Predicting the suitability of aqueous solutions of deep eutectic solvents for preparation of co-continuous porous carbons via spinodal decomposition processes

Spinodal decomposition (SD) processes have proved effective for the synthesis of macro- and mesoporous materials. Despite the theoretical aspects of SD processes are well understood, finding the proper experimental conditions – both the components as well as the ratio in which they have to be combined – to attain co-continuous structures is a non-predictable and quite tedious process, typically based on trial and error. The challenge is finding a “tool” capable to predict the suitability of a particular starting solution to undergo SD processes. Here in, we used aqueous solutions of deep eutectic solvents (DESs) for the preparation via SD of co-continuous porous carbons, the morphologies of which ranged from spinodal to aggregates-of-particles-like just depending on dilution. Despite the starting DES/H2O binary mixture was macroscopically homogeneous, Brillouin spectroscopy revealed the occurrence of certain nanostructural rearrangements within a dilution range that coincided with that used for preparation of carbons with morphologies transitioning from spinodal to aggregates-of-particles-like. Moreover, carbons exhibited a noticeable degree of heteroatom co-doping – e.g. N and P – and proved particularly effective for CO2 capture with adsorptions of up to 4.7 mmol/g at 0 °C and 760 mbar.