Spotlights on Recent JACS Publications

Abstract

In 2007, reseachers at China’s Dalian Institute of Chemical Physics reported that the catalytic activity of iron oxidenanoparticles could be tuned by encapsulating them in carbon nanotubes (CNTs) (DOI: 10.1021/ja0713072). Subsequently, researchers led by Xulian Pan and Xinhe Bao at Dalian, as well as other groups, reported a series of experimental studies showing that the catalytic activity for a number of transition metal catalysts can be enhanced or reduced by encapsulating them inside CNTs. Now those researchers and their co-workers study the underlying mechanisms that would explain the effect of CNTs on their catalytic activity (DOI: 10.1021/ja511498s). They combine density functional theory with the experimental results that have been reported for several CNT-encapsulated transition metal catalysts. They find that the nanospace and π electronshighly mobile electrons present in the curved graphene sheets that make up nanotubesaffect the dissociative binding energy of several probe molecules. It is decreased on the encapsulated particles with respect to those outside of the nanotube. For encapsulated iron, the weakened binding results in an increased catalytic activity in CO hydrogenation, while for ruthenium the confinement results in the opposite effect in CO hydrogenation and NH3 decomposition. Nanotubes and the confinement effects may be used to modulate important catalytic processes. Alexander Hellemans