Nonadiabatic Charge Carrier Dynamics in Rh-Doped BaTiO₃ for Photocatalytic Water Splitting

In this work, we performed a comprehensive first-principles investigation of the electronic structure, charge carrier relaxation dynamics, and photoluminescence properties of Rh-doped BaTiO₃, with a focus on photocatalytic water splitting applications. By combining hybrid DFT (HSE06), DFT+U, and Redfield theory, we elucidated how the doping site (Ti vs. Ba), dimensionality (bulk vs. surface), and aqueous environment govern the nonequilibrium behavior of photogenerated electron-hole pairs. Rh occupying Ti sites on the (001) surface exhibits a unique combination of extended visible-light absorption, ultrafast non-radiative relaxation, and efficient charge separation. These characteristics establish it as a promising photoanode material for photoelectrochemical water splitting.