Fe, N, S-doped porous carbon as oxygen reduction reaction catalyst in acidic medium with high activity and durability synthesized using CaCl2 as template

燃料电池是一种可将化学能通过电催化反应直接转化成电能的装置,具有能量密度高和清洁无污染等优点.燃料电池阴极氧还原反应(ORR)的动力学较迟缓,是; 电池能量效率损失的主要原因.目前ORR催化活性最高的是铂基催化剂,但由于贵金属铂价格昂贵,储量稀少,且对燃料小分子渗透的抗性较差,严重制约了燃料; 电池的大规模应用.因此,高性能、低成本的非贵金属催化剂成为燃料电池领域的研究热点.本文选用含氮量高达45%的三聚氰胺-甲醛树脂为碳源和氮源,Fe; (SCN)_3为铁源和硫源,以CaCl_2为模板,在高温和铁的催化作用下将树脂碳化,经酸洗和二次热处理工艺,制备出铁、氮、硫共掺杂的多孔碳(Fe; NS-PC).干燥后的CaCl_2颗粒可防止树脂在高温下交联形成块状碳颗粒,同时起到造孔模板的作用.CaCl_2颗粒在温和条件下即可除去,无需强; 腐蚀性条件,因此不会对催化活性中心造成破坏.在Fe/N/C催化剂中掺杂S可进一步提高催化活性,不添加碳载体可避免低活性的碳载体降低质量活性,多孔; 结构可促进传质,充分利用活性位点.我们优化了热处理温度,并对催化剂的结构、组分及催化性能等进行了表征分析.结果表明,热处理温度为900; °C时,可将树脂完全转化成多孔碳,并获得较高的杂原子掺杂量,可达到最优活性.CaCl_2为模板剂可避免使用强腐蚀性试剂去除模板,有利于保留活性位; ,并得到多孔结构.FeNS-PC-900的比表面积可达775; m~2/g.得益于原位掺杂的合成工艺,各掺杂元素在多孔碳表面均匀分布.在酸性介质中,FeNS-PC-900的半波电位可达到0.811; V,仅比商业Pt/C催化剂低78 mV;在0.8 V电位下的质量活性为10.2; A/g,表现出优异的催化活性.经过10000圈加速衰减测试后,其半波电位仅下降了20 mV,在0.75 V电位下持续放电10000; s后,其ORR电流仍保持初始电流的84.4%,具有比Pt/C更加优异的稳定性.以FeNS-PC-900为阴极催化剂的质子交换膜燃料电池的最大功率; 密度可达到0.49 W/cm~2,并在0.6 V电压下持续放电10; h后,其电流仍可保持初始电流的65%,表现出良好的应用潜力.FeNS-PC-900具有高掺杂含量、高比表面积和多孔结构,并且杂原子在催化剂表面均; 匀分散,在半电池和燃料电池测试中都表现出优异的催化活性和稳定性,表明其是一种非常有潜力应用于燃料电池的非贵金属氧还原催化剂.Proton exchange membrane fuel cells suffer from the sluggish kinetics of the oxygen reduction reaction (ORR) and the high cost of Pt catalysts. In the present work, a high-performance ORR catalyst based on Fe, N, S-doped porous carbon (FeNS-PC) was synthesized using melamine formaldehyde resin as C and N precursors, Fe(SCN)(3) as Fe and S precursors, and CaCl2 as a template via a two-step heat treatment without a harsh template removal step. The results show that the catalyst treated at 900 degrees C (FeNS-PC-900) had a high surface area of 775 m(2)/g, a high mass activity of 10.2 A/g in an acidic medium, and excellent durability; the half-wave potential decreased by only 20 mV after 10000 potential cycles. The FeNS-PC-900 catalyst was used as the cathode in a proton exchange membrane fuel cell and delivered a peak power density of 0.49 W/cm(2). FeNS-PC-900 therefore has good potential for use in practical applications. (C) 2017, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.National Basic Research Program of China [2015CB932303]; National; Natural Science Foundation of China [21373175, 21621091

Study of the host-guest interaction between: N, N ′-bis[4-(dimethylaminophenyl)methyl]butane-1,4-diamine and the cucuribit [n] urils (n = 6, 7)

