(Keynote) Mechanisms and Selectivity of the Electrochemical CO2 Reduction Reaction on Multiple-Site Versus Single-Site Catalysts

Monday, 2 October 2017: 13:50
National Harbor 8 (Gaylord National Resort and Convention Center)
P. Strasser (Technical University Berlin)
Strategies toward closing the anthropogenic carbon cycle using the chemical conversion of CO2 in off-gas streams of steel-mills or cement-plants into useful molecules have become a scientific and technological priority. Of all chemical ways to convert CO2 into hydrocarbons, the direct electrochemical coupling of water electrolysis and CO2 reduction appears attractive, as it is a one-pot process step, occurs at ambient temperature and pressures, involves solely water and CO2 as reactants, and may involve renewable electricity from wind, solar or hydro power plants.

The CO2 electroreduction to gaseous C1 products such as CO or CH4 is often carried out on the surface of metal catalysts such as Cu, Ag or Au. At industrially relevant current densities and electrode potentials, however, these catalysts typically suffer from low faradaic C1 product selectivities due to the competing, very fast reduction of water, i.e. the hydrogen evolution reaction. New catalyst concepts with tunable selectivity for hydrogen evolution versus CO2 reduction are needed(1-3).

In this contribution, we share recent experimental and computational mechanistic studies(4) on the electroreduction of CO2, CO, HCOH on metallic multi-site versus metal/heteroatom-doped carbon single-site catalysts. We provide new insight into CO selectivity trends and put particular emphasis on the competing reaction pathways to methane and methanol. We show that carbon-based single site catalysts are an intriguing cost-effective alternative to metals.

1. H. Mistry, A. S. Varela, S. Kühl, P. Strasser, B. R. Cuenya, Nanostructured electrocatalysts with tunable activity and selectivity. Nature Reviews Materials, 16009 (2016).

2. H. Mistry et al., Highly selective plasma-activated copper catalysts for carbon dioxide reduction to ethylene. Nat Commun, (2016).

3. A. S. Varela et al., Metal-Doped Nitrogenated Carbon as an Efficient Catalyst for Direct CO2 Electroreduction to CO and Hydrocarbons. Angewandte Chemie International Edition 54, 10758-10762 (2015).

4. A. Bagger, W. Ju, A. S. Varela, P. Strasser, J. Rossmeisl, Single site porphyrine-like structures advantages over metals forselective electrochemical CO2reduction. Catal Today, http://dx.doi.org/10.1016/j.cattod.2017.1002.1028 (2017).