Evaluation of CO 2 and H 2 O Adsorption on a Porous Polymer Using DFT and In Situ DRIFT Spectroscopy.

Numerous hyper-cross-linked polymers (HCPs) have been developed as CO 2 adsorbents and photocatalysts. Yet, little is known of the CO 2 and H 2 O adsorption mechanisms on amorphous porous polymers. Gaining a better understanding of these mechanisms and determining the adsorption sites are key to the rational design of improved adsorbents and photocatalysts. Herein, we present a unique approach that combines density functional theory (DFT), in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and multivariate spectral analysis to investigate CO 2 and H 2 O adsorption sites on a triazine-biphenyl HCP. We found that CO 2 and H 2 O adsorb on the same HCP sites albeit with different adsorption strengths. The primary amines of the triazines were identified as favoring strong CO 2 binding interactions. Given the potential use of HCPs for CO 2 photoreduction, we also investigated CO 2 and H 2 O adsorption under transient light irradiation. Under irradiation, we observed partial CO 2 and H 2 O desorption and a redistribution of interactions between the H 2 O and CO 2 molecules that remain adsorbed at HCP adsorption sites.