Peculiar reactions between interstitial compounds of transition metals and hydrogen peroxide and characterization of resultant materials

研究发现，碳化钨与过氧化氢反应生成的过氧草酸-聚钨酸盐等氧化钨团簇具有较高的质子导电性。在本财政年度，他们研究了将这种簇合物引入有机基质以提高化学稳定性的方法，并对所获得的纳米杂化材料作为质子导电固体电解质膜进行了评估。我们通过一水合三氧化钨与过氧化氢在40℃下反应24小时得到了过氧钨酸盐络合物的均相溶液。在溶液中加入草酸、丙二酸或二甲基丙二酸等羧酸，以0.25%-4.0%的比例与钨原子形成络合物。将该溶液加入醇氧基硅烷化聚氧乙烷的甲醇溶液中，并在60℃下通过溶胶凝胶法进行聚合。在缝合水蒸气压力下，在25-160℃的温度范围内，用交流阻抗法测量了膜的质子电导率。在80℃下，典型膜的电导率为1.4×10~(-2)~(-2)·Scm~(-1)，是由聚氧化乙烯和二水三氧化钨简单混合制成的无机高质子导体复合膜的10倍。这意味着钨酸盐团簇以纳米级的均匀分布在整个PEO基质中，形成了快速质子传输的渗流路径。振动光谱和X射线衍射谱也证实了这一点。尽管电导率在100℃以上随温度升高而下降，但在140-160℃范围内保持在10scm-1的水平。体积较大的配体，如二甲基丙二酸酯，往往会抑制高温下的电导率下降。

It has been found that some tungsten oxide clusters like peroxo-oxalato-polytungstate formed by a reaction of tungsten carbide with hydrogen peroxide show high proton conductivity. In this fiscal year have studied a methodology to incorporate such a cluster into an organic matrix to enhance chemical stability, and evaluated nanohybrid materials thus obtained as a proton conductive solid electrolyte membrane.We obtained a homogeneous solution of a peroxotungstate complex by reacting tungsten trioxide monohydrate with hydrogen peroxide at 40℃ for 24 h. A carboxylic acid such as oxalic, malonic or dimethylmalonic acid was added to the solution at the ratio of 0.25-4.0 to tungsten atom, to yield a chelated complex. This solution was added to a methanol solution of alchoxysillilated poly (ethyleneoxide)-600 and polymerized at 60℃ by a sol-gel process. A homogeneous and transparent membrane was formed.Proton conductivity of those membranes was measured in the temperature range of 25-160℃ under suturated water vapor pressure by the ac impedance method. Conductivity of a typical membrane at 80℃ was 1.4x10^<-2> Scm-1, which was 10 times higher that that of a composite membrane fabricated by simply blending PEO and tungsten trioxide dihydrate as an inorganic high proton conductor. This means that tungstate clusters dispersed at a nano-level homogeneity throughout the PEO-matrix form a percolation path for fast proton transport. Such a situation was also confirmed by vibration spectra and X-ray diffraction. Although conductivity fell with raising temperature above 100℃, it remained at a level of 10^<-4> Scm^<-1> in the range of 140-160℃. Bulky ligands such as dimethylmalonate tended to suppress conductivity fall at high temperature.