Strategies to Enhance the Rate of Proton‐Coupled Electron Transfer Reactions in Dye‐Water Oxidation Catalyst Complexes

Abstract

AbstractA thorough understanding of the proton‐coupled electron transfer (PCET) steps that are involved in photocatalytic water oxidation is of crucial importance in order to increase the efficiency of dye‐sensitized photoelectrochemical cells (DS‐PEC) for solar to fuel conversion. This work provides a computational investigation of the ground and excited state potential energy surfaces of PCET reactions in two supramolecular dye‐catalyst complexes for photocatalytic water splitting. The intrinsic reaction coordinate path is computed for the rate limiting PCET step in the catalytic cycle for both complexes. By using time‐dependent density functional theory calculations, we show that the ground and excited state potential energy surfaces have a (near) degeneracy in the region of the PCET transition state. We discuss two possible strategies that take advantage of this feature to accelerate the PCET reaction: (i) through optimizing the conditions for vibronic coupling by chemical design and synthesis or (ii) through populating the product state with appropriately tuned laser pulses.