还原氧化石墨烯负载球形金属酞菁电催化阴极氧还原反应性能

针对阴极氧还原反应(ORR)动力学缓慢和Pt/C类贵金属催化剂成本高等关键难题,我们设计、合成了醛基取代的球形金属酞菁M2Pc2(TA)4(M=Zn、Co、Fe),采用"π-π组装"技术将其负载到还原氧化石墨烯(rGO)上得到复合催化剂M2Pc2(TA)4/rGO,并对其形貌和结构进行表征.结果 表明:通过"π-π堆积...     

聚四氨基钴酞菁膜修饰电极对甲巯咪唑的电催化氧化

用循环伏安法(CV)研究了聚四氨基钴酞菁(CoTAPc)膜修饰电极(p-CoTAPc CME)对甲巯咪唑的电催化氧化行为.在pH=2的缓冲溶液中,与未修饰玻碳电极(GC)相比,甲巯咪唑在p-CoTAPc CME(GC基体)上的氧化峰电位(Vpa)负移220 mV左右,峰电流(Ipa)变为原来的3倍多;还原峰电位(Vpc)正移大约223 mV,峰电流(Ipc)几乎变为裸电极时的6倍.同时,p-CoTAPc CME对甲巯咪唑的电催化氧化活性有很高的稳定性.     

聚血红素修饰电极上氧还原的电催化研究

 采用循环伏安法和电位阶跃法,研究了水溶液中溶解氧在聚血红素修饰电极上还原反应的电催化作用．结果表明,还原峰电流随扫描速度的增大而增强,Ip～v1／2呈线性关系．根据电位阶跃实验的I～t曲线,计算出电极反应的电子转移数约为2,推断其催化机理属于ECE催化过程．     

酞菁钴－高分子双层膜修饰电极对氧的催化电还原

酞菁钴－高分子双层膜修饰电极对氧的催化电还原董国孝，李纪生，庄瑞舫（中国科学院北京化学研究所，北京，１０００８０）（南京大学配位化学研究所）关键词酞菁合钴，双层膜修饰电极，电还原金属酞菁配合物的催化活性和电催化活性已引起化学家们的极大兴趣，它们作为电...     

四羧基酞菁配合物修饰电极对分子氧的电还原

合成了（２，９，１６，２３－四羧基）酞菁（Ｈ２ＴｃＰｃ）及其Ｃｏ（Ⅱ）、Ｒｕ（Ⅲ）、Ｆｅ（Ⅲ）、Ｃｕ（Ⅱ）的配合物（ＣｏＴｃＰｃ、ＲｕＴｃＰｃ、ＦｅＴｃＰｃ、ＣｕＴｃＰｃ），用不可逆吸附法制备了这些化合物的玻碳修饰电极。研究这些修饰电极在酸性和碱性水溶液中对分子氧（Ｏ２）电还原的催化作用，发现酸性水溶液中，ＣｏＴｃＰｃ和ＲｕＴｃＰｃ修饰电极对电还原氧有催化活性，还原产物为过氧化氢；碱性水溶液中，四个配合物修饰电极对电还原氧都有催化活性，其中，ＦｅＴｃＰｃ还原氧的活性较好，它将分子氧（Ｏ２）一步直接还原为水。     

钴卟啉修饰电极对分子氧电催化还原的扫描隧道显微镜研究

利用扫描隧道显微镜(STM)研究了高定向热解石墨(HOPG)和玻璃碳电极(GC)表面的性质, 并对修饰钴卟啉后的表面形貌变化进行了探讨。结合修饰钴卟啉前后的循环伏安结果和STM形貌图, 讨论了电极表面的结构对分子氧的电催化还原反应的影响。从微观角度阐述了GC电极对氧的电催化还原活性明显高于HPOG电极的内在因素,为修饰电极的表面性能研究提供了经验。     

