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通过乙二醇还原,在VulcanXC-72炭黑上负载了三种具有不同平均粒径(1.7nm,3.0nm和5.0nm)的Pt催化剂。利用透射电子显微镜,研究了载体炭黑表面的微孔与Pt催化剂之间的几何相互作用。结果表明:尺寸较小的Pt颗粒(平均粒径为1.7nm)通常被包含在载体表面的微孔中,表现为被一薄碳层所覆盖并嵌入炭黑基体。而尺寸较大的Pt颗粒(平均粒径为3.0nm和5.0nm)则不存在这种现象,往往显示出裸露的清洁表面。这种与载体表面微孔的不同相互作用引起了Pt颗粒在电化学活性比表面上的反常尺寸效应,进而影响了其催化甲醇氧化的质量比活性。
On Vulcan XC-72 carbon black, three Pt catalysts with different average particle sizes (1.7 nm, 3.0 nm and 5.0 nm) were supported by ethylene glycol reduction. Transmission electron microscopy was used to study the geometrical interaction between Pt on the surface of carrier carbon black and Pt catalyst. The results show that the smaller Pt particles (1.7 nm average particle diameter) are usually contained in the pores of the support surface, which are covered by a thin carbon layer and embedded in the carbon black matrix. The larger Pt particles (average particle size of 3.0 nm and 5.0 nm) do not exist this phenomenon, often showing a bare clean surface. This different interaction with the micropores on the surface of the support causes an anomalous size effect of the Pt particles on the electrochemically active surface, which in turn affects the mass specific activity of the catalyzed methanol oxidation.