University of Waterloo, Department of Chemistry, Waterloo, Ontario, Canada N2L 3G1.
Nat Chem. 2010 Apr;2(4):286-93. doi: 10.1038/nchem.553. Epub 2010 Feb 28.
Shape- and size-controlled supported metal and intermetallic nanocrystallites are of increasing interest because of their catalytic and electrocatalytic properties. In particular, intermetallics PtX (X = Bi, Pb, Pd, Ru) are very attractive because of their high activity as fuel-cell anode catalysts for formic acid or methanol oxidation. These are normally synthesized using high-temperature techniques, but rigorous size control is very challenging. Even low-temperature techniques typically produce nanoparticles with dimensions much greater than the optimum <6 nm required for fuel cell catalysis. Here, we present a simple and robust, chemically controlled process for synthesizing size-controlled noble metal or bimetallic nanocrystallites embedded within the porous structure of ordered mesoporous carbon (OMC). By using surface-modified ordered mesoporous carbon to trap the metal precursors, nanocrystallites are formed with monodisperse sizes as low as 1.5 nm, which can be tuned up to ∼3.5 nm. To the best of our knowledge, 3-nm ordered mesoporous carbon-supported PtBi nanoparticles exhibit the highest mass activity for formic acid oxidation reported to date, and over double that of Pt-Au.
由于其催化和电催化性能，形状和尺寸可控的负载型金属和金属间纳米晶越来越受到关注。特别是，PtX（X=Bi、Pb、Pd、Ru）金属间化合物由于其作为甲酸或甲醇氧化燃料电池阳极催化剂的高活性而非常有吸引力。这些通常使用高温技术合成，但严格的尺寸控制非常具有挑战性。即使低温技术通常也会产生尺寸远大于燃料电池催化所需的最佳<6nm 的纳米颗粒。在这里，我们提出了一种简单而强大的化学控制方法，用于合成负载在有序介孔碳（OMC）多孔结构内的尺寸可控的贵金属或双金属纳米晶。通过使用表面修饰的有序介孔碳来捕获金属前体，可以形成尺寸均一的纳米晶，尺寸低至 1.5nm，最高可达约 3.5nm。据我们所知，3nm 有序介孔碳负载的 PtBi 纳米颗粒在甲酸氧化方面表现出迄今为止报道的最高质量活性，是 Pt-Au 的两倍多。
