Electronic and electrocatalytic properties of PbTiO 3 : unveiling the effect of strain and oxygen vacancy.

First-principles calculations based on density-functional theory have been used to investigate the effect of biaxial strain and oxygen vacancy on the electronic, photocatalytic, and electrocatalytic properties of PbTiO 3 oxide. Our results show that PbTiO 3 has a high exciton binding energy and a band gap that can be easily moderated with different strain regimes. From a reactivity viewpoint, the highly exothermic adsorption of hydrogen atoms in both pristine and strained PbTiO 3 structures does not make it a potential electrocatalyst for the hydrogen evolution reaction. Fortunately, the presence of oxygen vacancies on the PbTiO 3 surface induces moderate adsorption energies, making the reduced PbTiO 3 suitable for hydrogen evolution reaction processes.