Prediction of Feasibility of Polaronic OER on (110) Surface of Rutile TiO2

The polaronic effects at the atomic level hold paramount significance for advancing the efficacy of transition metal oxides in applications pertinent to renewable energy. The lattice-distortion localization of photoexcited carriers in the form of polarons plays a pivotal role in the photocatalysis. This investigation focuses on rutile TiO2, an important material extensively explored for solar energy conversion in artificial photosynthesis, specifically targeting the generation of green H2 through photoelectrochemical (PEC) H2O splitting. By employing Hubbard-U corrected and hybrid density functional theory (DFT) methods, we systematically probe the polaronic effects in the catalysis of oxygen evolution reaction (OER) on the (110) surface of rutile TiO2. Theoretical understanding of polarons within the surface, coupled with simulations of OER at distinct titanium (Ti) and oxygen (O) active sites, reveals diverse polaron formation energies within the lattice sites with strong preference for bulk and surface bridge oxygen (Ob) sites. Moreover, we provide the evidence for the facilitative role of polarons in mitigating OER. We find that hole polarons situated at the equatorial positions near the Ti - active site, along with bridge hole polarons distal from the Ob active site yield a reduction in OER overpotential by (4.6-6.5)%. We also find that having hole polarons stabilize the *OH, *O, and *OOH intermediate species when compared to case without hole polarons. This study unravels a detailed mechanistic insight into polaron-mediated OER, offering a promising avenue for augmenting the catalytic prowess of transition metal oxide-based photocatalysts catering to renewable energy requisites.