Na/Mo co-doped PbTiO₃ for photocatalytic water oxidation and Z-scheme overall water splitting under visible light

Herein, we demonstrate a sodium/molybdenum (Na/Mo) co-doped ferroelectric PbTiO₃ for efficient photocatalysis under visible light. Doped with a high concentration of Mo⁶⁺, quasi-continuous new energy levels are successfully introduced below the conduction band minimum of PbTiO₃, giving rise to a band-to-band redshift of the absorption edge. The valence state difference of Mo⁶⁺ and Ti⁴⁺ in the doped PbTiO₃ is compensated by the Na dopant, thus effectively suppressing the formation of the recombination centres caused by Mo⁴⁺. Combined with the intrinsic built-in electric field in PbTiO₃, this Na/Mo co-doping strategy enables PbTiO₃ to exhibit superior water oxidation activity under visible light with threshold wavelength up to 550 nm, which also promotes overall water splitting under visible light in a Z-scheme photocatalytic system. This strategy provides a generally applicable solution to extend the visible light absorption spectrum and engineer electronic structures of ferroelectric materials for photocatalysis and other energy conversion applications.