Facet-Dependent Selectivity of Cu Catalysts in Electrochemical CO₂ Reduction at Commercially Viable Current Densities

Abstract

Despite substantial progress in the electrochemical conversion of CO 2 into value-added chemicals, the translation of fundamental studies into commercially relevant conditions requires additional efforts. Here, we study the catalytic properties of tailored Cu nanocatalysts under commercially relevant current densities in a gas-fed flow cell. We demonstrate that their facet-dependent selectivity is retained in this device configuration with the advantage of further suppressing hydrogen production and increasing the faradaic efficiencies toward the CO 2 reduction products compared to a conventional H-cell. The combined catalyst and system effects result in stateof-the art product selectivity at high current densities (in the range 100−300 mA/cm 2 ) and at relatively low applied potential (as low as −0.65 V vs RHE). Cu cubes reach an ethylene selectivity of up to 57% with a corresponding mass activity of 700 mA/mg, and Cu octahedra reach a methane selectivity of up to 51% with a corresponding mass activity of 1.45 A/mg in 1 M KOH.

High carbonate ion conductance of a robust PiperION membrane allows industrial current density and conversion in a zero-gap carbon dioxide electrolyzer cell

“…Remarkable progress was observed in the partial current densities for product formation, most importantly for carbon monoxide (CO), 7 ethylene 8,9 and methane. 10,11 While it seemed particularly challenging to reach 100-200 mA cm À2 current density a few years ago, operation at 1 A cm À2 partial current density for different products might be an achievable target in the near future.…”

Metal–ligand bond strength determines the fate of organic ligands on the catalyst surface during the electrochemical CO2 reduction reaction

“…17,19,22 Furthermore, colloidal suspensions of these catalysts are appealing as they can be used to deposit CuNCs onto a variety of supports, including gas-diffusion electrodes that can operate at commercially-relevant current densities. 23,24 In some of these studies, the organic ligands functionalising the surface of the NC catalysts were removed prior to catalytic testing using plasma, mild solvent-washing or hydrazine treatments. 17,22,25 However, extreme care is needed to ensure that no undesirable modications of the catalysts are caused by these ligand removal treatments, such as changes of exposed facets or of the copper oxidation state as well as deposition of poorlyunderstood carbonaceous material on the surface.…”

Shaping non-noble metal nanocrystals via colloidal chemistry

“…5c). 70,[86][87][88] Size, in addition to shape, has been found to play an unpredicted yet crucial role. Indeed, while the shape governs the facets exposed on the surface, the size regulates the area ratio between these facets.…”