Babu Panakkattu K, Chung Jong Ho, Kuk Seung Taek, Kobayashi Takeshi, Oldfield Eric, Wieckowski Andrzej
J Phys Chem B. 2005 Feb 24;109(7):2474-7. doi: 10.1021/jp040729k.
We report the first observation of the 13C nuclear magnetic resonance spectroscopy (NMR) of 13CO, adsorbed from 13CO saturated 0.5 M sulfuric acid solutions, onto the surfaces of commercial Ru-black nanoparticles. The 13C NMR spectra consist of a symmetrically broadened peak having a large isotropic shift as compared to CO adsorbed onto supported Ru catalysts. The variation of the spin-lattice relaxation rate follows Korringa behavior, indicating the metallic nature of adsorbed CO, in addition to varying across the spectrum in a Korringa-like manner. Motional narrowing of the NMR spectrum at higher temperatures, together with an additional contribution to the spin-lattice relaxation rate, indicate that adsorbed CO undergoes rapid diffusion on the particle surfaces. A two-band model analysis of the NMR results indicates that the CO adsorption bond is weaker on Ru as compared to either Pt or Pd. This is also supported by a reduction in the activation energy for CO diffusion on Ru vs either Pt or Pd nanoparticles.
我们报告了首次观察到从13CO饱和的0.5M硫酸溶液中吸附到商用钌黑纳米颗粒表面的13CO的13C核磁共振光谱（NMR）。与吸附在负载型钌催化剂上的CO相比，13C NMR光谱由一个具有大各向同性位移的对称展宽峰组成。自旋晶格弛豫率的变化遵循科林加行为，表明吸附的CO具有金属性质，此外还以类似科林加的方式在整个光谱中变化。在较高温度下NMR光谱的运动窄化，以及对自旋晶格弛豫率的额外贡献，表明吸附的CO在颗粒表面经历快速扩散。对NMR结果的双带模型分析表明，与Pt或Pd相比，CO在Ru上的吸附键较弱。这也得到了CO在Ru上相对于Pt或Pd纳米颗粒扩散的活化能降低的支持。
