Enhancing the reactivity of CO2 conversion to hydrocarbons by modulating the electron properties of carbon nanotube based single atom catalysts with curvature effect

Abstract

The CO2 electroreduction is always impeded by the low activity and selectivity on single atom catalysts (SAC). The regulation of the curvature of the substrate is a promising strategy to address these issues. Herein, we have chosen carbon nanotubes (CNTs) as the substrates for SACs. Perfect scaling lines can be plotted between adsorption energies of *CO and *COOH on armchaired systems, indicating that the d-band theory is still established on SACs based on armchared CNTs. The origin of this character can be attributed to the similar d-band width of TM atoms in TM@CNTs. The curvature effect can modulate the slopes of the fitted lines increased from ∼1.18 to ∼1.41 with increasing curvatures. However, the fitted lines on zigzag systems are bad due to some deviated candidates, like Cu, V, and Cr systems. We eventually selected Co@4-4CNT, Co@5-5CNT, Mn@4-4CNT and Mn@5-5CNT as the promising candidates for CRR based on following characters: similar Ead[*CO] as bulk Cu and lower hydrogen evolution reactivity. The Co@CNTs (Mn@CNTs) prefer to produce CH3OH (CO and CH4) compared to Mn@CNTs (Co@CNTs). In addition, HCOOH can be produced at relatively lower limiting potentials (−0.58∼-0.65 V) than hydrocarbons (−0.61∼-0.76 V).