SorCA-30%-modified wood as very durable. In addition, thermogravimetric study evidenced that SorCA 30%-modified wood has a lower thermal decomposition temperature in comparison with untreated wood/wood control by 20 °C difference, indicating that the SorCA-modified wood possibly has fire-retardant properties. However, due to the acidic properties of the SorCA solution, modulus of rupture (MOR) and mainly work to maximum load in bending decreased considerably.

Template-free Synthesis of Mesoporous and Crystalline Transition Metal Oxide Nanoplates with Abundant Surface Defects

Summary Mesoporous transition metal oxides with crystalline walls show promising applications in catalysis and energy storage. Syntheses of those crystalline mesoporous oxides, however, currently remain as an unmet challenge because of the large volume shrinkage during crystallization in a sol-gel process. Here, we demonstrate a facile and general template-free method to prepare six mesoporous transition metal oxides, e.g., CuO, CoO, and spinel MCo2O4 (M = Co, Cu, Mn, Zn), with highly crystalline walls and continuous mesopores in the forms of two-dimensional nanoplates or nanosheets. The method is based on the thermal crystalline transformation from basic carbonates to mesoporous metal oxides. The crystal interconversion not only endows the crystallinity and mesoporosity of oxides but also generates abundant surface-step defects that show remarkable enhancement of the catalytic activity of porous oxides. Our method likely provides an alternative paradigm for cost-effective and universal synthesis of crystalline mesoporous oxides beyond the traditional templating methods.

Ablation induced by intense pulsed ion beam and its effects on energy deposition on solid target

Ablation effects play an important role in material processing with intense pulsed ion beam (IPIB) and IPIB diagnostics such as calorimeters and infrared detection may also be influenced by ablation. In this study, with numerical analysis and thermal imaging method, the ablation plume and its effects on energy deposition of IPIB on solid target was studied. Radiation experiments of polyvinyl chloride (PVC) targets with a thickness of 200 μm were carried out on BIPPAB-450 pulsed ion beam accelerator and the energy deposition of the ion beam was investigated with infrared imaging diagnostics. It is revealed that due to the low thermal conductivity and decomposition temperature of PVC, ablation plume can be formed during the early stage of beam irradiation and the ablation product may shield the energy of the ion beam from depositing in the target when energy density reaches a certain threshold. This effect needs to be taken into consideration in order to avoid its influence on applications and beam diagnostics.

Effect of aqueous and ethanolic extracts from pinhão coats on the properties of corn and pinhão starches

The Araucaria angustifolia seed, named pinhao, has a high content of carbohydrates, and it is considered an unconventional starch source. Its coats are rich in phenolic compounds, which can be easily extracted with some solvents. This study presents a method of aqueous and ethanolic extraction of phenolic compounds from pinhao coats and its incorporation into corn and pinhao starches. Thermogravimetry, differential scanning calorimetry, X-ray powder diffractometry, Fourier-transform infrared spectroscopy and field emission gun-scanning electron microscopy were applied to evaluate the thermal, structural and morphological properties of starches. The control samples were prepared under the same conditions, with deionised water and ethanol/water 55:45 v/v, without extracts. Starches incorporated with both extracts showed lower thermal decomposition temperatures than the native ones. The gelatinization enthalpy (ΔHgel) of corn starch decreased after incorporation with extracts. The ΔHgel of native pinhao starch was 7.3 J g−1. A higher ΔHgel was observed after treatment with ethanolic extract, while the aqueous extract caused a decrease in this value. Treatments did not change the diffraction patterns but change the relative crystallinity (RC) of starches, except to the samples treated with ethanol/water 55:45 v/v that maintained RC similar to the native ones. There was a good correlation of FTIR data with RC and ΔHgel. After incorporation with ethanolic extract, the pinhao starch showed superficial peeling. No change was observed in morphological characteristics for the other samples. Results indicate that there is an interaction between the phenolic compounds of the pinhao coats and the starch.

