Photocatalytic water splitting by N-TiO₂ on MgO (111) with exceptional quantum efficiencies at elevated temperatures

Photocatalytic water splitting is attracting enormous interest for the storage of solar energy but no practical method has yet been identified. In the past decades, various systems have been developed but most of them suffer from low activities, a narrow range of absorption and poor quantum efficiencies (Q.E.) due to fast recombination of charge carriers. Here we report a dramatic suppression of electron-hole pair recombination on the surface of N-doped TiO₂ based nanocatalysts under enhanced concentrations of H⁺ and OH⁻, and local electric field polarization of a MgO (111) support during photolysis of water at elevated temperatures. Thus, a broad optical absorption is seen, producing O₂ and H₂ in a 1:2 molar ratio with a H₂ evolution rate of over 11,000 μmol g⁻¹ h⁻¹ without any sacrificial reagents at 270 °C. An exceptional range of Q.E. from 81.8% at 437 nm to 3.2% at 1000 nm is also reported.