浸渍法制备硅钨酸修饰的炭载钯催化剂电催化甲酸氧化

用浸渍的方法制备了硅钨酸（SiWA）修饰的炭载Pd(Pd/C-SiWA)催化剂。 计时电流曲线研究表明,在Pd/C和Pd/C-SiWA催化剂电极上,3000 s时的电流密度分别为0.013和0.082 A/mg,分别为10 s时电流密度的2.5%和14.1%。 结果表明,Pd/C-SiWA催化剂对甲酸氧化的电催化稳定性要远远优于Pd/C催化剂。 这是因为Pd/C催化剂上SiWA的修饰抑制了甲酸的自分解, 从而减小了CO的毒化作用,改进了Pd/C催化剂对甲酸氧化的电催化和稳定性。     

磷钼酸（PMA）修饰炭载Pd催化剂对甲酸氧化的电催化性能

为了提高直接甲酸燃料电池（DFAFC）中炭载Pd（Pd/C）催化剂对甲酸氧化的电催化性能,用回流法制备了磷钼酸（PMA）修饰的炭载Pd（PMA-Pd/C）催化剂.并用谱学技术和电化学技术表征了催化剂的组分和结构,发现PMA通过化学作用而牢固地固定在Pd表面.由于PMA-Pd/C催化剂能抑制甲酸的自分解,因此,PMA-Pd/C催化剂对甲酸氧化的电催化性能优于Pd/C催化剂.     

碳纳米管载Pd-Au催化剂的合成及其对甲酸氧化的电催化性能

将萘-1-亚甲基膦酸通过π-π堆积作用修饰在多壁碳纳米管(MWCNT)上,然后制备了MWCNT载Pd(Pd/MWCNT)催化剂。 利用Pd和HAuCl4间的置换反应制得MWCNT载Pd-Au(Pd-Au/MWCNT)催化剂。 透射电子显微镜(TEM)、X射线光电子能谱(XPS)和X射线衍射光谱(XRD)测试结果显示,非合金化的Pd-Au纳米粒子均匀分布在MWCNT表面。 循环伏安和计时电流测试显示,非合金化Pd-Au/MWCNT催化剂对甲酸氧化的电催化活性以及稳定性优于Pd/MWCNT催化剂。     

Reactions with Addition Compounds Containing Activated Formic Acid

Addition compounds of formic acid with tertiary organic bases in ratios higher than that required for salt formation (3:1 and 2:1 adducts) contain formic acid in a highly activated form. In particular, the 3:1 adducts of formic acid with trimethylamine and triethylamine are liquid reducing agents that are convenient to handle and are suitable for use in many selective reductions. These addition compounds have a surprisingly strong reducing action on sulfur dioxide, which is rapidly converted, even at low concentrations, into crystalline rhombic sulfur. Sulfones and polysulfones can be prepared in good yields by three-component reactions from activated formic acid, sulfur dioxide, and polarized vinyl compounds.     

改进液相还原法制备的Pd/C催化剂对甲酸氧化的电能

用液相还原法制备炭载Pd(Pd/C)催化剂时,先用Na₂CO₃调节溶液pH值至8～9,然后加入还原剂还原PdCl₂,由于PdCl₂能与Na₂CO₃形成配合物,降低了得到的Pd粒子聚集倾向,使制得的Pd/C催化剂中Pd粒子的平均粒径和相对结晶度都较小,分别为3.57 nm和1.37。而没有加Na₂CO₃制得的Pd/C催化剂中Pd粒子的     

Facile Synthesis of Carbon‐Supported Ultrasmall Ag@Pd Core‐Shell Nanocrystals with Superior Electrocatalytic Activity for Direct Formic Acid Fuel Cell Application

To design electrocatalysts with excellent performance, morphology, composition and structure is a decisive influential factor. In this work, ultrasmall Ag@Pd core‐shell nanocrystals supported on Vulcan XC72R carbon with different Ag/Pd atomic ratios are synthesized via a facile successive reduction approach with formaldehyde and ethylene glycol as reducing agents, respectively. The Ag‐core/Pd‐shell nanostructures are revealed by high‐resolution transmission electron microscopy (HRTEM). Ag@Pd core‐shell nanocrystals possess a narrow size distribution with an average size of ca. 4.3 nm. In comparison to monometallic Pd/C and commercial Pd black catalysts, such Ag@Pd core‐shell nanocrystals display excellent electrocatalytic activities for formic acid oxidation, which may be due to high Pd utilization derived from the formation of Ag@Pd core‐shell nanostructure and the strong interaction between Ag and Pd.     

