Theory-Guided Discovery of Ion-Exchanged Poly(heptazine imide) Photocatalysts Using First-Principles Many-Body Perturbation Theory

Poly(heptazine imides) (PHI) show strong promise in photocatalysis, but limited control over electronic properties continues to constrain their full potential. We modulated PHI’s photocatalytic activity to overcome this limitation by incorporating mono-, di-, and trivalent metal cations into its framework. We employed calculations based on many-body perturbation theory─a highly accurate approach for electronic structure calculations─which provides improved accuracy in quasiparticle energy predictions compared to conventional density functional theory, particularly for band gaps and excitonic properties, to elucidate the underlying mechanisms. The coupling between exchanged metals and the resulting…