A light-modulated chemosensor for methanol with ratiometry and colorimetry

A light-modulated chemosensor for methanol has been developed by using a photochromic spirophenanthoxazine as an indicator. In such a sensor, methanol can be detected easily by colorimetric recognition with high selectivity and anti-interference. Moreover, the concentration of indicator can be modulated and manipulated by light, which provides a simple way for the detection of methanol in a wide range of detectable limit that would be useful in different detection cases.     

Mordenite-incorporated PVA–PSSA membranes as electrolytes for DMFCs

Composite membranes with mordenite (MOR) incorporated in poly vinyl alcohol (PVA)–polystyrene sulfonic acid (PSSA) blend tailored with varying degree of sulfonation are reported. Such a membrane comprises a dispersed phase of mordenite and a continuous phase of the polymer that help tuning the flow of methanol and water across it. The membranes on prolonged testing in a direct methanol fuel cell (DMFC) exhibit mitigated methanol cross-over from anode to the cathode. The membranes have been tested for their sorption behaviour, ion-exchange capacity, electrochemical selectivity and mechanical strength as also characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis. Water release kinetics has been measured by magnetic resonance imaging (NMR imaging) and is found to be in agreement with the sorption data. Similarly, methanol release kinetics studied by volume-localized NMR spectroscopy (point resolved spectroscopy, PRESS) clearly demonstrates that the dispersion of mordenite in PVA–PSSA retards the methanol release kinetics considerably. A peak power-density of 74 mW/cm² is achieved for the DMFC using a PVA–PSSA membrane electrolyte with 50% degree of sulfonation and 10 wt.% dispersed mordenite phase. A methanol cross-over current as low as 7.5 mA/cm² with 2 M methanol feed at the DMFC anode is observed while using the optimized composite membrane as electrolyte in the DMFC, which is about 60% and 46% lower than Nafion-117 and PVA–PSSA membranes, respectively, when tested under identical conditions.     

CuCl2和HY分子筛的表面反应及Cu/Y分子筛的制备及其催化甲醇氧化羰基化

以CuCl₂为前驱物与HY分子筛进行固相离子交换制备了Cu/Y催化剂,采用热重方法研究了CuCl₂与HY分子筛的表面固相离子交换反应,结合活性测试表明催化剂中高度分散的CuCl和离子交换形式的Cu⁺物种是甲醇氧化羰基化合成碳酸二甲酯的催化活性中心。X射线光电子能谱表征和元素分析结果表明,活性金属Cu主要以CuCl形式存在于分子筛外表面,而在分子筛笼内则以交换的Cu⁺和少量吸附的CuCl形式存在。与以CuCl为交换铜源所制催化剂相比,以CuCl₂为铜源制备的催化剂Cu含量低,催化活性更高。     

具有优异甲醇催化氧化性能的Pt/MoO3-WO3/CNTs催化剂

以聚二烯丙基二甲基胺盐酸盐(PDDA)为连接剂,采用原位自组装方式将MoO3和WO3负载到碳纳米管(CNTs)上,然后通过乙二醇还原法负载Pt纳米颗粒,得到Pt纳米颗粒均匀分布的Pt/MoO3-WO3/CNTs催化剂.当氧化物总量控制在10 wt%,MoO3与WO3摩尔比为1:0.5时,Pt/MoO3-WO3/CNTs催化剂催化甲醇氧化活性最高,甲醇氧化峰电流If高达835 A/gPt.WO3和MoO3的加入提高了催化剂的甲醇氧化活性、抗CO中毒能力和稳定性,使得Pt/MoO3-WO3/CNTs催化剂表现出优异的甲醇电催化氧化性能.     

以方沸石负载Ni(Ⅱ)催化剂修饰的电极电氧化甲醇(英文)

There is a high overvoltage in the oxidation of methanol in fuel cells,and so modified electrodes are used to decrease it.A modified electrode that used Ni(II) loaded analcime zeolite to catalyze the electrooxidation of methanol in alkaline solution was proposed.Analcime zeolite was synthesized by hydrothermal synthesis,and Ni(II) ions were incorporated into the analcime structure,which was then mixed with carbon paste to prepare modified electrode.The electrocatalytic oxidation of methanol on the surface of the modified electrode in alkaline solution was investigated by cyclic voltammetry and chronoamperometry.The effects of the scan rate of the potential,concentration of methanol,and amount of zeolite were investigated.The rate constant for the catalytic reaction of methanol was 6 × 103 cm3 mol-1 s-1 from measurements using chronoamperometry.The proposed electrode significantly improved the electron transfer rate and decreased the overpotential for methanol oxidation.     

