Ab Initio Design Principles for Excited-State Desorption in Heterogeneous Catalysis

Heterogeneous photocatalysis has drawn attention in recent decades due to its ability to dramatically speed up reaction rates, enhance selectivity amongst multiple products, and open new reaction pathways. Despite significant experimental progress, the accurate theoretical predictions about these phenomena are difficult to make due to their chemical complexity. Here, apply many-body perturbation theory (MBPT) to accurately compute excited state potential energy surfaces (PESs) for the proton desorption reaction from a rutile TiO2 (110) surface. We find sensitive dependence of the excited states on the position of the adsorbate, including sharp variations in the excited state PESs and intersections of the ground and excited states. The excited state PESs are qualitatively different from the ground state and greatly favor desorption with activation barriers as low as half the ground state barrier. Through analysis of mean-field and excited-state wavefunctions, we deduce general design principles for desorption reactions in excited-state catalysis. This work demonstrates the applicability of MBPT to the study of heterogeneous photocatalysts, and provides the framework to rigorously analyze reaction dynamics in the excited state from first principles.