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通过两步还原法制备了Pd/Ni双金属催化剂.由于金属Pd原子在先行还原的Ni纳米粒子表面的外延生长以及其在Ni表面及Pd表面生长表现出的吉布斯自由能差异,最终导致了异结构Pd/Ni纳米粒子的形成.高分辨电子透射显微镜结果证实了异结构的存在,然而X射线衍射测量表明Pd/Ni纳米粒子具有类似于Pd的面心立方结构.制备的Pd/Ni纳米粒子与同等条件下合成的Pd纳米粒子相比对甲酸氧化呈现了更高的电催化活性,而且电催化稳定性也要明显优于纯Pd纳米粒子,证明Pd/Ni双金属催化剂是可选的直接甲酸燃料电池阳极催化剂.双金属催化剂对甲酸氧化电催化活性和稳定性增强可能是Ni原子的修饰改变了Pd粒子表面配位不饱和原子的电子结构所致. 相似文献
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Metal-Element-Incorporation Induced Superconducting Hydrogen Clathrate Structure at High Pressure
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The recent observation of high critical temperature Tc in lanthanum and Yttrium hydrides confirms the key role of hydrogen cage(H-cage)in determining high superconductivity.Here,we present a new class of metastable H12 clathrate structures based on the icosahedral cI 24-Na that can be stabilized by incorporation of metal elements.Analysis shows that the charge transfer from metal atoms to H atoms contributes to forming the H12 clathrate.Nine dynamically stable structures are identified to exhibit superconductivity,and a maximum Tc of 28K is found in voids-doped Mo6H24.Calculations reveal that the low Tc is attributed to the weak interaction between H atoms in each cage due to the long H–H distance.The current results provide a possible route to design H-cage containing superconductors. 相似文献
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