Revealing the Origin of Activity in Nitrogen‐Doped Nanocarbons towards Electrocatalytic Reduction of Carbon Dioxide

Abstract

Carbon nanotubes (CNTs) are functionalized with nitrogen atoms for reduction of carbon dioxide (CO2 ). The investigation explores the origin of the catalyst's activity and the role of nitrogen chemical states therein. The catalysts show excellent performances, with about 90 % current efficiency for CO formation and stability over 60 hours. The Tafel analyses and density functional theory calculations suggest that the reduction of CO2 proceeds through an initial rate-determining transfer of one electron to CO2 , which leads to the formation of carbon dioxide radical anion (CO2 (.-) ). The initial reduction barrier is too high on pristine CNTs, resulting in a very high overpotentials at which the hydrogen evolution reaction dominates over CO2 reduction. The doped nitrogen atoms stabilize the radical anion, thereby lowering the initial reduction barrier and improving the intrinsic activity. The most efficient nitrogen chemical state for this reaction is quaternary nitrogen, followed by pyridinic and pyrrolic nitrogen.

Highly Efficient Porous Carbon Electrocatalyst with Controllable N‐Species Content for Selective CO2 Reduction

“…In addition, the capacity to suppress the competing H 2 evolution reaction makes the N‐doped carbon materials much more appealing for selective CO 2 conversion . Up to now, various kinds of N‐doped carbon nanostructures, such as N‐doped carbon fibers, carbon nanotubes, nanodiamond, and graphene have been explored for CO 2 RR . However, the low productivity and selectivity remain the major challenges yet to be tackled.…”

Carbon-Based Metal-Free Electrocatalysis for Energy Conversion, Energy Storage, and Environmental Protection

“…11, metal-free carbon catalysts based on N-doped carbon nanofibers (NCNFs) generated from the electrospinning of polyacrylonitrile (PAN) was first reported in 2013 for CO 2 RR [36]. Subsequently, N-doped CNTs (NCNTs) were demonstrated to be highly active, selective, and stable catalysts for the electrocatalytic reduction of CO 2 to CO [37][38][39][40]. Combined XPS analyses and DFT calculations indicate that pyridinic N plays an important role in CO 2 RR, whereas for graphitic N, electrons are localized in the π antibonding orbital, becoming less accessible for CO 2 binding.…”

“…Because ORR, OER, and HER have been reviewed in several previously published articles [4,[10][11][12], the focus in this review will be on recent advances and new reactions (e.g., CO 2 RR, multifunctional electrocatalysis). A critical overview of efficient methods for developing carbon-based metal-free catalysts for various energy conversion/storage and environmental protection devices, including ORR in fuel cells [13][14][15][16][17], ORR and OER in metal-air batteries [18][19][20][21][22][23][24][25][26][27][28], OER and HER in water-splitting units [29][30][31], I − /I 3− reduction in dye-sensitized solar cells [32][33][34][35], and CO 2 RR in Li-CO 2 batteries [36][37][38][39][40][41][42] will then be provided. Finally, perspectives and challenges in this fast-growing and significant field are outlined.…”

Recent Progress in the Theoretical Investigation of Electrocatalytic Reduction of CO2

“…Nitrogen-doped graphene has been experimentally demonstrated to be the electrocatalyst for CO 2 reduction to CO and HCOOH, [141,142] supported by DFT calculation. Liu et al illustrated that the N-dopant changed the electronic properties of pristine graphene and formed N-C covalent bond, resulting in the decreased energy barrier to key intermediate, *COOH, weakened E CO and strengthened E COOH .…”