The interaction between the cucuribit[n]urils (Q[n]), where n = 6 or 7, and the guest N,N/-bis[4-(dimethylaminophenyl)methyl]butane-1,4-diamine (G) has been studied in aqueous solution by 1H NMR spectroscopy, electronic absorption spectroscopy and Isothermal Titration Calorimetry (ITC). In the case of Q[6], a 1:1 host-guest complex is favoured with on end of G initially embedded in the Q[6], although over time (48h), the Q[6] shuttles along the chain such that it resides over the centre of G. For Q[7], a 2:1 host-guest complex is formed with the aromatic groups at each end of G buried in a Q[7] cavity. The molecular structure of the inclusion complex having composition overall composition of Q[6].GH2.2Cl.14H2O has been determined, and clearly shows the insertion of the guest molecule with the host Q[6] and it is localised therein by two N-H∙∙∙O hydrogen bonds

Association between Single Nucleotide Polymorphisms in SIRT1 and SIRT2 Loci and Growth in Tibetan Sheep

Silent information regulator 1 and 2 (SIRT1, 2) were NAD+-dependent histone or non-histone deacetylase, which emerged as key metabolic sensors in several tissues of mammals. In the present study, the search for polymorphisms within the ovine SIRT1 and SIRT2 loci as well as association analyses between SNPs and growth-related traits were performed in Tibetan sheep. To determine the expression pattern of SIRT1 and SIRT2 genes in Tibetan sheep, the quantitative real-time polymerase chain reaction (qPCR) analysis revealed that those two genes were widely expressed in diverse tissues. Expression of SIRT1 was less in abomasum of lamb, whereas it was greater in duodenum within adult stage. In the case of SIRT2, the greatest expression was observed in reticulum (lamb) and in muscle (adult), whereas the least expression was in liver for lamb and in kidney for adult animals. The association analysis demonstrated that g.3148 C \u3e T polymorphism of SIRT1 affected heart girth (p = 0.002). The g.8074 T \u3e A SNP of SIRT2 had a significant correlation with body weight (p = 0.011) and body length (p = 0.008). These findings suggested that the SIRT1 and SIRT2 polymorphism was involved in growth-related traits in Tibetan sheep, which may be considered to be genetic markers for improving the growth traits of Tibetan sheep

KOH-doped polybenzimidazole membrane for direct hydrazine fuel cell.

Alkaline direct hydrazine (N2H4) fuel cells (DHFCs) are considered one of the most promising liquid-fed fuel cells because of their high energy density, high theoretical voltage, and zero carbon dioxide (CO2) emissions. However, the lack of a suitable electrolyte membrane impedes the further development of alkaline DHFC. Herein, a potassium hydroxide (KOH)-doped polybenzimidazole (PBI) membrane is applied in alkaline DHFCs, and the detailed operating conditions are investigated for the first time. With optimal KOH and N2H4 concentrations in the anolyte, membrane thickness, and cathode gas humidity, the DHFC gives a peak power density of 0.708 W cm-2. The results of this study demonstrate the promising application of PBI membranes in DHFC and provide a platform to evaluate the performance of catalysts synthesized for DHFC

KOH-doped polybenzimidazole membrane for direct hydrazine fuel cell

Abstract(#br)Alkaline direct hydrazine (N 2 H 4 ) fuel cells (DHFCs) are considered one of the most promising liquid-fed fuel cells because of their high energy density, high theoretical voltage, and zero carbon dioxide (CO 2 ) emissions. However, the lack of a suitable electrolyte membrane impedes the further development of alkaline DHFC. Herein, a potassium hydroxide (KOH)-doped polybenzimidazole (PBI) membrane is applied in alkaline DHFCs, and the detailed operating conditions are investigated for the first time. With optimal KOH and N 2 H 4 concentrations in the anolyte, membrane thickness, and cathode gas humidity, the DHFC gives a peak power density of 0.708 W cm −2 . The results of this study demonstrate the promising application of PBI membranes in DHFC and provide a platform to evaluate the performance of catalysts synthesized for DHFC

Pd-Pt random alloy nanocubes with tunable compositions and their enhanced electrocatalytic activities

Monodisperse, highly-selective sub-10 nm Pd-Pt random alloy nanocubes have been successfully synthesized in aqueous solution, and the electrocatalytic activity of these Pd-Pt alloys towards formic acid oxidation was investigated and compared with the activity of Pd sub-10 nm nanocubes, and the commercial Pd and Pt black.NSFC [20725102, 20921001]; Fok Ying Tung Education Foundation [111012]; State Key Project of Fundamental Research for Nanoscience and Nanotechnology [2006CB932301

In situ time-resolved FTIRS study of adsorption and oxidation of ethylene glycol on Pt(100) electrode

