新颖无机质子传导材料的研究进展

质子传导在燃料电池、气体传感及电致显色等领域有重要的研究前景.尤其是在燃料电池领域,由于其具有低污染、高效率、操作简单和寿命长等优点而被广泛应用.本文介绍了质子传导在质子交换膜燃料电池中的重要作用及工作原理,分析了质子交换膜的质子传导机理,并简要分析总结了近年来关于无机及其复合质子导体材料的研究进展.     

Water uptake and infrared absorption in SrZr<Subscript>0.95</Subscript>M<Subscript>0.05</Subscript>O<Subscript>3-</Subscript><Subscript>a</Subscript> (<Emphasis Type="Italic">M</Emphasis>=Ga,Sc, Y and Nd)

Summary Proton concentration in SrZr_0.95M_0.05O_3-α (M=Ga, Sc, Y and Nd) was measured with a thermobalance at different temperatures (T=673-973 K) and water vapor pressures (P_H2O=0.9-12.8 kPa). At all the pressures and temperatures examined, the amount of proton concentration in these samples is in the order of Sc>Y>Ga>Nd. By an equilibrium evaluation, we estimated the maximum possible proton concentration about 2.0 mol% in these samples. Infrared (IR) absorption spectra are measured in these samples. The absorption bands can be fitted by four (M=Ga, Y, Nd) or three (M=Sc) Gaussian bands.     

Proton mobility in hydrates of inorganic acids and acid salts

Published data on the mechanisms of hydrogen ion transport in solids and aqueous solutions are described systematically, including defect formation, rotational mobility of proton-containing groups, proton hopping along a hydrogen bond, proton translational mobility, and proton conduction. Resorting to the authors" theoretical results and published data, the main criteria for the selection of systems possessing high proton mobility are formulated.     

基于杂多酸的固体高质子导体*

杂多酸固体高质子导体在燃料电池、传感器和电显色装置等方面具有潜在的应用前景。本文概述了杂多酸的质子导电性,归纳了其质子导电性的一些规律,以表格形式列举了各类杂多酸的电导率。将不同质量分数的杂多酸固载在各类固体基质上,可以对杂多酸质子导电材料改性以便于工业中实际应用。这些杂化材料兼有杂多酸的高质子导电性以及基质的稳定性与机械延展性。本文综述了近几年来新型杂多酸,杂多酸-无机基质复合材料,杂多酸-有机基质复合材料,杂多酸-多元基复合材料的质子电导率、稳定性、结构形态等等方面的研究进展,详细介绍了杂多酸在质子交换膜燃料电池中的应用,并对杂多酸固体高质子导体的应用前景进行了展望。     

On stability and protonation of multielectron systems: The concept of proton affinity. II. Dissociative proton attachment and protonation—Deprotonation mapping

A few touches on the thematic palette “molecular protonation” directly linked to the concept of molecular stability have been accomplished. They are of different nature, of different origin, and taken from “different angles” of lighting; however, together, they definitely provide a sufficiently complete picture “The protonation interaction, as being strong enough, may break the stability of molecules subject to protonation.” © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012     

细胞色素c氧化酶研究新进展

综述了细胞色素c氧化酶研究的新进展,重点评述了细胞色素c氧化酶晶体结构和各种谱学研究结果,质子传递途径、O2还原的催化机理以及与其相耦联的质子泵机理等方面的最新进展。     

Synthesis and Characterization of Sulfonated Polyimides Containing Trifluoromethyl Groups as Proton Exchange Membranes

A novel sulfonated diamine, 4,4′‐bis(4‐amino‐3‐trifluoromethylphenoxy) biphenyl 3,3′‐disulfonic acid (F‐BAPBDS), was successfully synthesized by nucleophilic aromatic substitution of 4,4′‐dihydroxybiphenyl with 2‐chloro‐5‐nitrobenzotrifluoride, followed by reduction and sulfonation. A series of sulfonated polyimides of high molecular weight (SPI‐x, x represents the molar percentage of the sulfonated monomer) were prepared by copolymerization of 1,4,5,8‐naphathlenetetracarboxylic dianhydride (NTDA) with F‐BAPBDS and nonsulfonated diamine. Flexible and tough membranes of high mechanical strength were obtained by solution casting and the electrolyte properties of the polymers were intensively investigated. The copolymer membranes exhibited excellent oxidative stability due to the introducing of the CF₃ groups. The SPI membranes displayed desirable proton conductivity (0.52×10⁻¹–0.97×10⁻¹ S·cm⁻¹) and low methanol permeability (less than 2.8×10⁻⁷ cm²·s⁻¹). The highest proton conductivity (1.89×10⁻¹ S·cm⁻¹) was obtained for the SPI‐90 membrane at 80°C, with an IEC of 2.12 mequiv/g. This value is higher than that of Nafion 117 (1.7×10⁻¹ S·cm⁻¹). Furthermore, the hydrolytic stability of the obtained SPIs is better than the BDSA and ODADS based SPIs due to the hydrophobic CF₃ groups which protect the imide ring from being attacked by water molecules, in spite of its strong electron‐withdrawing behaviors.     

