The electrocatalytic reduction of CO2 offers a sustainable route to the many carbon fuels and feedstocks that society relies on. [fac-Mn(bpy)(CO)3Br] (bpy, 2,2-bipyridine) is one of the most promising and intensely studied CO2 reduction electrocatalysts. However, the catalytic mechanism remains experimentally unproven and many key intermediates of the prototypical catalyst have not been observed. Here we report the use of vibrational sum-frequency generation spectroscopy to study the catalytic intermediates during CO2 reduction in situ at the electrode surface. We explore the complex applied-potential and acid-dependent mechanistic pathways and provide evidence of the theoretically derived mechanisms. Demonstrating the ability to detect the key species that are only transiently present at the electrode surface is important as the need for an improved mechanistic understanding is a common theme throughout the field of molecular electrocatalysis.
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Raw data for all figures within the paper are freely available from the University of Liverpool Research Data Catalogue at https://doi.org/10.17638/datacat.liverpool.ac.uk/533.
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We are grateful to C. Smith (University of Liverpool) for the synthesis of 1. This work was carried out at the Ultra facility of the UK Central Laser Facility during experiments 15130005, 16130016 and 16230052. A.J.C. and G.N. acknowledge support from EPSRC (EP/K006851/1, EP/P034497/1 and EP/N010531/). G.T. acknowledges support from EPSRC (EP/I004483/1, EP/K013610/1, EP/P022189/1 and EP/P022189/1). This work made use of the ARCHER (via the UKCP Consortium, EPSRC UK EP/K013610/1 and EP/P022189/1) and UK Materials and Molecular Modelling Hub (EPSRC UK EP/P020194/1) High-Performance Computing facilities.
The authors declare no competing interests
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Neri, G., Walsh, J.J., Teobaldi, G. et al. Detection of catalytic intermediates at an electrode surface during carbon dioxide reduction by an earth-abundant catalyst. Nat Catal 1, 952–959 (2018). https://doi.org/10.1038/s41929-018-0169-3