Enhancing the photocatalytic upcycling of polystyrene to benzoic acid: a combined computational-experimental approach for acridinium catalyst design.

Converting polystyrene into value-added oxygenated aromatic compounds is an attractive end-of-life upcycling strategy. However, identification of appropriate catalysts often involves laborious and time-consuming empirical screening. Herein, after demonstrating the feasibility of using acridinium salts for upcycling polystyrene into benzoic acid by photoredox catalysis for the first time, we applied low-cost descriptor-based combinatorial in silico screening to predict the photocatalytic performance of a family of potential candidates. Through this approach, we identified a non-intuitive fluorinated acridinium catalyst that outperforms other candidates for converting polystyrene to benzoic acid in useful yields at low catalyst loadings (≤5 mol%). In addition, this catalyst also proved effective with real-life polystyrene waste containing dyes and additives. Our study underscores the potential of computer-aided catalyst design for valorizing polymeric waste into essential chemical feedstock for a more sustainable future.

Exploring vibronic coupling in the benzene radical cation and anion with different levels of the GW approximation.

The linear vibronic coupling constants of the benzene radical cation and anion have been obtained with different levels of the GW approximation, including G0W0, eigenvalue self-consistent GW, and quasiparticle self-consistent GW, as well as DFT with the following exchange-correlation functionals: BLYP, B3LYP, CAM-B3LYP, tuned CAM-B3LYP, and an IP-tuned CAM-B3LYP functional. The vibronic coupling constants were calculated numerically using the gradients of the eigenvalues of the degenerate HOMOs and LUMOs of the neutral benzene molecule for DFT, while the numerical gradients of the quasiparticle energies were used in the case of GW. The results were evaluated against those of high level wave function methods in the literature, and the approximate self-consistent GW methods and G0W0 with long-range corrected functionals were found to yield the best results on the whole.

Deriving the vibronic coupling constants of the cyclopentadienyl radical with density functional theory and G0W0.

The vibronic coupling constants of the cyclopentadienyl radical have been calculated with G0W0, HF, and density functional theory (DFT) with various exchange-correlation functionals such as PBE, PBE0, LC-ωPBE, and the non-empirically tuned LC-ωPBE*. The vibronic coupling constants for HF and DFT were derived using the gradients of the eigenvalues of the degenerate HOMOs of the closed-shell cyclopentadienyl anion, while the gradients of the corresponding quasiparticle energy levels were used in the case of G0W0. The differences between the linear vibronic constants obtained using HF and DFT were found to be small and reduced further when the G0W0 correction is applied to HF and DFT. Finally, the linear vibronic coupling constants calculated with G0W0 were found to agree well with the values obtained using high level wave function methods in the literature, which suggests that G0W0 can be a useful tool toward the study of vibronic coupling.