title: Theoretical Insight into the Hydrogen Evolution Activity of Open-Ended Carbon Nanotubes.
abstract: Carbon nanotubes (CNTs), while inactive by themselves, are often used as a platform in the search of new catalysts for the hydrogen evolution reaction (HER) by introducing metal nanoparticles or other dopants. Here, we examine the HER activity of pristine open-ended CNTs considering both the effects of chirality and hydrogen coverage using electronic structure calculations. The results indicate that the formation of different 5-ring structures at the end of the CNT introduces surface sites that are highly active toward HER, whereas the activity of traditional 6-ring sites is not greatly altered by tube termination. At fixed hydrogen coverage, the enhanced activity of these sites was attributed to valence orbitals residing close to the highest occupied molecular level facilitating electron transfer to protons.
authors.affiliation: COMP Centre of Excellence in Computational Nanoscience, Department of Chemistry, Aalto University , P.O. Box 16100, FI-00076 Aalto, Finland.
authors.forename: Nico
authors.initials: N
authors.lastname: Holmberg
authors.affiliation: COMP Centre of Excellence in Computational Nanoscience, Department of Chemistry, Aalto University , P.O. Box 16100, FI-00076 Aalto, Finland.
authors.forename: Kari
authors.initials: K
authors.lastname: Laasonen
keywords: density functional theory; electrocatalysis; hydrogen evolution reaction; nudged elastic band method; proton-coupled electron transfer; ring size effect