Adsorption and oxidation of ethylene glycol (EG) on Pt(100) electrode were studied by in situ time-resolved FTIRS (TRFTIRS). The TRFTIR spectra recorded at 0.10 V illustrate that an IR band appears near 2050 cm(-1) at t > 5 s, corresponding to linearly bonded CO formed in dissociative adsorption of EG The TRFTIR results have confirmed also that CO species are distributed uniformly on Pt(100) surface. Another band appears near 2342 cm(-1) at t < 70 s, associating with IR absorption of CO2 produced in the direct oxidation of EG With the increase of electrode potential, the direct oxidation of EG becomes gradually the main reaction. When the potential is above 0.40 V, the oxidation of EG occurs mainly via the reactive intermediates, i.e. species containing -COOH determined by in situ TRFTIRS

Controlled Formation of Concave Tetrahedral/Trigonal Bipyramidal Palladium Nanocrystals

通讯作者地址: Zheng, NF (通讯作者), Xiamen Univ, State Key Lab Phys Chem Solid Surfaces, Xiamen 361005, Peoples R China 地址: 1. Xiamen Univ, State Key Lab Phys Chem Solid Surfaces, Xiamen 361005, Peoples R China 2. Xiamen Univ, Dept Chem, Coll Chem & Chem Engn, Xiamen 361005, Peoples R China 电子邮件地址: [email protected] concave Pd nanocrystals with uniform diameter were successfully prepared in the presence of formaldehyde. While the outer surfaces of the as-prepared concave Pd nanocrystals are {111}, the faces concave toward the polyhedral. center are high-surface-energy {110} faces. The degree of concavity and therefore the percentage of {110} of the nanocrystals are tunable by varying the amount of formaldehyde and the reaction temperature. Owing to the existence of active {110} facets, the electrocatalytic activity of the concave Pd nanocrystals displays dependency on their degree of concavity.NSFC20871100,20721001 MSTC 92009CB930703 RFDP 200803841010 NSF 2009J06005 Fujian Province 2009HZ0002-

Electrocatalytic Activity of Palladium Nanocatalysts Supported on Carbon Nanoparticles in Formic Acid Oxidation

采用化学还原法制备了碳纳米粒子支撑的钯纳米结构(Pd-CNP). 透射电镜表征显示在Pd-CNP纳米复合物中，金属Pd呈菜花状结构，粒径约20~30 nm。它们由许多更小的Pd纳米粒子（3~8 nm）组成. 电化学研究表明，虽然Pd-CNP的电化学活性面积比商业Pd黑低40%（可能原因是部分Pd表面被一层碳纳米粒子覆盖），但其对甲酸氧化却表现出更好的电催化活性：质量比活性和面积比活性都比Pd黑高几倍. 催化活性增强的原因可能是碳纳米粒子支撑的Pd纳米结构具有特殊的层次化结构，可以形成更多的活性位，以及表面位更利于反应进行.Palladium nanostructures were deposited onto carbon nanoparticle surface by a chemical reduction method. Transmission electron microscopic studies showed that whereas the resulting metal-carbon (Pd-CNP) nanocomposites exhibited a diameter of 20 to 30 nm, the metal components actually showed a cauliflower-like surface morphology that consisted of numerous smaller Pd nanoparticles (3 to 8 nm). Electrochemical studies showed that the effective surface area of the Pd-CNP nanoparticles was about 40% less than that of Pd black, possibly because the Pd nanoparticles were coated with a layer of carbon nanoparticles; yet, the Pd-CNP nanocomposites exhibited marked enhancement of the electrocatalytic activity in formic acid oxidation, as compared to that of Pd black. In fact, the mass- and surface-specific activities of the former were about three times higher than those of the latter. This improvement was likely a result of the enhanced accessibility of the Pd catalyst surface and the formation of abundant active sites of Pd on the carbon nanoparticle surface due to the hierarchical structure of the metal nanocatalysts.This work was supported, in part, by the National Science Foundation (CHE&ndash;1012256 and DMR&ndash;0804049) and by the ACS-Petroleum Research Fund (49137&ndash;ND10). J. H. was supported, in part, by a research fellowship from the China Scholarship Council. TEM work was performed as a User Project at the National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, which is supported by the US Department of EnergyThis work was supported, in part, by the National Science Foundation (CHE&ndash;1012256 and DMR&ndash;0804049) and by the ACS-Petroleum Research Fund (49137&ndash;ND10). J. H. was supported, in part, by a research fellowship from the China Scholarship Council. TEM work was performed as a User Project at the National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, which is supported by the US Department of Energy作者联系地址：1. 加利福尼亚大学化学与生物化学系，美国 圣克鲁兹 95064; 2. 西北工业大学凝固技术国家重点实验室，陕西 西安710072Author's Address: 1. Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, United States; 2. State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi&rsquo;an 710072, China通讯作者E-mail：[email protected]