Catalytic properties of cyclo-carbon clusters: An investigation on o[formula omitted] activation and CO oxidation

Abstract

The carbon allotrope-based catalysts attracted considerable attention for oxidation–reduction reactions due to their low-cost and environmentally friendly properties. Systematic investigations are required to explore the catalytic properties and corresponding mechanisms of the new discovered carbon allotropes such as cyclocarbon clusters (cyclo-Cn). Here, using first-principles calculations, we study the stability and electronic properties of cycloCn. Regarding the spin multiplicity and geometry of cycloCn the electronic properties of n-odd and n-even cycloCn were found to be significantly different. Also, based on the EleyRideal (ER) and LangmuirHinshelwood (LH) mechanisms, we focus on the CO oxidation over sp-hybridized molecular carbon allotropes (cyclo-Cn) including recently synthesized cycloC18 by Kaiser, K. et al. (Science2019 365(6459), 1299–1301). In particular, thirteen cycloCn (with n=12-24) are studied. It was found that these carbon clusters may be useful for CO oxidation. We also elucidate the effects of NaCl(100) substrate on the catalytic performance of two cycloCn (n=17, 18) where we found that their optimized structures and the corresponding energy barriers are not very different than that of isolated molecular allotropes. The results show that cycloCn clusters may be a metal-free catalyst for CO oxidation. However, the stability of the cycloCn is a major concern under the acidic or basic conditions required for oxygen electrocatalysis that other groups must consider for further in situ calculations and characterizations.