Fikile R. Brushett, Assistant Professor, Department of Chemical Engineering

The development of energy efficient carbon dioxide (CO₂) electroreduction processes would simultaneously curb anthropogenic CO₂ emissions and provide sustainable pathways for fuel generation. While significant efforts have focused on heterogeneous CO₂ electroreduction to products such as carbon monoxide, formic acid, and methanol; no process has been able to demonstrate both high energetic efficiencies (≥ 60-70%) and high current densities (≥ 150 mA/cm²).  A key challenge is translating our investment in performance nanomaterials to meso- and microarchitectures within electrochemical cells under realistic operating conditions. Here we propose to develop microporous metal foam electrodes with nanostructured electrocatalysts directly deposited onto the foam surface for high-performance CO₂ conversion.  Metal foams hold two key advantages: 1) their porous nature facilitates extended tunable electrochemical interfaces without sacrificing transport of reactants and ions; and 2) they can act as a conductive substrate for the direct deposition of highly-active surface alloys eliminating the need for conductive additives and binders (which may degrade or promote side reactions). We will focus on CO-selective catalysts (e.g ., Ag, Au) as this represents the simplest CO₂ conversion reaction and has been demonstrated at moderate efficiencies (albeit at low currents).  Direct deposition enables ground-up construction of nanostructures using bath conditions (e.g. composition), delivery mechanism (e.g., diffusive, convective), and applied potential (for electrodeposition) as tools to control structure, phase, and surface characteristics. We will systematically investigate the structure-activity-stability relationships of the deposited catalysts and electrodes using electroanalytical and physical characterization techniques. Of particular interest will be catalysts deposited under transport limiting conditions (desirable for high-throughput manufacturing) and catalyst-substrate interactions (determines durability). The success of this project would enable efficient CO production at the large-scale which, when coupled with hydrogen generation from renewables enables the carbon-neutral synthesis gas production needed to generate liquid fuels for heavy duty transportation applications.