碳化钨电极上氧的电催化还原

以喷雾干燥微球化处理的偏钨酸铵作为前驱体,CO/H2为碳化还原气源,应用固定床气固反应法制备碳化钨(WC)粉体,再以聚四氟乙烯作粘结剂制成碳化钨电极.应用XRD和SEM等表征、观察碳化钨样品,循环伏安和线性扫描法研究硫酸电解液中WC电极的氧还原电催化行为.检测表明,WC为球状颗粒;WC电极对氧还原反应具有较好的电催化活性,硫酸溶液中溶解氧还原反应控制步骤为吸附态(O2-)ads的生成;增加硫酸电解液浓度,开路电位正移,升高温度有利于反应进行.     

碳纳米管的酞菁钴修饰及其对香兰素的电催化性能

通过酰胺化反应制备了四-2,9,16,23-氨基酞菁钴(TAPcCo)与多壁碳纳米管(MWCNTs)的复合材料,红外光谱、扫描电镜和紫外可见吸收光谱分析表明复合材料中酞菁分子与碳管之间是通过酰胺键结合的,紫外吸收光谱还表明两者之间存在着强烈的电子相互作用。同时还研究了复合材料修饰的玻碳电极对香兰素(VNL)的电催化作用。循环伏安法表明,修饰电极对VNL有着良好的电催化活性,相对于裸玻碳电极VNL在修饰电极上峰电位负移了20mV,峰电流增大了12倍,且VNL在电极表面的反应受吸附控制。方波伏安法证实了这一反应过程中有质子参与。同时,方波伏安法研究还发现:峰电流与香兰素浓度在4.2μmol·L-1～5mmol·L-1范围内呈良好的线性关系,检出限(3.3S/N)为0.44μmol·L-1。     

血红素修饰电极及其催化氧还原性质

金属大环络合物（卟啉、酞箐、维生素Ｂ_(１２)等）修饰电极对氧、一氧化氮和其它生物物质的催化作用［１－３］引起了化学工作者的极大兴趣,血红素是一种重要的铁卟啉化合物,是血液中血红蛋白的重要组成部分,承担携氧的任务,由于其特殊的生理功能,研究血红素修饰电极的性质和作用对进一步研究开发燃料电池具有很重大的意义．卟啉在电极上的修饰有多种方法,当卟啉或金属卟啉环侧链上具有苯氨基、苯酚基、乙烯基或吡咯等取代基时［３］,可采用电氧化聚合法制备聚卟啉膜．本文采用循环伏安法在水溶液中制备了聚血红素膜电极,研究了聚…     

钴卟啉的合成及其对氧还原的电催化性能

 合成了四苯基卟啉及其钴配合物,考察了催化剂、溶剂及反应温度等因素对四苯基卟啉收率的影响,并用红外光谱和核磁共振氢谱对合成产物进行了结构表征. 以X射线光电子能谱为主要手段,研究了不同热处理温度对钴卟啉结构的影响,通过测定空气电极极化曲线研究了热处理对钴卟啉催化活性的影响. 结果表明,在200 ℃, 以对硝基苯甲酸为催化剂,硝基苯为溶剂时,四苯基卟啉收率达32%. 热处理能提高金属卟啉的催化活性, 600 ℃热处理后,钴卟啉环中的 Co-N4 结构趋于键断裂的临界状态,催化活性点增多,催化活性较好; 而800 ℃处理的钴卟啉中部分 Co-N4 键破裂,催化活性下降.     

四磺酸基酞菁钴对于光滑Pt电极上氧还原过程的影响

将大环化合物四磺酸基酞菁钴(CoTSPc)加入到电解液中, 研究了其对Pt阴极催化氧还原以及耐甲醇性能的影响. 实验结果发现, 这种影响与加入到溶液中的CoTSPc的浓度有关, 当溶液中加入CoTSPc的浓度为0.09 mmol•L^－1时, Pt电极催化氧还原的电流基本不变, 而有效抑制了甲醇在阴极的氧化, 使甲醇氧化的峰电流值下降79.7%.     

