Engineered Electronic States of Transition Metal Doped TiO2 Nanocrystals for Low Overpotential Oxygen Evolution Reaction

Electrochemical oxygen evolution reaction (OER) involves high overpotential at the oxygen evolving electrode and thereby suffers significant energy loss in the proton exchange membrane water electrolyzer. To reduce the OER overpotential, precious ruthenium and iridium oxides are most commonly used as anode electrocatalyst. Here we report marked reduction in overpotential for the OER using transition metal (TM) doped TiO2 nanocrystals (NCs). This reduction in overpotential is attributed to d-orbitals splitting of the doped TMs in the TM-doped TiO2 NCs and their interactions with the oxyradicals (intermediates of OER) facilitating the OER. The d-orbital spitting of TMs in TM-doped TiO2 NCs is evident from the change in original pearl white color of undoped TiO2 NCs and UVvis absorption spectra.