Copper is the best candidate as metallic electrocatalyst to target commercially valuable hydrocarbons in the electrochemical CO2 reduction reaction (CO2RR). Here we present our work on translating its structure-dependent selectivity to proof of concept devices (H-type and gas-fed cells) using colloidally synthesized Cu nanocrystals in the shape of octahedra (111 terminated) and cubes (100 terminated).1-2 In addition to shape-dependence we show size dependence. Among the cubic nanocrystals (Cucub NCs), the 44 nm ones showed the highest selectivity towards ethylene, reaching up to 44%.1 Octahedral nanocrystals (Cuoh NCs) were synthesized with size between 75–310 nm and the smallest one showed the best faradaic efficiency up to 55% for methane.2 We explain both results through a dual facet mechanisms involving the (100)/(110) interface for the Cucub and (111)/(110) interface for the Cuoh. Finally, we discuss our very recent results concerning the catalytic performance of the two NCs at industrially relevant conditions (i.e. at -100 to -300 mA/cm2 in a gas-fed flow electrolyzer).3 Here, we find that the facet-based control on product selectivity remains consistent even in such conditions.

Facet Dependent Reactivity of Copper Nanocrystals for Electrochemical CO2 Reduction to Valuable Products

ACS Fall 2020 Virtual Meeting

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