Issue 19, 2024

Spatial tuning of adsorption enthalpies by exploiting spectator group effects in organosilica carbon capture materials

Abstract

Functional gradient materials can process more complex tasks than a mixture of their homogeneous analogs. Generating such materials is difficult as it necessitates spatial control over chemical and/or structural properties. A gradient is a unique degree of freedom in hierarchical material architectures, and as such, biology has managed exploiting the full potential of graded structures. For instance, despite being present at a comparably low concentration (approaching 420 ppm in 2023), plants are capable of capturing carbon dioxide from the air. Binding occurs in the carboxysome, a complex entity characterized by pores with engineered surfaces composed of shell proteins that create a concentration gradient of CO2 towards an enzyme responsible for the first conversion step. The current paper hypothesizes that porous organosilica materials can mimic some of the features of the mentioned biological paragon. Primary amines as sites for interacting with CO2 are surrounded by spectator groups on bifunctional surfaces. It is found that the proper choice of the spectator group almost doubles the adsorption enthalpy. Above a critical density, the hydrophobic moieties create a quasi-solvent layer on the surfaces in which CO2 molecules dissolve. When the density of the spectator groups gradually changes inside a graded organosilica monolith, one obtains zones varying systematically in adsorption enthalpy. Directionality in affinity towards CO2 and controlled transport properties are realized.

Graphical abstract: Spatial tuning of adsorption enthalpies by exploiting spectator group effects in organosilica carbon capture materials

Supplementary files

Article information

Article type
Paper
Submitted
28 Febr. 2024
Accepted
03 Apr. 2024
First published
04 Apr. 2024
This article is Open Access
Creative Commons BY license

J. Mater. Chem. A, 2024,12, 11332-11343

Spatial tuning of adsorption enthalpies by exploiting spectator group effects in organosilica carbon capture materials

M. Evers, K. Hauser, W. G. Hinze, N. Klinkenberg, Y. Krysiak, D. Mombers and S. Polarz, J. Mater. Chem. A, 2024, 12, 11332 DOI: 10.1039/D4TA01381F

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