Modeling Photoelectrochemical Water Oxidation and CO2 Reduction With DFT+U, DFT+D, and Heterogeneous Solvation

Identifying and developing efficient, economical, and feasible sustainable energy technologies is of great interest, and first-principles modeling based on Kohn-Sham Density Functional Theory (KS-DFT) can provide critical fundamental insight needed to engineer sunlight-powered CO₂-neutral energy conversion processes. However, depending on device materials and/or experimental conditions employed, standard KS-DFT alone will not be appropriate for accurate and physical predictions of these processes. We highlight recent findings from computational investigations that model and optimize electrocatalysis of first-row transition metal oxide photoelectrode materials using DFT+U methodology with ab initio derived U–J values. Surface water structures, mechanistic steps, as well as dopants that optimize electrocatalysis will be reported. We also discuss pyridinium-catalyzed photoelectrochemical CO₂ reduction with p-GaP photoelectrochemical cells. Here, treating the effects of van der Waals dispersion and solvation at the electrode due to the electrolyte is critically important to unraveling its complicated reaction mechanism. Our results indicate that pyridinium in these photoelectrochemical cells serendipitously plays a similar role as biological redox catalysts.