无表面活性剂Pt和PtRu纳米粒子制备及其甲醇氧化活性

利用一种简单的方法制备不含任何表面活性剂并具有高甲醇氧化活性的Pt和PtRu纳米电催化剂. 以CO为还原剂, CO和多壁碳纳米管(MWCNT_s)为保护剂和载体,通过一步反应得到沉积在多壁碳纳米管上Pt纳米粒子,在制备过程中无需使用任何有机溶剂或表面活性剂. 利用循环伏安法和计时电流法表征了所合成催化剂的甲醇氧化活性,甲醇氧化的峰电位(ca. 0.9 V vs. RHE)处的电流密度和比质量电流高达11.6 mA/cm² 和860 mA/mg_Pt. 在Pt/MWCNT_s表面电沉积Ru后,催化剂在低电位处的甲醇氧化活性得到提高,其在0.5和0.6 V的稳态比质量电流分别达到了20和80 mA/mg.     

利用原位红外光谱与微分电化学质谱联用技术研究在Pt以及PtRu电极上发生的甲醇氧化反应

利用电化学衰减全反射原位傅里叶变换红外光谱与微分电化学质谱联用技术,在流动电解池环境以及恒电位条件下研究了Pt电极和Pt电极通过表面电沉积Ru形成的PtRu电极(Pt_xRu_y)上发生的甲醇氧化反应(反应电解质溶液为0.1 mol/L HClO₄+0.5 mol/L MeOH). 在0.3～0.6 V(参比电极为可逆氢参比)实验用到的所有电极上,CO是唯一能从红外光谱观察到的与甲醇相关的表面吸附物;在Pt_0.56Ru_0.44电极上可以观察到CO吸附在Ru原子形成的岛上和CO线式吸附在Pt电极表面红外波段,而其他电极上只能观察到Pt表面上线式吸附的CO;甲醇氧化活性按Pt_0.73Ru_0.27>Pt_0.56Ru_0.44>Pt_0.83Ru_0.17>Pt的顺序递减;在0.5 V 时,甲醇在Pt_0.73Ru_0.27电极上的氧化反应的CO₂电流效率达到了50%.     

Preheated solvent exposure on P3HT:PCBM thin film: A facile strategy to enhance performance in bulk heterojunction photovoltaic cells

In this study, we explored the ability of a preheated solvent (methanol) to induce characteristic changes at the organic active layer/metal interface, thereby improving the performance of fabricated organic photovoltaic (OPV) cells composed of poly(3-hexylthiopene) (P3HT) and a [6,6]-phenyl-C₇₁-butyric acid methyl ester (PCBM) photoactive blend. Our results demonstrate that exposure to methanol (at room temperature, or preheated at 45 °C or 65 °C) improves the performance of the fabricated OPV cells. After preheated methanol exposure, the P3HT:PCBM thin films were tested for crystallinity, morphology, mobility, and photovoltaic characteristics. Our results revealed that use of the preheated solvent on the organic active layer significantly influences the micro/nano scale morphology and phase segregation of the P3HT:PCBM thin films, as well as the charge carrier mobility. It is hypothesized that the side chain ordering of P3HT and redistribution of PCBM could be results of the modified active layer. Consequently, OPV cells modified with the methanol preheated at 65 °C exhibited a power conversion efficiency (PCE) of 3.36%, with open-circuit voltage of 0.59 V, short-circuit current density of 13.83 mA/cm², and fill-factor of 0.41. In contrast, the unmodified P3HT:PCBM thin film (without methanol exposure) showed a PCE of only 2.13%.     

Electrocatalytic activity of ordered intermetallic PtSb for methanol electro-oxidation

Ordered intermetallic PtSb had been synthesized by arc-melted and then sintering treatment. The electro-oxidation of liquid methanol on PtSb was investigated at room temperature by cyclic voltammetry and chronoamperometry. The results are compared to those at a polycrystalline platinum electrode surface. It was found that PtSb intermetallic was catalytically more active than pure platinum according to the onset potential and current density. X-ray diffraction (XRD) and XPS technologies had been used to investigate the crystal structure and electron effect.     

Platinum particles dispersed poly(diphenylamine) modified electrode for methanol oxidation

A modified potentiostatic method, termed the ‘pulse pontentiostatic method’ (PPSM) was used to get nano fibrillar poly(diphenylamine) (PDPA) film on Indium tin oxide (ITO) coated glass electrode and also for making modified electrode with platinum particles dispersed in PDPA. Platinum clusters were electrodispersed under constant potential on PDPA films to obtain catalytic electrodes for methanol oxidation. Energy dispersive analysis of X-rays (EDAX) results showed that the Pt microparticles are deposited into PDPA film. Scanning electron micrograph, SEM images show that the deposition results spherical catalytic particles. X-ray photoelectron spectroscopy (XPS) results inform that the net electronic charge on carbon atom and also the imine/amine ratio was not affected by Pt loadings. The modification of electrode surface by nano fibular PDPA improves the electrocatalytic activity for methanol oxidation.