(705c) A Comprehensive Study of Electrochemical Reduction of Captured CO2 in Amine-Based Capture Agents on Transition Metal Surfaces: Finding Activity and Stability Descriptors.

The direct electrochemical captured CO₂ reduction reaction (c-CO₂RR) is an emerging approach in carbon capture and utilization, which does not include a step where CO₂ is released (thermally) from the capture agent. The systematic exploration of c-CO₂RR is demonstrated through comparison with traditional electrochemical CO₂ reduction reaction (CO₂RR) systems, aiming to unveil stability and activity descriptors on transition metals using experimental and theoretical approaches.¹ Two significant phenomena arise in c-CO₂RR, distinguishing it from CO₂RR. These include the prevalence of the competing hydrogen evolution reaction (HER), and the rapid corrosion and restructuring of the catalyst in the presence of the CO₂-amine adducts. The dominance of HER in c-CO₂RR is elucidated by the electrostatic attraction of the protonated amine and the repulsion of captured CO₂ towards the electrode, leveraging the potential of zero charge (PZC). The stability of catalysts in c-CO₂RR environments is a function of the applied potential and cannot be readily predicted via binding energy descriptors typically employed in forecasting CO₂RR activities. Three distinct trends are observed experimentally under c-CO₂RR testing: i) Cu, and Sn undergo corrosion under open circuit conditions, predominantly producing hydrogen, ii) Au and Ag show activity in reducing dissolved CO₂ and undergo restructuring under cathodic potentials, and iii) Ti does not corrode at open circuit potentials generating hydrogen as the sole reduction product. In addition, the steric effect of bulky amines such as dimethylamine experimentally shows inhibition of Cu catalyst corrosion and suppression of HER. This underscores the necessity for further development of activity and stability descriptors beyond those established for CO₂RR.

1. Choi, Jounghwan, et al. "Direct Electrochemical Reduction of Ammonium Carbamate on Transition Metal Surfaces: Finding Activity and Stability Descriptors beyond those for CO2 Reduction." (2024).