Facile synthesis of palladium phosphide electrocatalysts and their activity for the hydrogen oxidation, hydrogen evolutions, oxygen reduction and formic acid oxidation reactions
Facile synthesis of palladium phosphide electrocatalysts and their activity for the hydrogen oxidation, hydrogen evolutions, oxygen reduction and formic acid oxidation reactions
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DOI：
10.1016/j.cattod.2015.09.031
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发表时间：
2016-03-15
期刊：
影响因子：
5.3
通讯作者：
Sundaram, V. N. Naranammalpuram
中科院分区：
文献类型：
--
作者：
Kucernak, Anthony R. J.;Fahy, K. F.;Sundaram, V. N. Naranammalpuram
我们展示了一种新的方法来生产高度分散的负载型金属磷化物粉末，该粉末具有小粒度，提高稳定性和提高一些有用反应的电催化活性。该方法包括利用非常简单和可扩展的合成工艺，一步将高表面积碳上支撑的金属转化为金属磷化物。我们利用这种方法将市售的Pd/C粉末转化成粒径为4.5-5.5 nm的分散在碳上的PdP2和Pd5P2颗粒。对金属磷化物催化剂进行了氧还原反应、氢氧化析出反应和甲酸氧化反应试验。与未转化的Pd/C材料相比，我们发现在不同水平上合金化P可以将Pd上的氧化物形成转移到更高的电位，从而在循环研究中（5k循环时ECSA保留率增加20%）和空气热处理中具有更高的稳定性。PdP2和Pd5P2颗粒内的氢吸收增强。与迄今为止报道的最活跃的甲酸氧化催化剂（特别是PdP2）相比，磷化物具有优势，并且与单独的Pd相比，表面中毒显著减少。从催化剂表面磷原子的水活化增加的角度来看，所研究反应的机理变化是合理的。其中一种催化剂PdP2/C作为阳极和阴极催化剂在燃料电池中进行了测试，表现出良好的性能。(C) 2015年作者。Elsevier B.V.出版
We demonstrate a new approach for producing highly dispersed supported metal phosphide powders with small particle size, improved stability and increased electrocatalytic activity towards some useful reactions. The approach involves a one-step conversion of metal supported on high surface area carbon to the metal phosphide utilising a very simple and scalable synthetic process. We use this approach to produce PdP2 and Pd5P2 particles dispersed on carbon with a particle size of 4.5-5.5 nm by converting a commercially available Pd/C powder. The metal phosphide catalysts were tested for the oxygen reduction, hydrogen oxidation and evolution, and formic acid oxidation reactions. Compared to the unconverted Pd/C material, we find that alloying the P at different levels shifts oxide formation on the Pd to higher potentials, leading to greater stability during cycling studies (20% more ECSA retained, 5k cycles) and in thermal treatment under air. Hydrogen absorption within the PdP2 and Pd5P2 particles is enhanced. The phosphides compare favourably to the most active catalysts reported to date for formic acid oxidation, especially PdP2, and there is a significant decrease in poisoning of the surface compared to Pd alone. The mechanistic changes in the reactions studied are rationalised in terms of increased water activation on the surface phosphorus atoms of the catalyst. One of the catalysts, PdP2/C is tested in a fuel cell as anode and cathode catalyst and shows good performance. (C) 2015 The Authors. Published by Elsevier B.V.