Homogeneous Deposition of Platinum Nanoparticles on Carbon Black for Proton Exchange Membrane Fuel Cell
Homogeneous Deposition of Platinum Nanoparticles on Carbon Black for Proton Exchange Membrane Fuel Cell
复制标题
DOI：
10.1021/ja905749e
复制
发表时间：
2009-10-28
影响因子：
15
通讯作者：
Yu, Jong-Sung
中科院分区：
文献类型：
--
作者：
Fang, Baizeng;Chaudhari, Nitin K.;Yu, Jong-Sung
开发了一种简单有效的方法来合成碳载Pt纳米颗粒（NPs），该方法通过尿素的原位水解和随后的乙二醇（EG）在多元醇过程中的均匀还原实现pH的逐渐增加来结合Pt络合物物种的均匀沉积（HD），从而控制Pt纳米颗粒的尺寸和分散。随着起始Pt盐水溶液中尿素量的增加，Pt络合物物质的尺寸减小，金属Pt NP的尺寸也减小。Pt物种的尺寸减小可能归因于两个决定性因素：空间收缩效应和静电荷效应。通过电化学比表面积和燃料电池极化性能的测定，证明了HD-EG制备的Pt催化剂具有良好的电催化性能。通过HD-EG策略沉积在Vulcan XC-72（VC）炭黑上的Pt NPs与通过常规硼氢化钠还原或通过微波辅助多元醇方法制备的Pt NPs相比显示出更小的尺寸、更均匀的分散、更高的Pt利用效率和显著改善的燃料电池极化性能。特别重要和显著的是，该HD-EG方法对于合成具有可调NP尺寸和均匀颗粒分散的高Pt负载催化剂是非常有效的。通过HD-EG方法制造的高金属负载量催化剂如Pt（60重量%）/VC优于具有中等至低金属负载量的催化剂（即，40和20重量%），甚至在阴极处0.2 mg Pt cm（-2）的非常低的催化剂负载下，这对于VC负载的Pt催化剂是首次报道的。
A simple and efficient approach has been developed for synthesis of carbon-supported Pt nanoparticles (NPs) that combines homogeneous deposition (HD) of Pt complex species through a gradual increase of pH realized by in situ hydrolysis of urea and subsequent uniform reduction by ethylene glycol (EG) in a polyol process, giving control over the size and dispersion of Pt NPs. With increasing amount of urea in the starting Pt salt aqueous solution, the size of Pt complex species decreases and so does that of the metallic Pt NPs. The decrease in size of the Pt species is likely attributable to two determining factors: the steric contraction effect and the electrostatic charge effect. The excellent electrocatalysis ability of the Pt catalysts produced by HD-EG is demonstrated through the determination of electrochemical surface area and fuel-cell polarization performance. The Pt NPs deposited on Vulcan XC-72 (VC) carbon black by the HD-EG strategy show smaller size with more uniform dispersion, higher Pt utilization efficiency, and considerably improved fuel-cell polarization performance compared with the Pt NPs prepared by conventional sodium borohydride reduction or by a microwave-assisted polyol approach. Particularly important and significant is that this HD-EG method is very efficient for the synthesis of high Pt loading catalysts with tunable NP size and uniform particle dispersion. A high metal loading catalyst such as Pt(60 wt %)/VC fabricated by the HD-EG method outperforms ones with mid-to-low metal loadings (i.e., 40 and 20 wt %), even at a very low catalyst loading of 0.2 mg of Pt cm(-2) at the cathode, which is for the first time reported for the VC-supported Pt catalysts.