Valery Okatenko

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Alloying as a Strategy to Boost the Stability of Copper Nanocatalysts during the Electrochemical CO2 Reduction Reaction

Anastasia Blokhina, Raffaella Buonsanti, Anna Loiudice, Valery Okatenko, Kevin Rossi, Dragos-Constantin Stoian

2023

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The coupling of CO-generating molecular catalysts with copper electrodes in tandem schemes is a promising strategy to boost the formation of multi-carbon products in the electrocatalytic reduction of CO2. While the spatial distribution of the two components is important, this aspect remains underexplored for molecular-based tandem systems. Herein, we address this knowledge gap by studying tandem catalysts comprising Co-phthalocyanine (CoPc) and Cu nanocubes (Cu-cub). In particular, we identify the importance of the relative spatial distribution of the two components on the performance of the tandem catalyst by preparing CoPc-Cu-cub/C, wherein the CoPc and Cu-cub share an interface, and CoPc-C/Cu-cub, wherein the CoPc is loaded first on carbon black (C) before mixing with the Cu-cub. The electrocatalytic measurements of these two catalysts show that the faradaic efficiency towards C-2 products almost doubles for the CoPc-Cu-cub/C, whereas it decreases by half for the CoPc-C/Cu-cub, compared to the Cu-cub/C. Our results highlight the importance of a direct contact between the CO-generating molecular catalyst and the Cu to promote C-C coupling, which hints at a surface transport mechanism of the CO intermediate between the two components of the tandem catalyst instead of a transfer via CO diffusion in the electrolyte followed by re-adsorption.

ROYAL SOC CHEMISTRY2023

Investigation of Ethylene and Propylene Production from CO2 Reduction over Copper Nanocubes in an MEA-Type Electrolyzer

Raffaella Buonsanti, Valery Okatenko

Previous work carried out in fully liquid environ-ments and at low current densities has demonstrated that highly uniform faceted copper nanocrystals display different selectivity profiles in CO2 reduction compared to polycrystalline copper. As part of ongoing upscaling efforts, it is a matter of interest to investigate whether the high selectivity toward ethylene of copper nanocubes, which show a preferential (100) orientation, is maintained in gas-fed electrolyzers, thus enabling the energy-efficient production of this valuable commodity chemical at industrially relevant current densities. In this work, we assessed the electrochemical CO2 reduction reaction performance of highly uniform copper nanocubes loaded onto gas diffusion electrodes (GDEs) in a zero-gap device. The copper nanocube-loaded GDEs maintained high Faradaic efficiencies toward ethylene at elevated total current densities, resulting in higher overall partial current densities toward this product compared to benchmark electrodes. Interestingly, CO2 reduction to propylene, albeit with low partial current densities, was also observed. However, double-layer capacitance measurements revealed that the performance observed at high current densities is significantly influenced by electrode flooding. The findings of this study can inform future efforts geared toward optimizing the electrodes with this promising class of catalysts.

AMER CHEMICAL SOC2022