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The renewable electroreduction of CO 2 to CO is a key component of future clean energy scenarios. These scenarios allow for the recycling of carbon emissions into value-added chemicals which achieves the joint goal of reducing greenhouse gase(s) while producing valuable chemical product(s). A catalyst which has a high activity and selectivity for the electroreduction of CO 2 to CO is highly desired for these applications. Nonprecious metal catalysts (non-PGM) and specifically metal− nitrogen−carbon (M−N−C) catalysts are prime cathode candidates as they are selective for CO and H 2 formation with only trace amounts of other products such as CH 4 . The traditional method of production of atomically dispersed M−N−C proceeds either through a sacrificial poymer approach or through hard-templating the catalyst with silica. The other is through the direct pyrolysis of nonabundant metal macrocycles such as MOF-based precursors via a soft-templating approach. These syntheses have substantial industrial limitations as they require harsh acid or basic solvents for postpyrolytic removal of the support or they require rare chemical precursors. The method herein uses mechanochemical mixing of a fluorine-containing polymer with common pyrolytic precursors for the in situ removal of the template during the first pyrolysis. Further ball-milling and post-treatment in ammonia atmosphere yield a highly selective catalyst for CO 2 reduction. The role of the metal center in these M−N−C catalysts in promoting CO 2 reduction is explored (M = Fe, Ni, Co, Mn) vs the performance of metalfree N−C. A mechanistic pathway for CO 2 reduction on the various M−N−C catalysts is suggested. The champion catalyst in terms of overall selectivity/activity (Ni−N−C) boasts a 98.9 ± 0.2% faradaic efficiency for CO formation (FE co ) at −1.1 V vs RHE and an unmatched selectivity for CO 2 reduction (FE co > 85%) even at low overpotential (E = −0.3 V vs RHE) compared to traditional Ni− N−C. The catalysts synthesized here present a promising class of electrocatalysts which may be explored for a range of electrocatalytic applications.

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. References 1. Varela, A. S., Ranjbar Sahraie, N., Steinberg, J., Ju, W., Oh, H.-S., & Strasser, P. (2015). Metal-Doped Nitrogenated Carbon as an Efficient Catalyst for Direct CO2 Electroreduction to CO and Hydrocarbons. In Angewandte Chemie International Edition. 2. Nguyen, D. L. T., Kim, Y., Hwang, Y. J., & Won, D. H. (2019). Progress in development of electrocatalyst for CO 2 conversion to selective CO production. In Carbon Energy. Figure 1