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O: Fachverband Oberflächenphysik
O 98: Graphene I: Growth, Structure and Substrate Interaction (joint session O/TT)
O 98.1: Vortrag
Donnerstag, 19. März 2020, 10:30–10:45, GER 37
Design principles for doping graphene for electrochemical CO2 reduction: Insights from Theory — •Sudarshan Vijay1, Joseph Gauthier2, Hendrik Heenen1, Vanessa Bukas1, Henrik Kristoffersen1, and Karen Chan1 — 1CatTheory, Department of Physics, Technical University of Denmark — 2SUNCAT Center for Interface Science and Catalysis, Department of Chemical Engineering
Graphene based 2D catalysts hold great promise for CO2 reduction to CO and CH4. Recent experimental investigations [1,2] show metal doped Iron-Nitrogen-Carbon (Fe-N-C) catalysts are able to reduce CO2 to CO at low overpotentials and with high selectivity. However, modelling these materials in an electrochemical environment poses several open challenges. In this work, we present a theoretical investigation on Fe-N-C catalysts which includes the effect of potential, interfacial pH, change in local spin states to properly elucidate the mechanism for CO2 reduction. We find that the electronic structure of Fe-N-C resembles graphene more than it does a metal, with significantly fewer states at the fermi level. Charge dependence of binding energies of key intermediates depend on the position of the highest energy d-orbital with respect to the fermi level. Using computed reaction energetics coupled with mean-field kinetic models, we are able to ascertain the mechanism for CO2 reduction and compare our results with experimental findings. We extend this analysis to other 2D material systems and propose rational design principles.
[1] Science 14 Jun 2019: Vol. 364, Issue 6445, pp. 1091-1094 [2] ACS Energy Lett. 2018, 3, 4, 812-817