The Curvature Effect of Pyridinic N Site for Electro Catalyzing Co2 Conversion to Co

Abstract

Carbon material is considered as the promising electrocatalyst for CO2 reduction reaction (CO2RR), especially N-doped carbon material which shows high CO Faradic efficiency (FECO) using pyridinic N species as the active sites. However, in the past decade, more efforts are focused on the preparation of various carbon nanostructure containing abundant pyridinic N specie and few researches study the further modulation of pyridinic-N sites. The curvature of carbon substrate is an easily controllable parameter for modulating the local electronic environment of catalytic sites. In this research, carbon nanotubes (CNTs) with different diameters are applied to modulate the electronic environment of pyridinic N by the curvature effect. The pyridinic N sites doped on CNTs with the average curvature of 0.04 show almost 100% FECO at the current density of 3 mA cm-2 at -0.6 V vs RHE, 91% FECO retention after 12 testing, superior to most of carbon-based electrocatalysts. As demonstrated by density functional theory simulation, the pyridinic N site forms strong local electric field around nearby C active site and protrudes out of the curved CNTs surface like a tip, which remarkably enriches protons around the adsorbed CO2 molecule.

Keywords: carbon nanotubes, curvature effect, pyridinic N, CO2 reduction, CO selectivity