(509c) Dynamic Probe of CO2 Dissolving for CO2 Storage and Conversion Via Micro-IR Spectroscopy

Recently, many efforts have been spent on developing novel strategies for CO₂ storage and conversion to close the carbon cycle and mitigate the climate challenge. To obtain insightful understandings to these processes for further system optimization, here we develop a dynamic micro-IR spectroscopy to track and quantify the dissolving of CO₂ in various aqueous solutions under a wide pressure range up to ~ 60 atm (at which point gaseous CO₂ starts to liquefy). As CO₂ molecules starting to interact with H₂O in the solution, dynamic micro-IR tracking shows that the quantized CO₂(g) rotational state transitions quench quickly while only the vibrational transition remains as an identical signal of dissolved CO₂(aq), indicating the molecular mechanism of CO₂ solvation to be the hindering of molecular rotation by water. The quantitative monitoring of CO₂ dissolving and desolvation reveals a quicker solvation kinetics than desolvation, rationalizing the widely observed CO₂ supersaturation in natural waterbodies. Employing the derived CO₂ molar extinction coefficient, we corelate the CO₂(aq) concentration with the Faradaic efficiency of electrocatalytic CO₂ conversion to formate and observe a high linearity, indicating a clear mechanism pattern of CO₂ electroreduction determined by CO₂ availability. Our dynamic CO₂ probing technique enables a further quantitative optimization on the design of CO₂ storage and conversion systems.