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).