Study on the anodic reaction of Ni in an alkaline solution by transient pH detection based on scanning electrochemical microscopy (SECM)

The anodic reaction of Ni in an alkaline solution was studied by the tip–substrate voltammetry mode of scanning electrochemical microscopy (SECM) and cyclic voltammetry (CV). A platinum microdisc electrode was selected as the tip electrode, which functioned as a pH sensor with transient response capability. The pH value of the solution near the Ni electrode surface varied while the Ni substrate oxidation reaction occurred, and the pH variation could be detected by the tip faradic current. The cyclic voltammogram results showed that two types of hydroxides: i.e. α‐Ni(OH)₂ and β‐Ni(OH)₂ were formed during Ni oxidation in the lower potential region. In the proceedings of α‐Ni(OH)₂ → γ‐NiOOH and β‐Ni(OH)₂ → β‐NiOOH, the process of OH^? concentration decrease in the solution was ahead and behind of electron transfer in the solid phase, respectively. These results indicate that the OH^? adsorption process occurs as an elementary step in the former reaction and the H⁺ diffusion process from the inner to the outer layer of the solid phase occurs as a subsequent step in the latter reaction. The results also revealed that the oxide film on the Ni surface has a two‐layer structure. The real potential of the oxygen evolution reaction (OER) on the Ni surface with different cycles is also analyzed in the paper. Copyright © 2007 John Wiley & Sons, Ltd.     

The influence of the sacrificial anode nature on the mechanism of electrochemical arylation and alkylation of white phosphorus

The material of the sacrificial anode has a substantial effect on the nature and yield of the target products of electrochemical phosphorylation of organic halides by white phosphorus in the presence of the nickel complexes with 2,2"-bipyridine. The use of the zinc anode results in the products with tricoordinated phosphorus, viz., triorganylphosphines, the reaction on the aluminum anode affords triorganylphosphine oxides, and the presence of Mg²⁺ ions in the reaction mixture provides the transformation of white phosphorus into cyclic phosphines (PhP)₅.     

Swelling kinetics and release characteristic of crosslinked chitosan: Polyether polymer network (semi-IPN) hydrogels

The aqueous swelling kinetics of a series of crosslinked chitosan (cr-CS) with glutaraldehyde (GA) interpenetrating polyether hydrogels have been studied as functions of pH, the N-deacetylation degree of chitosan, the amount of crosslinking agent, the electrolyte composition in solution, temperature, and gel composition. Based on these results, the swelling mechanism of the hydrogels was discussed. The release profiles of chlorhexidini acetas from the semi-IPN were also investigated. © 1994 John Wiley & Sons, Inc.     

RESEARCH ON CATALYSTS OF ANTI-CARBON DEPOSITION FOR CH_4 REFORMING WITH CO_2

IntroductionMethaneandcarbondioxidearetWomaincompositionsforthegreenhouseeffectandtheworldglobewanningll].ItisbeneficialtoourlivingenviroIUnenttocontrolthereleaseofthesetwogases.Theconversionofmethanetothecommonfeedstocksynthesisgas(carbonmonoxideandhydro…     

5,15-二(对-取代苯基)八烷基卟啉及其金属配合物的合成

本文报道了五种5,15-二(对-取代苯基)-2,8,12,18-四乙基-3,7,13,17-四甲基卟啉(Ⅱa—Ⅱe)和五种5,15-二(对-取代苯基)-2,3,7,8,12,13,17,18-八甲基卟啉(Ⅰa—Ⅰe)以及它们的铜、铁、镍金属配合物的合成。这些化合物的结构均经元素分析、UV、~1HNMR和MS鉴定。芳环上不同取代基对卟啉成环反应有一定影响,拉电子基团有利于反应。其顺序如下:NO_2>H>CH_3>OCH_3>N(CH_3)_2。     

