CO2 Electroreduction on Mono- and Bi-Metallic M-N-C Catalysts

Abstract

The production of syngas by traditional processes such as steam methane reforming is energetically expensive and leads to substantial CO2 emissions. This strongly motivates the development of CO2 electroreduction at ambient conditions. As a family of non-precious metal catalysts, transition metal-nitrogen-carbon electrocatalysts are cost effective and highly selective towards syngas production1,2. In this presentation, we will show our current research into mono and bi-metallic nitrogen-doped carbon (M-N-C, M = Fe, Mo or FeMo) electrocatalysts for syngas production. The electrocatalyst composition (i.e. the Fe:Mo ratio in the bimetallic electrocatalyst) was tuned, in combination with the potential applied, to control the selectivity and therefore the electrocatalyst’ ability to generate syngas. We show that a higher ratio of iron to molybdenum leads to an increase in selectivity to CO over H2 production. We show a greatly improved production rate for CO using traditional Fe-N-C which maxes out at a CO partial current density higher than that of commercial Ag nanoparticles (jco= -30.9 mA/cm2 geo at -1.1 VRHE) using a custom-built flow cell. The difficulties and importance of considering intrinsic catalytic activity is stressed to compare electrocatalytic activity. Apart from catalyst composition, reaction conditions can also substantially alter the electrochemical CO2/H2O co-electrolysis3. The catalyst composition can be used as an engineering control for the desired product selectivity by using a variable precursor metallic ratio in bi-metallic M-N-C catalysts. Potential control may be used alongside variations in reaction conditions for the dynamic control over the selectivity to syngas. Reference Delafontaine, L., Asset, T., & Atanassov, P. (2020). Metal–Nitrogen–Carbon Electrocatalysts for CO 2 Reduction towards Syngas Generation. ChemSusChem, 13(7), 1688–1698. 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 CO2Electroreduction to CO and Hydrocarbons. Angewandte Chemie, 127(37), 10908–10912. Pan, F., & Yang, Y. (2020). Designing CO2 reduction electrode materials by morphology and interface engineering. Energy & Environmental Science, 13(8), 2275–2309. Figure 1