Influence of troilite on the decomposition of ammonium jarosite and estimated activation energy

Jarosite method is most widely employed to remove iron through the zinc hydrometallurgical process, and ammonium jarosite sediment is produced. The low-temperature thermal decomposition of the ammonium jarosite sediment is desirable to recover natural resources and protect the environment. Herein, we aimed to study the influence of troilite addition on thermal decomposition of hydrothermally synthesized ammonium jarosite. The ammonium jarosite gets decomposed at 300 °C and results in a hematite crystal phase. The hematite, pyrite and magnetite phases have been observed at 400 °C. Furthermore, the hematite and magnetite are present as major phases and pyrrhotite phase has been detected as the minor phase at 500 °C. In addition, the amount of magnetite and hematite exhibited linear and inverse relationships with heat treatment temperature, respectively, in the temperature range of 500–800 °C. Also, the sulfur has been completely decomposed during the jarosite process after roasting at 500 °C and the estimated activation energy value (Ea) of 503.4 kJ mol−1 has been obtained from $$\ln (v/T_{\text{p}}^{2} )$$ versus 1/Tp plots. Troilite can improve sulfur elimination from ammonium jarosite at low temperature.

Effect of microstructure on short pulse duration shock initiation of TATB and initial response mechanism

Micro-TATB particles with different sizes and 3D nanoporous TATB architectures with different specific surface areas were prepared through recrystallization to study short pulse duration shock initiation properties by electric gun technology. For micro-TATB, the initiation threshold significantly decreases with TATB average size ranging from 79.7 μm to 0.5 μm. For 3D nanoporous TATB architecture, the initiation threshold decreases and then increases with specific surface areas increased from 9.6 m2/g to 36.2 m2/g. The lowest initiation thresholds are obtained for the micro-TATB with average sizes of 1.3 μm and 0.5 μm, and 3D nanoporous TATB architecture with specific surface area of 22.4 m2/g. The shock initiation thresholds of micro-TATB and 3D nanoporous TATB architectures show significantly decreases with the porosity increased. The decomposition reaction and thermal conductivity properties were further investigated to understand the initial response mechanism. High porosity provides more collapse sites to generate high temperature for formation of hot spots. The low thermal conductivity and decomposition temperature could enhance the formation and ignition of the hot spots, and initial decomposition reaction of TATB. The effect of the decomposition temperature is higher than that of the thermal conductivity on the shock initiation properties. The enhanced decomposition reaction could promote energy release and transfer process from the ignition to the combustion. This work offers a new insight to understand the effects of microstructure on the shock initiation properties and the initial response mechanism of TATB.

High-Magnetization Tetragonal Ferrite-Based Films Induced by Carbon and Oxygen Vacancy Pairs.

Herein, a low-temperature thermal decomposition method is utilized to grow new stable tetragonal Fe3O4-based thick ferrite films. The tetragonal Fe3O4-based film possesses high saturation magnetization of ∼800 emu/cm3. Doping with approximately 10% Co results in a high-energy product of ∼10.9 MGOe with perpendicular magnetocrystalline anisotropy, whereas doping with Ni increases electrical resistivity by a factor of 6 and retains excellent soft magnetic properties (high saturation magnetization and low coercivity). A combined experimental and first-principles study reveals that carbon interstitials (CiB) and oxygen vacancies (VO) form CiB-VO pairs which stabilize the tetragonal phase and enhance saturation magnetization. The magnetization enhancement is further attributed to local ferromagnetic coupling between FeA and FeB induced by CiB-VO pairs in a tetragonal spinel ferrite lattice.

Experimental and Theoretical Study of Coating Spalling under High-Cycle Fractional Loading

An experimental and theoretical study of contact fatigue damage accumulation at the coating-substrate interface has been carried out for the case of frictional contact between a smooth coating and a rough counterbody. Coatings were synthesized via low-temperature thermal decomposition of metal (Al, Zr) carboxylate solutions, which resulted in the formation of nanoscale amorphous nanocrystalline oxide layers 20–400 nm thick (depending on the concentration of the film-forming solution and the number of loading cycles) on the substrate surface (quartz glass). The investigation included coating deposition, determination of coating mechanical properties by indentation, development of the friction test procedure, stress calculation at the coating-substrate interface by modeling high-cyclic frictional loading, and the choice of a damage accumulation model for the coating-substrate interface that relates the stress state to the number of cycles to coating spalling. Preliminary tests revealed the coating compositions and coating deposition techniques that provide the highest spalling resistance under cyclic contact loading. Parameters in the relation for contact fatigue damage accumulation were determined and the model was verified by analyzing the experimental load dependence of the number of cycles to coating spalling on the microscale. It has been shown that the linear damage summation model conventionally used for describing failure due to fatigue damage accumulation in some materials can be applied to investigate the coating-substrate interface whose properties depend not only on the properties of the interfacing materials but also on the coating deposition technique.

