Predominance of aminated water interfaces on transition-metal nanoparticulate to enhance synergetic removal of carbonyls and inhibition of CO2 production.

In the context of the air quality co-benefits of carbon neutrality, conventional strategies for the end-of-pipe control aimed at reducing volatile organic compounds (VOCs) to carbon dioxide (CO2) require a more realistic revision. This study explored the synergetic removal of carbonyls with low carbon emission by amine-functionalized manganese dioxide (MnO2), obtained through a method involving freezing-thawing cycles. Molecular-level characterization revealed that an ordered array of interfacial water dimers (H5O2+, a class of water-proton clusters) on the MnO2 surface enhanced the robust bonding of metal sites with amino groups. Amine-functionalized MnO2 can be negatively charged under environmental acidity to further interfacial proton-coupled electron transfers. This cooperativity in interfacial chemical processes promoted the selective conversion of carbonyl carbons to bicarbonated amides (NH3+HCO3-), serving as a reservoir of CO2. In comparison to a commercially used 2,4-dinitrophenylhydrazine (DNPH) control, this approach achieved nearly complete removal of a priority carbonyl mixture containing formaldehyde, acetaldehyde, and acetone synergically. The formation of secondary organic compounds in the gas phase and CO2 off-gas were suppressed.