Boosting Electrocatalytic Performances of Palladium Nanoparticles by Coupling with Metallic Single-Walled Carbon Nanotubes

Noble metal catalysts are core materials for many energy conversion and storage technologies such as fuel cell and hydrogen storage, while the performances of the noble metals depend critically on the nature of support materials. Herein, for the first time, we report the use of sorted high-purity metallic (m-) and semiconducting (s-) single-walled carbon nanotubes (SWNTs) as support materials for a typical noble metal catalyst, Pd, which has been believed to have strong interactions with SWNTs. Our results clearly suggest that electrocatalytic performances of the noble metals/SWNTs hybrid system, specifically in hydrogen electrosorption and formic acid electrooxidation, exhibit strongly sensitive dependence with respect to the electronic type of SWNT supports. Pd nanoparticles on m-SWNTs demonstrate much enhanced electrocatalytic activities compared with those on s-SWNTs or unsorted-SWNTs. Our in-depth mechanism studies indicate that the m-SWNTs in the nanocomposite tend to provide more effective charge-transfer interfaces with Pd nanoparticles, more likely leading to higher electron densities on Pd nanoparticles to boost their catalytic performance. The present study provides a novel window onto the design and synthesis of new feasible electrocatalyst system for efficient energy conversion and storage.