Synthesis and properties of novel polyimides from sulfonated binaphthalene dianhydride for proton exchange membranes

A sulfonated dianhydride monomer, 6,6′‐disulfonic‐4,4′‐binaphthyl‐1,1′,8,8′‐tetracarboxylic dianhydride (SBTDA), was successfully synthesized by direct sulfonation of the parent dianhydride, 4,4′‐binaphthyl‐1,1′,8,8′‐tetracarboxylic dianhydride (BTDA), using fuming sulfuric acid as the sulfonating reagent. A series of sulfonated homopolyimides were prepared from SBTDA and various common nonsulfonated diamines. The resulting polymer electrolytes, which contain ion conductivity sites on the deactivated positions of the aryl backbone rings, displayed high proton conductivities of 0.25–0.31 S cm^?1 at 80 °C. The oxidative stability test indicated that the attachment of the ? SO₃H groups onto the dianhydride units did not deteriorate the oxidative stability of the SPI membranes. The better membranes were achieved by the copolymerization of nonsulfonated diamine, SBTDA, and BTDA. Copolymer membrane synthesized from hexane‐1,6‐diamine, SBTDA, and BTDA displayed excellent water stability of more than 1000 h at 90 °C, while its proton conductivity was still at a high level (comparable to that of Nafion 117). Furthermore, the novel block copolymer ( II‐b ) displayed higher proton conductivity compared with the random one ( II‐r ) obviously, probably due to the slightly higher water uptake and better microphase separated morphology. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2820–2832, 2008     

Intra- and intermolecular proton transfer reactions in 2-phenyl substituted benzazoles

The present review describes the salient features of inter- and intramolecular proton transfer reactions of 2-(2′-aminophenyl)-, 2-(3′-aminophenyl)-, 2-(4′-aminophenyl)-, 2-(2′-hydroxyphenyl)-, 2-(3′-hydroxyphenyl)- and 2-(4′-hydroxyphenyl)-benzimidazoles, benzoxazoles and benzothiazoles. Fluorescence quantum yield of the phototautomer produced by the intramolecular hydrogen bonding decreases on going from benzimidazole to benzoxazole to benzothiazole. This indicates that the rate of internal conversion increases in the order of compounds as mentioned above. The biprotonic phototautomerism or the presence of intermolecular proton transfer has led to the formation of (i) nonfluorescent zwitterions in case of hydroxyphenyl derivatives and the ground state precursor of this species in neutral molecules, (ii) nonfluorescent monoanions from fluorescent monoanions and (iii) nonfluorescent monocations from monocations in case of aminophenyl derivatives. In the case of 2-(4′-aminophenyl)-substituted compounds, the first protonation has always led to the formation of two types of monocations; one by protonating the amino group and the other by protonating the tertiary nitrogen atom. The former is more stable in aqueous media and the latter in non-polar media.     

Excited-state proton transfer from pyranine to acetate in methanol

Excited-state proton transfer (ESPT) of pyranine (8-hydroxypyrene-1,3,6-trisulphonate, HPTS) to acetate in methanol has been studied by steady-state and time-resolved fluorescence spectroscopy. The rate constant of direct proton transfer from pyranine to acetate (k ₁) is calculated to be ∼1 × 10⁹ M⁻¹ s⁻¹. This is slower by about two orders of magnitude than that in bulk water (8 × 10¹⁰ M⁻¹ s⁻¹) at 4 M acetate.     

Proton conductivity of membranes based on the sulfocationites MSC-H and purolite CT-275

The proton conductivity properties of new heterogeneous membranes based on the sulfocationites MSC-H and Purolite CT-275, which are stable in polar media, have been studied. The specific proton conductivity of the membranes were (1–2.3)·10⁻⁴ S/cm at 75–95 °C. The value of the proton conductivity is determined by the exchange capacity of the membranes and the structure of the hydration shell of the transported proton. The latter depends on the temperature, the relative humidity, and the current intensity through the membrane. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 43, No. 1, pp. 52–57, January–February, 2007.     

