Difference in the cooperative interaction between carbon nanotubes and Ru particles loaded on their internal/external surface

Abstract

This paper examines differences in the cooperative interaction between carbon nanotubes (CNTs) and Ru particles loaded on their internal/external surface. The techniques used were transmission electron microscopy, X-ray photoelectron spectroscopy, CO chemisorption, X-ray diffraction, N₂ physisorption, hydrogen temperature-programmed reduction and two probe catalysis reactions, namely ammonia decomposition and preferential oxidation of CO in H₂-rich atmosphere (PROX). The results show that the loading of highly dispersed Ru particles on CNTs does not change the structure of the CNTs. The cooperative interaction between Ru particles and associated CNT surfaces is dependent on the position of Ru particles and the surface functional groups of CNTs. Due to the electron-deficient structure of Ru particles confined inside CNT channels, they have an inferior ammonia decomposition activity to those deposited on the CNT external surface. For PROX, the catalytic performance of Ru particles confined inside CNT channels is superior compared to that over Ru particles deposited outside CNTs, which we attribute to the selective reactant enrichment of CO over H₂ inside the CNTs.