Computational Screening of Single Non-Noble Transition-Metal Atoms Confined Inside Boron Nitride Nanotubes for CO Oxidation

Abstract

Based on density functional theory calculations, the stability and catalytic activity of a series of single non-noble transition-metal (TM) atoms confined on the interior surface of boron nitride nanotubes (BNNTs) with nitrogen vacancy for CO oxidation have been systematically studied. By searching for the reaction pathways of CO oxidation in the Eley− Rideal (ER) mechanism catalyzed by single TM atoms (TM = Sc, Ti, V, Cr, Mn, Fe, Co, Cu, Zn) confined inside BNNT(6,6), we found that Cu−BNNT(6,6) and Mn−BNNT(6,6) are good candidates as highly efficient catalysts, with the energy barriers of the rate-determining step for CO oxidation being 0.24 and 0.37 eV, respectively. Compared with ER reactions, CO oxidation proceeds via the Langmuir−Hinshelwood mechanism with relatively larger energy barriers. We confirmed that the interior surface of BNNT(6,6) provides a better confinement environment than the exterior surface for developing single-atom catalysts. With the appropriate energy barriers, Cu−BNNT(6,6) and Mn−BNNT(6,6) show the satisfactory catalytic performance for CO oxidation.

Theoretical Understandings of Graphene-based Metal Single-Atom Catalysts: Stability and Catalytic Performance

“…Lastly, SACs with graphene-like supports, such as carbon nanotubes, − C 3 N 4 , − BN, − porphyrin/phthalocyanine, ,,,, metal–organic framework (MOF), and zeolitic imidazolate framework (ZIF) generated materials, ,− also demonstrate high catalytic performance on many reactions. Their local coordination environments are more or less similar to the graphene-anchored SAs reviewed in this work.…”

Hierarchical Porous Carbon Nitride-Crumpled Nanosheet-Embedded Copper Single Atoms: An Efficient Catalyst for Carbon Monoxide Oxidation

“…However, most of the discussed previous reports have focused on using Cu or Cu-oxide nanoparticles without much emphasis on the atomic doping effect or single atoms. , Ubiquitously, the exposed atoms on the surface of Cu nanoparticles serve as active catalytic sites; meanwhile, the inner atoms are spectators, which devalue the catalytic activity. Likewise, the ease of oxidation feasibility of Cu nanoparticles [i.e., Cu(0) to Cu (I) or Cu­(II)] in oxygen-rich atmospheres remains a daunting challenge that precluding commercial utilization of Cu-based catalysts for CO Ox . ,, Distinct from Cu nanoparticles, decreasing the size of Cu particle to the single atom can maximize the atomic efficiency, enhance the dispersion, enlarge the surface area, and provide massive interior/exterior active sites, driven by the quantum size effect and alteration of the electronic structure of Cu. − However, stabilization of Cu single atoms is a major challenge, owing to the great surface free energy at the single-atom scale. This could be defeated by anchoring Cu single atom on a metal oxide support or alloying with another metal. − Notably, the Cu-based single-atom catalyst for CO Ox has received meager attention as most previous reports have centered around computational studies without enough emphasis on the experimental performance. − For instance, the Cu­(I) single-atom/TiO 2 –C achieved 90% CO conversion at (103 °C), which was superior to Cu­(I)/TiO 2 by 1.82 times (90% at 188 °C) and Cu­(I) by 2.91 times (90% at 300 °C) in addition to higher stability .…”