2-取代咪唑衍生物掺杂高温非水用Nafion质子交换膜的制备和性能

高温质子交换膜燃料电池所面临的一个主要技术障碍是高温低湿度环境下能够具有满足电池工作条件的膜的制备.本文通过所合成的2-取代咪唑衍生物与全氟磺酸树脂的掺杂,采用溶液重铸法制备了可以在高温无水条件下工作的质子交换膜.通过2-位疏水基团的接枝,实现了非水质子传导介质的咪唑环在膜内的固定,所制备的复合质子交换膜的导质子率在160℃无水条件下达到6.8×10^-3Scm^-1;而且相比全氟磺酸均质膜,其热稳定性也有所提高.采用静电力显微镜观察到了所制备的复合质子交换膜内相互连接的离子团簇的形成;结合其质子传导活化能,提出了所制备的复合质子交换膜在120℃以下质子传导以跳跃方式为主;在120℃以上,则以咪唑环的＂钟摆＂形式实现质子在膜内的传输.     

金属有机框架质子导体及其质子交换膜的研究进展

质子交换膜是新型燃料电池的关键组件之一.以Nafion为代表的商用全氟磺酸质子交换膜成本较高、操作温度较低,限制了宽温度范围下的大规模应用.金属有机框架材料（Metal Organic Framework,MOFs）因其比表面积大、结构规整、可设计性强等优点,在质子交换领域备受关注.作者从三方面综述了MOFs质子导体的相关研究.第一部分主要介绍了MOFs传导质子的作用机理;第二部分从有水/无水条件下工作的两种不同MOFs出发综述了MOFs质子导体的相关发展;第三部分系统回顾了MOFs质子交换膜的相关研究,包括MOFs薄膜与MOFs混合基质膜结构.最后指出了MOFs质子导体及其质子交换膜研究中尚未解决的问题,并展望该领域的未来研究方向.     

Different Protonation Equilibria of 4‐Methylimidazole and Acetic Acid

Dynamic protonation equilibria in water of one 4‐methylimidazole molecule as well as for pairs and groups consisting of 4‐methylimidazole, acetic acid and bridging water molecules are studied using Q‐HOP molecular dynamics simulation. We find a qualitatively different protonation behavior of 4‐methylimidazole compared to that of acetic acid. On one hand, deprotonated, neutral 4‐methylimidazole cannot as easily attract a freely diffusing extra proton from solution. Once the proton is bound, however, it remains tightly bound on a time scale of tens of nanoseconds. In a linear chain composed of acetic acid, a separating water molecule and 4‐methylimidazole, an excess proton is equally shared between 4‐methylimidazole and water. When a water molecule is linearly placed between two acetic acid molecules, the excess proton is always found on the central water. On the other hand, an excess proton in a 4‐methylimidazole‐water‐4‐methylimidazole chain is always localized on one of the two 4‐methylimidazoles. These findings are of interest to the discussion of proton transfer along chains of amino acids and water molecules in biomolecules.     

Block copolystyrene derivatives having flexible alkylsulfonated side chains and hydrophobic alkoxy chains as a proton exchange membrane for fuel cell application

A series of block copolystyrene derivatives, poly{[4‐(4‐sulfobutyloxy)styrene]_x‐block‐[4‐(n‐butoxystyrene)]_y} (PSBOS_x‐b‐PnBOS_y), containing a flexible alkylsufonated side chain and hydrophobic alkoxy chain with various ion exchange capacities (IECs) have been synthesized based on living anionic polymerization. The resulting crosslinked membranes were prepared using 4,4′‐methylene‐bis[2,6‐bis(hydroxyethyl)phenol] as the crosslinker in the presence of methanesulfonic acid. The crosslinked PSBOS_2.2‐b‐PnBOS₁ membrane with IEC of 2.89 mequiv g^?1 displays a high proton conductivity (0.01 S cm^?1) at 30% relative humidity and 80 °C, which is comparable to that of Nafion. The well‐developed phase separation and the continuous hydrophilic domains in the crosslinked PSBOS_2.2‐b‐PnBOS₁ membranes have been observed in a transmission electron microscope image. Moreover, the dynamic mechanical analysis measurement and Fenton's reagent testing show that the crosslinked PSBOS_x‐b‐PnBOS_y membranes have good mechanical properties and oxidative stability. These results indicate that the introduction of flexible alkylsulfonated side chains to the polystyrene main chains positively affect both the proton conductivity and oxidative stability. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