Enhanced Four-Electron Selective Oxygen Reduction Reaction at Carbon-Nanotube-Supported Sulfonic-Acid-Functionalized Copper Phthalocyanine

In the present work, the oxygen reduction reaction (ORR) is explored in an acidic medium with two different catalytic supports (multi-walled carbon nanotubes (MWCNTs) and nitrogen-doped multi-walled carbon nanotubes (NMWCNTs)) and two different catalysts (copper phthalocyanine (CuPc) and sulfonic acid functionalized CuPc (CuPc-SO₃⁻)). The composite, NMWCNTs-CuPc-SO₃⁻ exhibits high ORR activity (assessed based on the onset potential (0.57 V vs. reversible hydrogen electrode) and Tafel slope) in comparison to the other composites. Rotating ring disc electrode (RRDE) studies demonstrate a highly selective four-electron ORR (less than 2.5 % H₂O₂ formation) at the NMWCNTs-CuPc-SO₃⁻. The synergistic effect of the catalyst support (NMWCNTs) and sulfonic acid functionalization of the catalyst (in CuPc-SO₃⁻) increase the efficiency and selectivity of the ORR at the NMWCNTs-CuPc-SO₃⁻. The catalyst activity of NMWCNTs-CuPc-SO₃⁻ has been compared with many reported materials and found to be better than several catalysts. NMWCNTs-CuPc-SO₃⁻ shows high tolerance for methanol and very small deviation in the onset potential (10 mV) between the linear sweep voltammetry responses recorded before and after 3000 cyclic voltammetry cycles, demonstrating exceptional durability. The high durability is attributed to the stabilization of CuPc-SO₃⁻ by the additional coordination with nitrogen (Cu-N_x) present on the surface of NMWCNTs.     

Supramolecular Tuning Enables Selective Oxygen Reduction Catalyzed by Cobalt Porphyrins for Direct Electrosynthesis of Hydrogen Peroxide

We report a supramolecular strategy for promoting the selective reduction of O₂ for direct electrosynthesis of H₂O₂. We utilized cobalt tetraphenylporphyrin (Co‐TPP), an oxygen reduction reaction (ORR) catalyst with highly variable product selectivity, as a building block to assemble the permanently porous supramolecular cage Co‐PB‐1(6) bearing six Co‐TPP subunits connected through twenty‐four imine bonds. Reduction of these imine linkers to amines yields the more flexible cage Co‐rPB‐1(6). Both Co‐PB‐1(6) and Co‐rPB‐1(6) cages produce 90–100 % H₂O₂ from electrochemical ORR catalysis in neutral pH water, whereas the Co‐TPP monomer gives a 50 % mixture of H₂O₂ and H₂O. Bimolecular pathways have been implicated in facilitating H₂O formation, therefore, we attribute this high H₂O₂ selectivity to site isolation of the discrete molecular units in each supramolecule. The ability to control reaction selectivity in supramolecular structures beyond traditional host–guest interactions offers new opportunities for designing such architectures for a broader range of catalytic applications.     

Bifunctional Catalysts for Reversible Oxygen Evolution Reaction and Oxygen Reduction Reaction

Metal-air batteries (MABs) and reversible fuel cells (RFCs) rely on the bifunctional oxygen catalysts for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). Finding efficient bifunctional oxygen catalysts is the ultimate goal and it has attracted a great deal of attention. The dilemma is that a good ORR catalyst is not necessarily efficient for OER, and vice versa. Thus, the development of a new type of bifunctional oxygen catalysts should ensure that the catalysts exhibit high activity for both OER and ORR. Composites with multicomponents for active centers supported on highly conductive matrices could be able to meet the challenges and offering new opportunities. In this Review, the evolution of bifunctional catalysts is summarized and discussed aiming to deliver high-performance bifunctional catalysts with low overpotentials.     

