One major challenge to electrochemical conversion of CO2 to useful fuels and chemical products is the lack of efficient catalysts that can selectively direct the reaction to one desirable product and avoid the other possible side products. Making use of strong metal-oxide interactions has recently been demonstrated to be effective in enhancing electrocatalysis in the liquid phase. We have performed a systematic study on composition-dependent influences of metal-oxide interactions on electrocatalytic CO2 reduction, utilizing Cu/SnOx heterostructured nanoparticles supported on carbon nanotubes (CNTs) as a model catalyst system. By adjusting the Cu/Sn ratio in the catalyst material structure, we can tune the products of the CO2 electrocatalytic reduction reaction from hydrocarbon-favorable to CO-selective to formic-acid-dominant. In the Cu-rich regime, SnOx dramatically alters the catalytic behavior of Cu. The Cu/SnOx-CNT catalyst containing 6.2% of SnOx converts CO2 to CO with a high Faradaic efficiency of 89% and a jCO of 11.3 mA cm-2 at -0.99 V vs. the reversible hydrogen electrode (RHE), in stark contrast to the Cu-CNT catalyst on which ethylene and methane are the main products for CO2 reduction. In the Sn-richer regime, Cu modifies the catalytic properties of SnOx. The Cu/SnOx-CNT catalyst containing 30.2% of SnOx reduces CO2 to formic acid with a Faradaic efficiency of 77% and a jHCOOH of 4.0 mA cm-2 at -0.99 V, outperforming the SnOx-CNT catalyst which only converts CO2 to formic acid in a Faradaic efficiency of 48%.

Strong metal-oxide interactions and materials design for electrocatalytic CO2 reduction reactions

256th National Meeting (2018)

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