Ni2（OEt）2／SiO2催化二氧化碳与丙烯直接合成甲基丙烯酸的研究

 采用表面改性法制备了负载型Ni2（OEt）2／SiO2双核金属乙氧基配合物催化剂，利用示差量热、红外光谱和微反技术对催化剂的表面结构、热稳定性、化学吸附性质和催化活性进行了研究．结果表明，负载型双核金属乙氧基配合物Ni2（OEt）2／SiO2中的Ni2＋与载体SiO2表面的O2－以双齿配位形式键合；二氧化碳在催化剂表面存在桥式吸附态和碳酸单乙酯基物种两种吸附态，丙烯则只有一种分子吸附态；在适宜的反应条件下，二氧化碳和丙烯在Ni2（OEt）2／SiO2催化剂上的反应产物主要是甲基丙烯酸．根据实验结果，提出了二氧化碳和丙烯在Ni2（OEt）2／SiO2催化剂表面的反应机理，反应物分子共吸附于催化剂表面同一活性单元上，羧酸根和丙烯解离吸附态的形成是反应顺利进行的关键步骤．     

聚己内酯聚醚嵌段共聚物和共混物的表面性质对其药物释放行为的影响

聚己内酯聚醚嵌段共聚物和共混物的表面性质对其药物释放行为的影响王卫华，贝建中，王智峰，王身国（中国科学院化学研究所北京１０００８０）关键词聚己内酯聚醚嵌段共聚物，共混物，电子能谱，表面性质，药物释放行为聚己内醋（ＰＣＬ）具有优良的药物通透性和生物相容...     

铑（Ⅲ）与2—（3,5—二氯—2—吡啶偶氮）—5—二甲氨基苯胺络合物的催化氢波

本文提出一种新的测定铑的催化氢波体系.先使Rh(Ⅲ)与3,5-diCl-PADMA在HAc-NaAc缓冲溶液中生成稳定的络合物,再以适量HclO_4将溶液酸化后进行极谱测定。利用正交试验法确定体系的最佳分析条件为:0.05 mol/L pH5.0的HAc-NaAc,1.6×10~(-5)mol/L3,5-diCl-PADMA,沸水浴加热15min.,4.4 mol/L HCIO4酸化。在此条件下的线性范围为1.9×10~(-11)～3.9×10~(-9)mol/L,检出限达5.8×10~(-12)mol/L。大量Cu(Ⅱ)、Ni(Ⅱ)、Fe(Ⅲ)及Co(Ⅱ)对体系的干扰可用EDTA消除。研究了催化波的性质,表明该波为Rh(Ⅲ)与3,5-diClPADMA络合物的催化氢波。     

三组分(NiO、La2O3、SiO2)负载型加氢催化剂中La2O3的作用

用X射线衍射分析、FT-IR、小角X光散射等方法研究了浸渍法制备的NiO/SiO_2和NiO/(La_2O_3+SiO_2)样品中组分之间的相互作用。La_2O_3在SiO_2上可形成近乎密置单层的分散。在负载了La_2O_3的SiO_2上,NiO的分散程度比在SiO_2上有明显提高,也更容易被还原,而且还原后所得金属镍粒子的平均粒度降低,小粒子所占百分比提高。这些结果表明,NiO/(La_2O_3+SiO_2)比NiO/SiO_2样品具有更高的加氢还原硝基普鲁卡因为胺基普鲁卡因的活性,与Ni/(La_2O_3+SiO_2)比Ni/SiO_2活性高的情形相一致。     

EFFECT OF La_2O_3 AND CeO_2 ON CH_4-CO_2 REFORMING NICKEL CATALYST

IntroductionConsiderableattelltionisno\vbeillgpaidtotheCO7refonningof.etha..llto]forseveralreasonst(l)withthedevelopmentofindustrics.moreandnlorcCOZIsabettedintotheatmosphere,leadingto"greenhouseeffect",whichhasbroughtaboutgreatilltcreslallovertheworld.Th…