Mn-Based Single Atoms and Nanocrystal Carbon Aerogels for CO 2 Capture and Energy Storage

The CO 2 adsorption and energy storage characteristics of Mn-based single atoms (SAs) and nanocrystals (NCs) (Mn sites stabilized by Mn–O bonds) arrayed in carbon aerogels (CAs), synthesized through a facile/one-pot synthesis route, are evaluated in detail. This involves studying the physiochemical properties of doped CAs with different manganese(II) acetate tetrahydrate ((CH 3 COO) 2 Mn·4H 2 O) loadings and correlating it with CO 2 adsorption and energy storage efficiency. Pyrolysis of gel under an inert atmosphere leads to decomposition of (CH 3 COO) 2 Mn·4H 2 O-induced activation of CAs. This dual role of (CH 3 COO) 2 Mn·4H 2 O as a pore-activating agent and catalyst has a significant impact on morphology and porosity. The single ions/nanocrystals of Mn generated thereof act as efficient catalysts, aiding the CO 2 adsorption and energy storage. The developed material shows strong potential for direct air capture (DAC), exhibiting remarkable CO 2 capture ability (2.54 mmol·g –1 at 15 mbar) along with high specific capacitance ( C sp ) (136.4 F·g –1 at 0.5 A·g –1 using 1 M KOH solution) and excellent stability of 92% after 3000 cycles at 1 A·g –1 .