电解液对炭载Pd催化剂对甲酸氧化的电催化性能的影响

为了了解(NH4)2SO4,K2SO4和H2SO4电解液对炭载Pd(Pd/C)催化剂对甲酸氧化的电催化性能的影响和机理,用电化学方法测量了Pd/C催化剂在不同电解液中对甲酸氧化的电催化性能。发现在不同电解液中,Pd/C催化剂对甲酸氧化的电催化活性和稳定性按(NH4)2SO4>K2SO4>H2SO4的次序降低。由于在含甲酸的电解液中,不同电解液的pH值差别较小,电解液的pH值只有较小的影响。其次,电解液的电导率对甲酸氧化峰峰电位有一定的影响。最后,由于NH4+起着特殊作用,它能降低CO在Pd/C催化剂电极上的吸附量,因此,在(NH4)2SO4电解液中,Pd/C催化剂对甲酸氧化的电催化性能最好。     

The cis–trans transformation of cyclohexane formic acid ester compounds

Trans-alkyl cyclohexane formic acid phenol ester compounds are synthesised by reaction of trans-cyclohexane formic acid and phenols. This process also produces many harmful cis-alkyl cyclohexane formic acid phenol ester compounds that are harmful to the environment. Using p-toluenesulphonic acid as the catalyst in this experiment, these cis compounds were transformed to their trans form. The yields of trans-alkyl cyclohexane formic acid phenol ester compounds were more than 70%, which was significantly higher when compared to the yields of 40–60% obtained using the control method. The effects of catalyst, reaction time and reaction temperature on cis–trans transformation were investigated. The possible mechanism of cis–trans transformation has been discussed in this report.     

过量甲酸水溶液氧化环戊烯制备戊二醛

过氧化氢;过量甲酸水溶液氧化环戊烯制备戊二醛     

Hydrogen from Formic Acid through Its Selective Disproportionation over Sodium Germanate—A Non‐Transition‐Metal Catalysis System

A robust catalyst for the selective dehydrogenation of formic acid to liberate hydrogen gas has been designed computationally, and also successfully demonstrated experimentally. This is the first such catalyst not based on transition metals, and it exhibits very encouraging performance. It represents an important step towards the use of renewable formic acid as a hydrogen‐storage and transport vector in fuel and energy applications.     

Tunable Periodically Ordered Mesoporosity in Palladium Membranes Enables Exceptional Enhancement of Intrinsic Electrocatalytic Activity for Formic Acid Oxidation

Developing superior electrocatalysts for formic acid oxidation (FAO) is the most crucial step in commercializing direct formic acid fuel cells. Herein, we electrodeposited palladium membranes with periodically ordered mesoporosity obtained by asymmetrically replicating the bicontinuous cubic phase structure of a lyotropic liquid‐crystal template. The Pd membrane with the largest periodicity and highest degree of order delivered up to 90.5 m² g^?1 of electrochemical active surface area and 3.34 A mg^?1 electrocatalysis capability towards FAO, 3.8 and 7.8 times the values of the commercial Pd/C catalyst, respectively. By controlling the temperature and potential of the electrodeposition procedure, the periodicity area and order degree of the mesoporosity are highly tunable. These Pd membranes gave prototype formic acid fueled cells with 4.3 and 2.4 times the maximum current and power density of the commercial Pd/C catalyst.     

有机溶胶法制备直接甲酸燃料电池用Pd/C阳极催化剂

采用改进的有机溶胶法制备了用于直接甲酸燃料电池(DFAFC)中甲酸氧化的炭载Pd(Pd/C)催化剂。制备Pd/C催化剂时,以乙醇作溶剂,SnCl2作还原剂。控制溶剂的蒸发温度就能控制Pd/C催化剂中Pd粒子的平均粒径和相对结晶度。溶剂蒸发温度与Pd/C催化剂中Pd粒子的平均粒径和相对结晶度不成正比关系。在选择合适的溶剂蒸发温度时,能制得Pd粒子的平均粒径至6.5 nm和相对结晶度至2.85的Pd/C催化剂。比较了具有不同Pd粒子的平均粒径和相对结晶度的Pd/C催化剂对甲酸氧化的电催化性能。结果发现,Pd粒子的平均粒径小和相对结晶度低的Pd/C催化剂对甲酸氧化有好的电催化性能。     

偏钒酸钠对甲酸在Pd/C催化剂上氧化的电催化性能影响的机理

直接甲酸燃料电池的两大问题是Pd催化剂对甲酸氧化的电催化稳定性不好和Pd能催化甲酸分解。研究发现,当Pd/C在偏钒酸钠溶液中浸泡后能吸附上VO3-,吸附上VO3-的Pd/C催化剂对甲酸分解的催化性能会大大降低,由甲酸分解产生的CO的量也大大降低,使Pd/C催化剂被CO毒化的几率也大大降低,因此,在偏钒酸钠溶液中浸泡后的Pd/C催化剂对甲酸氧化的峰电流密度要比没有浸泡的Pd/C催化剂高13%左右。计时电流曲线的测量表明,6000 s时在偏钒酸钠溶液中浸泡后的Pd/C催化剂对甲酸氧化的峰电流密度要比没有浸泡的Pd/C催化剂高42%左右。结果证明,在偏钒酸钠溶液中浸泡能提高Pd/C催化剂对甲酸氧化的电催化活性,特别是电催化稳定性。     

