Understanding the Influence of Cation Doping on the Surface Chemistry of NaTaO3 from First Principles

Sodium tantalate, NaTaO₃, has attractedinterest as one of the few photocatalysts capable to performoverall water splitting, that is, simultaneously produce oxygenand hydrogen from water. In particular, an interesting and notfully understood observation is that the efficiency of NaTaO₃ increases dramatically in the presence of cation doping. Toobtain better insight into the origin of this effect, we usefirst-principles calculations to investigate the fundamentalstructural, electronical, and chemical properties of pristineand Sr-doped NaTaO₃, a system for which severalexperimental studies have recently become available. Ourresults show that Sr donor−acceptor codoping at Na and Ta sites significantly reduces the formation energy of the Sr dopants.Further study of the energetics of the oxygen evolution reaction (OER) shows a substantial reduction of the OER overpotentialfor the codoped material, consistent with recent suggestions that codoping is crucial for increasing NaTaO₃’sefficiency. Thedetailed insights provided by our work could benefit the design and preparation of new efficient catalysts based on NaTaO₃.