Carbon Capture in Polymer-based Electrolytes

Nanoparticle organic hybrid materials (NOHMs) have been proposed as excellent electrolytes for combined CO capture and electrochemical conversion due to their conductive nature and chemical tunability. However, CO capture behavior and transport properties of these electrolytes after CO capture have not yet been studied. Here, we use a variety of nuclear magnetic resonance (NMR) techniques to explore the carbon speciation and transport properties of branched polyethylenimine (PEI) and PEI-grafted silica nanoparticles (denoted as NOHM-I-PEI) after CO capture. Quantitative C NMR spectra collected at variable temperatures reveal that absorbed CO exists as carbamates (RHNCOO or RR'NCOO) and carbonate/bicarbonate (CO/HCO). The transport properties of PEI and NOHM-I-PEI studied using H pulsed-field-gradient NMR, combined with molecular dynamics simulations, demonstrate that coulombic interactions between negatively and positively charged chains dominate in PEI, while the self-diffusion in NOHM-I-PEI is dominated by silica nanoparticles. These results provide strategies for selecting adsorbed forms of carbon for electrochemical reduction.