An EC-FTIR study on the catalytic role of Pt in carbon corrosion

In this study, we investigate the role of Pt in the corrosion of carbon by Fourier-transformed infrared spectroscopy coupled in situ with electrochemical measurements. We confirm that the carbon corrosion rate is strongly enhanced in the presence of Pt and shed light on the reaction mechanisms at both anode and cathode potentials. It is shown that carbon surface oxide species (phenol, ether, carboxylic and carbonyl groups), formed at low electrode potential E < 0.60 V vs. RHE, spillover back from the carbon support to the Pt nanoparticles, where they are converted into CO and then slowly oxidized into CO₂. At higher electrode potential E > 0.60 V vs. RHE, oxygenated species resulting from water splitting on Pt facilitate the removal of these carbon surface oxides species yielding increased kinetics for carbon corrosion.     

Adsorbate-substrate interaction between chlorodifluoromethane and titanium dioxide: Infrared spectroscopy and density functional theory studies

Infrared spectra of chlorodifluoromethane (CHClF₂) adsorbed on titanium dioxide (TiO₂) at room temperature have been investigated for the first time. From the comparison between the adsorption characteristics and the gas-phase spectra it can be deduced that the molecule interacts with the surface Lewis acid site (Ti⁴⁺) mainly through the Cl atom even if also the adsorption with one F atom is also observed. Moreover, the spectra show the presence of H-bonds between the CH group and the surface Lewis basic site (OH⁻ or O²⁻). In order to obtain more information on the molecule orientation and the variation of the structural parameters, a DFT-B3LYP study has been carried out considering the anatase (1 0 1) surface and evaluating the adsorption energetics in terms of interaction, distortion and binding energies. The obtained geometries confirm that both the acid-base interactions through Cl or F atoms are possible and suggest the formation of one H-bond between the CH group of the molecule and the Lewis basic site of the surface. The calculated vibrational frequencies of the adsorbed molecule have been found to be in reasonable agreement with the experimental data.     

基于SEM与FTIR研究改性钢渣/橡胶复合材料的热氧老化机理

钢渣是冶金工业中产生的主要固体废弃物,其产量约为每年粗钢产量的15%~20%。由于技术的局限,导致我国钢渣利用率较低,仅为年钢渣产量的10%,同时加之管理制度的不健全,导致钢渣大量露天堆放,对土地资源、地下水源,以及空气质量形成严重影响。面对上述问题,以热闷渣、电炉渣和风淬渣研发改性钢渣微粉,并且将改性钢渣微粉与复合橡胶进行复合制备改性钢渣/橡胶复合材料。依据《硫化橡胶或热塑性橡胶热空气加速老化和耐热试验》（GB/T3512—2014）对改性钢渣/橡胶复合材料进行热氧老化处理,采用平衡溶胀法测定改性钢渣/橡胶复合材料的交联密度,扫描电子显微镜（SEM）、热重分析仪（TGA）和傅里叶转换红外光谱仪（FTIR）分别测试其微观形貌、失重率和结构组成,从微观层面阐述改性钢渣/橡胶复合材料的热氧老化机理。结果表明在热氧老化前期老化作用在改性钢渣/橡胶复合材料表面,其内部以交联键形成反应为主;在热氧老化中期老化作用已经作用改性钢渣/橡胶复合材料内部,造成交联键断裂反应速度高于交联键形成反应速度,形成大量断裂交联键;在热氧老化后期由于改性钢渣/橡胶复合材料内部已经存在大量断裂交联键,导致主链及交联键断裂速度降低,交联键形成反应占优势。改性钢渣微粉以热闷渣（SiO₂含量高）为原材料,有利于形成聚合物大分子链贯穿炭黑网络的结构,提高综合性能,尤其是物理机械性与滞后性;以电炉渣、风淬渣（Fe₂O₃含量高）制备改性钢渣微粉,有利于热传导性能的改善,不仅提高改性钢渣/橡胶复合材料的耐热性,而且提高其硬度与脆性。热氧老化过程中改性钢渣/橡胶复合材料内部在橡胶分子链α-H上发生了不同程度的氧化反应,并在橡胶分子链周围生成了羟基、羧基和醇类化合物,双键烯氢含量降低。     

Insights into ultrasound-promoted degradation of naphthenic acid compounds in oil sands process affected water. Part I: Accelerated H-abstraction and decarboxylation of aromatic and alicyclic compounds

