Growth mechanism, structural regulation and energy-oriented functionalization of carbon-based nanotubes

摘要

In the past decades, great progress has been achieved in the studies on synthesis, properties and applications of carbon nanotubes (CNTs), yet little progress especially the direct experimental evidence has been obtained about the growth mechanism. The understanding on the growth mechanism of CNTs is a long-standing and controversial issue and has become a choke point for the further development of CNTs-related fields. By using the in situ thermal analysis-mass spectroscopic technique, the CVD growth process of CNTs with benzene precursor has been clearly illuminated and the six-membered-ring-based growth mechanism through surface diffusion is deduced (Figure 1). [1] Moreover, by applying this mechanism to the synthesis with pyridine precursor, nitrogen-doped CNTs (NCNTs) with predominant pyridinic N over graphitic N have been obtained. [2] And such NCNTs have homogenous distribution of the nitrogen species which is beneficial for the surface functionalization. [3–5] Accordingly, a series of alloyed Pt-TM (TM=Ru, Co, Ni etc) nanoparticles have been directly immobilized onto the outer surface of the NCNTs without pre-modification due to the nitrogen participation. The Pt-TM nanoparticles in so-constructed binary Pt-TM/NCNTs catalysts own high dispersion, narrow size distribution and tunable chemical composition. With these specifications such nanocomposite catalysts have potential applications in fuel cells as demonstrated in the superior electrocatalytic performance for methanol oxidation and oxygen reduction reaction. [4–8]