Heterogeneous electrochemical reduction of CO2 provides a pathway to address current issues in solar energy storage. We have recently developed a class of electrodeposited bismuth based materials that promote the electrocatalytic reduction of CO2 to CO with fast kinetics and high efficiencies in the presence of imidazolium ([Im]+) based RTILs. The metrics with which the Bi/[Im]+ systems drives electroreduction of CO2 is comparable to that observed using expensive precious metals, with Faradaic efficiencies and current densities for CO production of FECO ~ 90 % and jCO ~ 5–25 mA/cm2, respectively at applied overpotentials of ~ 300 mV. We have undertaken a multipronged study to elucidate the mechanistic pathways and molecular design principles that drive CO2 activation at the Bi/[Im]+ interface. A combination of spectroscopic, electroanalytical and computational methods has been used to interrogate the dynamics between electrocatalyst, RTIL and CO2 at the cathode/electrolyte interface and provide insight into the pathway(s) by which these systems activate CO2. To further understand how the RTIL influences the ability of Bi-cathodes to activate CO2, the electrochemistry of these catalysts in the presence of non-[IM]+ RTILs was also evaluated. These studies reveal that subtle modification of the RTIL structure, leads to a significantly different catalysis with CO2. Electrolysis of CO2 in the presence of these new generation RTILs using Bi-cathodes promotes the reduction of CO2 to yield formic acid, with selectivities as high as FEFA ~ 80% at jtot ~ 20–70 mA/cm2. We will discuss the catalytic plasticity that is displayed by these Bi/[RTIL] systems, along with implications for future development of catalyst/electrolyte combinations that can efficiently promote CO2 conversion.

Controlling the outcome of CO2 reduction at bismuth-film cathodes in the presence of room temperature ionic liquids

254th National Meeting (2017)

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