甘氨酸燃烧法合成复合氧化物及电化学研究

Synthesis of complex oxides by glycine-nitrate combustion and their electrochemical characteristics

用甘氨酸 硝酸盐燃烧合成法 ,制备镧锶镍复合氧化物的陶瓷粉末。按化学计量比 ,配制甘氨酸与硝酸盐水溶液。将先驱物加热蒸发过量水 ,产生一种粘稠溶液 ,再进一步加热使之自燃并迅速燃烧 ,制得了表面积较大的复合氧化物的陶瓷粉末。通过研究电极制备及测试 ,得到一系列循环伏安曲线。结果表明 :当催化剂与乙炔黑之比为 7∶3时 ,双功能氧电极有最大的催化电流。镍网和La0 .75 Sr0 .2 5 NiO3与乙炔黑组成的电极比镍网和乙炔黑电极有更好的催化活性。并详细讨论了氧还原和氧析出的电化学反应机理。报道了La0 .7Sr0 .3NiO3在充氧和未充氧时的电化学曲线 ,结果表明 :氧电极有双功能催化特性 ,但不是完全可逆。总结了LaxSr1-xNiO3电化学特性 ,当x =0 .1 5、0 .70、0 .75、1时 ,复合氧化物作为氧电极有明显的电催化特性。预测了该复合氧化物的陶瓷粉末在氧还原与氧析出电化学反应时的实际作用。

A new combustion synthesis method, the glycine-nitrate process, has been used to prepare complex oxide ceramic powders of strontium-substituted lanthanum nickel. A precursor was prepared by combining glycine with metal nitrates in their appropriate stoichiometric rations in an aqueous solution. The precursor was heated to evaporate excess water for yielding a viscous liquid, then it was heated further to cause the precursor liquid to autoignite. Combustion was quick and self-sustaining. The ceramic powders of complex oxides with a high specific surface area were prepared. Electrical poles of oxygen were prepared and detected to obtain a series of cyclic voltammetry curves. The results show that the bifunctional oxygen electrode has the most catalytic current when the ratio of catalyst to ethine black is 7∶3 and the pole, which is composed of nickel net and mixture of La 0.75 Sr 0.25 NiO 3 and ethine black, performs better catalytic activity than that is composed of nickel net and ethine black. The electrochemical reaction processes of oxygen reduction and oxygen release were also discussed in detail as well as the curves of La 0.7 Sr 0.3 NiO 3 with and without flowing oxygen were reported. The result shows that oxygen electrode have bifunctional catalyst activity but it is not completely reversible. The electrochemical characteristic parameters of La xSr 1-x NiO 3 were summarized. The complex oxides as oxygen electrode have obviously electrocatalytic activity when x=0.15, 0.70, 0.75 and 1. It has been predicted that the complex oxide ceramic powders are useful for oxygen reduction and oxygen release.