炭载Pd-P催化剂对甲酸氧化的电催化性能

用黄磷作原料,制备了具有不同Pd-P原子比的碳载Pd-P(Pd-P/C)催化剂,并且使用X射线衍射(XRD)和能量色散X射线光谱仪(EDX)等手段对制备的催化剂进行了表征,总结了P含量对Pd-P合金纳米粒子的粒径和晶体结构的影响。电化学测试结果表明,甲酸在Pd/C、Pd₁P₆/C 和Pd₁P₈/C催化剂上,氧化峰峰电位由低到高依次为Pd₁P₆/C ﹤Pd₁P₈/C﹤Pd/C,电化学稳定性顺序为Pd₁P₆/C >Pd₁P₈/C>Pd/C,Pd₁P₆/C 催化剂对甲酸氧化的催化性能最佳,适量的P掺杂能够增强Pd/C催化剂对甲酸氧化的电催化活性和稳定性,因此,Pd-P/C催化剂是一类具有应用前景的直接甲酸燃料电池(DFAFC)阳极催化剂。     

Presence of β-Turn Structure in Recombinant Spider Silk Dissolved in Formic Acid Revealed with NMR

Spider dragline silk is a biopolymer with excellent mechanical properties. The development of recombinant spider silk protein (RSP)-based materials with these properties is desirable. Formic acid (FA) is a spinning solvent for regenerated Bombyx mori silk fiber with excellent mechanical properties. To use FA as a spinning solvent for RSP with the sequence of major ampullate spider silk protein from Araneus diadematus, we determined the conformation of RSP in FA using solution NMR to determine the role of FA as a spinning solvent. We assigned ¹H, ¹³C, and ¹⁵N chemical shifts to 32-residue repetitive sequences, including polyAla and Gly-rich regions of RSP. Chemical shift evaluation revealed that RSP is in mainly random coil conformation with partially type II β-turn structure in the Gly-Pro-Gly-X motifs of the Gly-rich region in FA, which was confirmed by the ¹⁵N NOE data. In addition, formylation at the Ser OH groups occurred in FA. Furthermore, we evaluated the conformation of the as-cast film of RSP dissolved in FA using solid-state NMR and found that β-sheet structure was predominantly formed.     

固载Ru基催化剂上二氧化碳加氢合成甲酸的研究(IV): 反应机理

探讨了在CO₂加H₂合成HCOOH过程中原位合成的固载Ru基催化剂的可能结构、CO₂的活化方式以及可能的反应机理. 在反应中, 固载Ru配合物中的一个P配体首先解离, 被质子型溶剂ROH取代而生成循环活性物质, 然后CO₂正插入Ru—H键生成甲酸酯配合物, 之后甲酸酯配合物中的Ru—O₂CH键被H₂氢解生成HCOOH, 而本身重新转化为活性物质, 完成催化循环.     

非水溶剂水热法制备CeO2纳米粉

本文以甲酸为反应介质,采用非水溶剂水热法制备了CeO2纳米粉,XRD分析结果表明产物为萤石结构的立方相CeO2,TEM分析结果表明产物颗粒呈球形,粒径分布范围很窄,IR和XRS分析结果表明产物中无水,甲酸,NO3^-吸附;同时采用光声光谱对CeO2纳米粉的量子尺寸效应进行了研究。     

直接甲酸燃料电池炭载Pd阳极催化剂的稳定性

用X射线衍射和电化学方法研究了在甲酸溶液中浸泡一段时间后的Pd/C催化剂的结构和电催化性能, 发现在甲酸溶液中浸泡15 d后, Pd/C催化剂中Pd粒子的相对结晶度由1.73增加到3.34, 平均粒径由4.4 nm降低到1.8 nm, 对甲酸氧化的电催化活性和稳定性降低, 甲酸氧化的峰电流密度由9.3 mA/cm2降低到6.7 mA/cm2. 这可能是由Pd/C催化剂中的Pd在甲酸中会有一定的溶解和Pd/C催化剂能催化分解甲酸引起的.     

中空介孔碳化钨微球载钯催化剂对甲酸电催化性能

采用喷雾干燥法和还原炭化处理制备具有中空介孔结构的碳化钨钴复合粉(HTCCS),其中,钴的质量含量为6%。在碳化钨钴复合粉表面的钴和氯化钯发生置换反应,得到纳米Pd/WC复合催化剂。采用X射线粉末衍射(XRD)、扫描电镜(SEM)和透射电镜(TEM)对样品的形貌和晶型结构进行了表征。结果表明, 5.0-6.0nm钯纳米粒子取代钴均匀分布在碳化钨微球表面。采用循环伏安和计时电流法研究了在酸性溶液中Pd/WC催化剂对甲酸的电催化氧化性能,结果表明,Pd/WC催化剂比Pd/C催化剂对甲酸呈现出更高的电催化氧化活性和稳定性。