Propelled by enormous increase in demand for fuel sources, Canadian oil sands are becoming increasingly important as a fuel source due to their abundance and upgrading capability. However, extraction of bitumen, a high acid crude (HAC) oil, requires 2–3 units of water per unit of oil resulting in naphthenic acid (NA)-rich oil sands process affected water (OSPW) collected in effluent ponds. This study illustrates the role of sonochemistry in the accelerated degradation through H-abstraction and subsequent decarboxylation of aromatic and alicyclic naphthenic acid model compounds. Benzoic acid and 3-methylcyclohexane carboxylic acid were selected as model NA compounds to investigate the mechanism of hydroxyl radical (OH^•) initiated carboxylic acid degradation in 378 KHz sonochemical reactor. Established FTIR methods with low resolution LCMS spectroscopy confirmation were applied to determine the extent of carboxylic acid degradation and identify the formation of products. FTIR monitoring showed a non-linear degradation of carboxylic acids with formation of many intermediates highlighting the shift from cyclic carboxylic acids to cyclic alcohols during BA degradation. Subsequent decrease in carboxylic acid groups signifies scission of cyclic structures before complete mineralization. This is confirmed with the LCMS identification of products such as: 3-hydroxybenzoic acid and phenol. This study postulated new breakdown pathways for degradation of benzoic acid with complete mineralization at a sonochemical reaction time (SRT) of 4 h. A radical quenching process was also inferred through the formation of conglomerates during sonochemical degradation of BA. Extension of the study to 3-methylcyclohexane carboxylic acid (3mCHA) shows similar non-linearity with an increase in carboxylic acid groups indicating H-abstraction followed by ring-opened compounds. However, due to the complex nature of 3mCHA’s ring-opened compounds, complete mineralization is not achieved. The putative role of sonochemistry is a promising and sustainable degradation method for mitigating NAs in OSPW, but sonication periods need to be considered carefully to ensure adequate mineralization of their constituents and combinatorial methods with other advanced oxidation methods may be needed to enhance industrial application.In Part II, an in silico screening approach using first principles is reported to identify the breakdown of the organic compounds and determine molecular rates of reaction to confirm the mechanistic origins of the compounds formed.     

热分析联用技术在高分子材料热性能研究中的应用

主要综述了热重-傅里叶变换红外(TG-FTIR)、裂解-色谱/质谱(Py-GC/MS)以及热重-质谱(TG-MS)三种常见的热分析联用技术的测试方法、原理,近几年这几种方法在高分子材料热性能研究中的应用进展和成果表明它们为材料的热分解过程和机理的探索提供了切实可行的研究方法,文章最后还展望了这些方法在热分析技术发展中的重要前景。     

蛋白质和变性蛋白质二级结构的FTIR分析进展

蛋白质结构的研究一直是人们研究的一个热点,蛋白质在发生变性后,二级结构会改变,从而导致生物活性丧失,这些与医药学及食品科学等领域密切相关。傅里叶变换红外光谱(FTIR)作为一种无损、快速的分析方法在蛋白质二级结构的研究中发挥重要的作用,本文就FTIR对于蛋白质二级结构的研究作一初步概述,主要介绍FTIR研究蛋白质结构的主要方法、红外光谱的谱学特点。     

Synthesis,spectroscopic characterization,and X-ray crystal structure of tris(trimethylsilyl)cyanurate

Tris(trimethylsilyl)cyanurate, C₁₂H₂₇N₃O₃Si₃ (1), has been synthesized and characterized by elemental analysis, IR, Raman, ¹³C and ²⁹Si NMR, and thermogravimetric methods. The molecular and crystal structure has been determined by single crystal X-ray diffraction. This compound crystallized in space group P6₃/m (176), Z = 2 with a = 11.017(2), b = 11.017(2), c = 9.676(3) Å; α = 90°, β = 90°, γ = 120°. The geometry of the molecule is compared with tris(trimethylsilyl)cyamelurate.     

Rapid quantitative analysis of fayalite and silica formed during decarburization of electrical steel

Subscales on surfaces are affected by the temperature and oxidation potential during decarburization annealing of electrical steel containing 3 wt% silicon. Knowledge of the structural and chemical properties of the surface oxide layer subscales permits the control of high‐temperature oxidation processes in the electrical steel. In the present work, the oxide layers were characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectrometry, and glow discharge optical emission spectrometry (GD‐OES). The main oxide compounds formed within the subscales during decarburization annealing of the electrical steel were fayalite (Fe₂SiO₄) and silica (SiO₂). The fayalite and silica contents were quantitatively determined by wet analysis via the galvanostatic electrolysis method, and these oxide content measurements were compared with the fayalite content determined by FTIR spectrometry and the silica determined by GD‐OES. The results determined by rapid methods and wet analysis showed good agreement. The present findings show that FTIR spectrometry and GD‐OES measurements may be used for the rapid quantitative analysis of fayalite and silica in surface oxide layers during the manufacture of electrical steel. Copyright © 2011 John Wiley & Sons, Ltd.     

Mass and bond density measurements for PECVD a-SiCx:H thin films using Fourier transform-infrared spectroscopy

The absolute concentration of chemical bonds in Plasma Enhanced Chemically Vapor Deposited (PECVD) a-SiC_x:H thin films have been determined via combining transmission Fourier-Transform Infra-red (FTIR) spectroscopy with X-ray Reflectivity (XRR) and Rutherford Backscattering (RBS) mass density and composition measurements. Specifically, we demonstrate in this paper that the integrated absorbance for the Si-C stretch in FTIR is linearly proportional to the mass density of PECVD a-SiC_x:H films as determined by XRR and RBS. This linear relationship allows us to accurately determine the IR absorption cross section for the Si-C stretch. Using these cross sections in combination with IR proportionality constants/cross sections published by other researchers, we demonstrate that mass densities in agreement with XRR and RBS can be calculated from the integrated absorbances of the Si-C, Si-H, and C-H stretches in FTIR spectra. From additional mass balance relationships, we further demonstrate that the full elemental and bond concentrations can be determined. This analysis reveals the presence of significant Si-Si and C-C bonding in the a-SiC_x:H films that was not clearly identified in previous FTIR investigations due to the low IR activity for these homopolar bonds. The bond and mass density calculations are demonstrated for both 3C-SiC and a-SiC_x:H thin films with mass density values ranging from 1 to 3.2 g/cm³.