Inhibition of Reduction Current of Oxygen by Cysteine and Glutathione at Smooth Platinum Electrodes

Abstract

The reduction of molecular oxygen is inhibited by the chemisorption of cysteine and glutathione on the smooth platinum electrode. The cathodic current of the molecular oxygen reduction is dependent on the concentration of both substances.     

Electrocatalytic Dioxygen Reduction by Carbon Electrodes Noncovalently Modified with Iron Porphyrin Complexes: Enhancements from a Single Proton Relay

Oxygen reduction in acidic aqueous solution mediated by a series of asymmetric iron (III)‐tetra(aryl)porphyrins adsorbed to basal‐ and edge‐ plane graphite electrodes is investigated. The asymmetric iron porphyrin systems bear phenyl groups at three meso positions and either a 2‐pyridyl, a 2‐benzoic acid, or a 2‐hydroxyphenyl group at the remaining meso position. The presence of the three unmodified phenyl groups makes the compounds insoluble in water, enabling catalyst retention during electrochemical experiments. Resonance Raman data demonstrate that catalyst layers are maintained, but can undergo modification after prolonged catalysis in the presence of O₂. The introduction of a single proton relay group at the fourth meso position makes the asymmetric iron porphyrins markedly more robust catalysts; these molecules support higher sustained current densities than the parent iron tetraphenylporphyrin. Iron porphyrins bearing a 2‐pyridyl group are the most active catalysts and operate at stable current densities ≥1 mA cm^?2 for over 5 h. Comparative analysis of the catalysts with different proton relays also is reported.     

Characterization of the Reduction of Oxygen at Anthraquinone-Modified Glassy Carbon and Highly Oriented Pyrolytic Graphite Electrodes

1-(N-Boc-aminomethyl)-4-(aminomethyl)benzene, bearing a protected amine group, was electrochemically grafted to glassy carbon and edge plane and basal plane highly oriented pyrolytic graphite electrodes by the oxidation of the corresponding linker. Following the removal of tert-butyloxycarbonyl protecting group, anthraquinone-2-carboxylic acid was coupled to the amine-terminated linker using solid-phase synthesis. The surface coverage of the immobilized anthraquinone redox centers was investigated by cyclic voltammetry and found to be the highest at edge plane and the lowest at the basal plane electrodes. The electrocatalytic activity of the anthraquinone-modified electrodes toward oxygen reduction was explored by cyclic voltammetry, chronoamperometry, and chronocoulometry at the unmodified and modified graphite electrodes. The immobilized anthraquinone was shown to catalyze the reduction of oxygen to hydrogen peroxide and the number of electrons transferred was two for all modified electrodes.     

酞菁钴催化剂载体表面含氮官能团对其在燃料电池中氧还原性能的影响

以酞菁钴为催化剂,纳米碳管为载体,分别通过超声法和四氢呋喃法混合分散,并在氮气氛围高温热处理制备了两种酞菁钴催化剂.热重分析（TGA）结果显示超声法制备的酞菁钴催化剂（CoPc-CNT-S）含钴的质量分数为8.1 wt%,四氢呋喃混合法制备的酞菁钴催化剂（CoPc-CNT-R）含钴的质量分数为7.0 wt%.X射线光电子谱（XPS）结果显示CoPc-CNT-R催化剂的含氮量是CoPc-CNT-S催化剂的两倍多,且两种催化剂含氮官能团的种类及比例不同.相比较而言,CoPc-CNT-S表面有更多的吡咯型氮.将两种催化剂应用于混合酸碱燃料电池中发现：CoPc-CNT-S对电催化氧还原有较高的活性和稳定性,将CoPc-CNT-S作为燃料电池的阴极催化剂分别工作5 h和15 h后,电荷转移电阻相对CoPc-CNT-R为阴极催化剂时均较低.原因可能是相近比例的吡啶型N和吡咯型N的协同作用有利于电催化氧还原.