IR spectroscopic properties of H(MeOH)n + clusters in the liquid phase: evidence for a proton wire

The long-standing problem of understanding the nature of the "excess proton" in acidified water is simplified by studying the proton in methanol. The 3D network of hydrogen bonds in H(aq) + is reduced to a 1D problem. Infrared spectroscopic characterization of linear chain methanol proton solvates in H(CH3OH)n + for n=2-8 provides insight into some of the puzzling IR spectral features associated with O-H-O vibrations. These include the virtual disappearance of otherwise strong bands from H-bonded methanol molecules adjacent to symmetrical O-H+-O groups. The data indicate that a chain of up to four O--HO bonds either side of this group can act as an electrical wire to separate positive charge. This suggests a refinement of the Grotthuss proton-hopping mechanism for explaining the anomalously high mobility of H+ in H-bonded media.     

Energy material - the role of silicotungstic acid and fly ash in sulfonated poly (ether sulfone) composites for PEMFC applications

The composite polymer electrolyte membranes were prepared from sulfonated poly (ether sulfone) (SPES), silicotungstic acid (STA) and fly ash (FA). Post sulfonation process was adopted to synthesize SPES using sulphuric and chlorosulfonic acid. The prepared electrolyte membranes were examined by water uptake capacity, swelling ratio, ion-exchange ability, proton conductivity, thermal stability and electrochemical performance for evaluating the pertinence of these membranes in fuel cell applications. As such the pristine membrane restricts with the proton conductivity of 0.042?S cm^?1 at 30?°C and 0.060?S cm^?1 at 90?°C while the polymer composite membrane, SP-STA-FA-10 reveals the maximum conductivity of 0.054?S cm^?1 at 30?°C and 0.073?S cm^?1 at 90?°C. It also exhibits good thermal stability than that of the pure membrane. The membrane electrode assemblies (MEAs) have been successfully developed from SPES as well as SP-STA-FA-10 membranes and their electrochemical performance were studied the wide range of current density. Herein, the composite membranes derived from SPES, STA and FA can be viable candidates for fuel cell applications.     

Energy barriers of proton transfer reactions between amino acid side chain analogs and water from ab initio calculations

Proton transfer reactions were studied in all titratable pairs of amino acid side chains where, under physiologically reasonable conditions, one amino acid may function as a donor and the other one as an acceptor. Energy barriers for shifting the proton from donor to acceptor atom were calculated by electronic structure methods at the MP2/6-31++G(d,p) level, and the well-known double-well potentials were characterized. The energy difference between both minima can be expressed by a parabola using as argument the donor-acceptor distance R(DA). In this work, the fit parameters of the quadratic expression are determined for each donor-acceptor pair. Moreover, it was found previously that the energy barriers of the reactions can be expressed by an analytical expression depending on the distance between donor and acceptor and the energy difference between donor and acceptor bound states. The validity of this approach is supported by the extensive new data set. This new parameterization of proton transfer barriers between titratable amino acid side chains allows us to very efficiently estimate proton transfer probabilities in molecular modelling studies or during classical molecular dynamics simulation of biomolecular systems.     

A Phosphate-Based Silver–Bipyridine 1D Coordination Polymer with Crystallized Phosphoric Acid as Superprotonic Conductor

Phosphate-based silver–bipyridine (Ag-bpy) 1D coordination polymer {[{Ag(4,4′-bpy)}₂{Ag(4,4′-bpy)(H₂PO₄)}] ⋅ 2 H₂PO₄ ⋅ H₃PO₄ ⋅ 5 H₂O}_n ( 1 ) with free phosphoric acid (H₃PO₄), its conjugate base (H₂PO₄⁻) and water molecules in its lattice was synthesized by room-temperature crystallization and the hydrothermal method. An XRD study showed that coordinated H₂PO₄⁻, lattice H₂PO₄⁻ anions, free H₃PO₄ and lattice water molecules are interconnected by H-bonding interactions, forming an infinitely extended 2D H-bonded network that facilitates proton transfer. This material exhibits a high proton conductivity of 3.3×10⁻³ S cm⁻¹ at 80 °C and 95 % relative humidity (RH). Furthermore, synthesis of this material from commercially available starting materials in water can be easily scaled up, and it is highly stable under extreme conditions of conductivity measurements. This report inaugurates the usage and design principle of proton-conducting frameworks based on crystallized phosphoric acid and phosphate.