(558t) Engineering Geometric and Defective Nanostructures of Carbon Materials for Selective Carbon Dioxide Electro-Reduction

Electrocatalytic reduction of CO₂ into value added chemicals or fuels is a promising technique towards a carbon-neutral chemical process. The electrochemical reduction of CO₂ is a complicated process involving multiple protons coupled electron transfer, theoretically resulting in a variety of products (e.g. CO, HCOOH, CH₄, C₂H₄ and C₂H₅OH). Therefore, the major challenge in CO₂ reduction lies in the manipulation of the selectivity towards a specific product as demanded. However, the study on CO₂ reduction has not substantially advanced primarily because of the lack of fundamental understanding of the reaction mechanism and the challenge of discovering efficient and robust catalysts for the various multi-electron transfer processes. Researchers have screened a wide range of metal-based materials for electrochemical reduction of CO₂, and found only copper-based metals exhibit selectivity towards formation of hydrocarbons and oxygenates at fairly high efficiencies while most others favor production of carbon monoxide or formate. Beyond Cu, we have recently shown metal free N-doped graphene quantum dots (NGQDs) can yield C_≥2 products. When enriching the N-doping at the edge of carbon nanostructures, the NGQDs exhibit exceptional activity towards formation of C₂H₄ and C₂H₅OH with a combined Faradaic efficiency of 40% and a partial current density of 100 mA cm^-2 at a low overpotential.

Here we will present how the carbon geometric and defective nanostructure can be further engineered to tune the catalytic activity and selectivity towards CO₂ reduction with an emphasis on the production of hydrocarbons and oxygenates products. We will discuss the key structural and electronic factors that govern the selectivity of carbon catalysts towards production of CO, CH₄ and C₂ products (e.g. C₂H₄ and C₂H₅OH). This study provides in-depth insights into developing high-performance carbon-based catalysts for electrochemical reduction of CO₂.