(Digital Presentation) Highly Efficient and Selective CO2 Electroreduction to CO on Novel Metal-Nitrogen-Carbon (M-N-C) Catalyst

Abstract

The electrocatalytic reduction of CO2 (CO2RR) to CO is an important component of emerging Carbon Capture and Utilization (CCU) technologies. This process often relies on expensive and rare metals such as silver and gold-based materials for high selectivity and conversion rate to CO1,2. It is desired to move away from these metals towards earth-abundant solid materials (e.g., carbon-based) which may serve as heterogeneous electrocatalysts for CO2RR. Herein, a series of novel carbon-based materials with exceptional selectivity/activity for the targeted production of CO is presented. This new class of hybrid catalyst materials have high CO2RR activity which is comparable to the state of the art atomically dispersed Metal-N-C synthesized by the sacrificial support method (SSM). The advantage of this new class of catalysts is that the use of harsh solvents such as nitric acid and potassium hydroxide which are usually required to remove the silica precursor is completely avoided. Not only does this make the immediate process more environmentally friendly, but it also significantly shortens the catalyst synthesis time which increases its industrial viability. The structure and activity of a series of catalysts with different metallic dopants (Fe, Co, Ni, Mn) are investigated. Using this new synthesis technique, a faradaic efficiency for CO formation (FEco) of 96.5 % at -0.3 V vs. RHE is achieved. FEco remains greater than 75 % over the potential range studied from -0.3 V to -1.1 V vs. RHE. By comparison, Fe-N-C by SSM method reaches a maximum FEco of 94.4 % at -0.7 V vs. RHE and FEco remains greater than 85 % over the same potential range.