Decoding the CO ₂ Reduction Mechanism of a Highly Active Organometallic Manganese Electrocatalyst: Direct Observation of a Hydride Intermediate and Its Implications

The electrochemical reduction of CO2 is a promising route to convert intermittent renewable energy to storable fuels and valuable chemical feedstocks. To scale this technology for industrial implementation, a deepened understanding of how the CO2 reduction reaction (CO2 RR) proceeds will help converge on optimal operating parameters. Here, a techno-economic analysis is presented with the goal of identifying maximally profitable products and the performance targets that must be met to ensure economic viability-metrics that include current density, Faradaic efficiency, energy efficiency, and stability. The latest computational understanding of the CO2 RR is discussed along with how this can contribute to the rational design of efficient, selective, and stable electrocatalysts. Catalyst materials are classified according to their selectivity for products of interest and their potential to achieve performance targets is assessed. The recent progress and opportunities in system design for CO2 electroreduction are described. To conclude, the remaining technological challenges are highlighted, suggesting full-cell energy efficiency as a guiding performance metric for industrial impact. Show more

Practical electrochemical carbon dioxide (CO 2 ) conversion requires a catalyst capable of mediating the efficient formation of a single product with high selectivity at high current densities. Solid-state electrocatalysts achieve the CO 2 reduction reaction (CO 2 RR) at current densities ≥ 150 milliamperes per square centimeter (mA/cm 2 ), but maintaining high selectivities at high current densities and efficiencies remains a challenge. Molecular CO 2 RR catalysts can be designed to achieve high selectivities and low overpotentials but only at current densities irrelevant to commercial operation. We show here that cobalt phthalocyanine, a widely available molecular catalyst, can mediate CO 2 to CO formation in a zero-gap membrane flow reactor with selectivities > 95% at 150 mA/cm 2 . The revelation that molecular catalysts can work efficiently under these operating conditions illuminates a distinct approach for optimizing CO 2 RR catalysts and electrolyzers. Show more