A new method for an efficient porous carbon/Fe3O4 composite based electromagnetic wave absorber derived from a specially designed polyimide

A new strategy was developed for the fabrication of the honeycomb-like porous carbon (HPC) material, involving a liquid-liquid phase separation process and a pyrolysis process. First of all, a novel polyimide containing benzothiazole moieties was designed and synthesized as the carbon precursor. Due to the high glass-transition temperature (Tg, 404 °C) and the low initial thermal decomposition temperature (394 °C) of this specially designed polyimide, the pore structure formed during the phase separation process was well maintained in the following pyrolysis process. As determined by SEM, the product has a honeycomb-like pore structure with a high uniformity. XRD and Raman spectra manifested the resulting carbon material possessed a disordered graphite structure, which can greatly contribute to its EM wave dissipation ability. After modifying HPC with Fe3O4 nanoparticles, the nanocomposites (HPC/Fe3O4) achieved an excellent EM wave absorption performance. At the absorber thickness of 5.5 mm, a minimum reflection loss (RL) value of −20.1 dB was achieved. Moreover, with the variation of the absorber thickness from 1.3 to 5.0 mm, the minimum RL curves in Ku band were all lower than −10 dB. These results demonstrated the polyimide could be an excellent precursor for the synthesis of porous carbon materials with controllable morphology. Additionally, HPC/Fe3O4 could be a promising material for applications in the field of EM wave absorption.

Low-temperature thermal decomposition of heavy petroleum distillates: interconnection between the electrical properties and concentration of paramagnetic centres

Changes of paramagnetic centers (PC) concentration in petroleum dispersed systems (PDS) are studied in the process of low-temperature thermolysis. Complex investigation of physicochemical, rheological and electrophysical properties of high-boiling oil fractions is performed. Based on the analysis of the experimental results it can be concluded that the PDS under investigation can be regarded as amorphous broadband organic semiconductors for which PC plays a role of dopant. It shows the perspectives of the asphaltenes usage as a basis for the photovoltaic devices.

Fabrication of porous β-Bi2O3 nanoplates by phase transformation of bismuth precursor via low-temperature thermal decomposition process and their enhanced photocatalytic activity

Direct phase transformation of bismuth complex nanoplates to β-Bi2O3 ones was induced by low-temperature annealing at 250 °C. The β-Bi2O3 nanoplates showed a nanoporous structure, which retained the tetragonal framework of the original bismuth complex nanoplates while releasing gas molecules produced during thermal decomposition, thereby enabling the formation of nanoporous structures extending through the nanoplate surfaces. The sizes, structures, optical properties, and composition distributions of the synthesized bismuth-organic complex and porous β-Bi2O3 nanoplates were characterized by scanning electron microscopy, energy-dispersive x-ray spectroscopy, infrared spectroscopy, UV–vis diffuse reflectance spectroscopy, and x-ray diffraction. The porous β-Bi2O3 nanoplates prepared by low-temperature annealing at 250 °C for 3, 5, and 7 h showed photocatalytic activities for the photodegradation of methylene blue. The porous β-Bi2O3 nanoplates annealed for 7 h showed the best photocatalytic activity. To confirm the nanoplate photocatalyst cytotoxicity, cell viability tests were performed by treating HEK293 normal kidney cells with the porous β-Bi2O3 nanoplates.

Synthesis and nonlinear optical properties of novel conjugated small molecules based on indole donor

Buchwald-Hartwig amination of aryl halides with solvent-free condition was used for the preparation of electron donors with high density of electron cloud. Organic second order nonlinear optical chromophore ZML-c based on this electron donor was designed and synthesized. And chromophore ZML-ref without modified groups was also prepared as the contrast. Their delocalized energy levels were estimated by UV–Vis. spectra. Their thermal properties were studied by thermogravimetric analysis (TGA). Obviously, chromophore ZML-c showed lower delocalized energy levels and lower thermal decomposition temperature (just about 160 °C). The poled films showed the largest electro-optic (EO) coefficients of 23.5 pm/V and 10.6 pm/V respectively for chromophore ZML-c and ZML-ref. These results indicate that effective modification in indole ring may be a promising way to drastically change the electro-optical features of the titled compounds and show a direction of designing new electron donor in the field of nonlinear optical materials.