Study of the K2Ti6-xZrxO13 (x = 0 - 1) solid solution for enhancing the photocatalytic hydrogen production: Oxygen vacancies playing an important role in the catalytic performance

Abstract The K2Ti6-xZrxO13 (x = 0–1) solid solution was prepared by the traditional solid-state synthesis method. The X-Ray diffraction patterns presented a proportional increase in the cell volume and crystal lattice distortion according to the increment of the Zr4+ species concentration in the reactant mixture. The morphological characterization showed a decrease in particle size average as a result of the zirconium presence due to crystal distortion. The photocatalytic performance was evaluated in the hydrogen evolution reaction in the presence of methanol. In this context, the K2Ti5ZrO13 solid solution exhibited the highest performance (72 μmolg−1 h−1) due to the higher presence of defects such as oxygen vacancies because of the Zr incorporation into the crystalline structure. In this context, these anionic defects can act as electron traps in bulk material and reduce recombination of charges; meanwhile, oxygen vacancies in surface create reactive Ti3+ ions, where the reactions of interest take place.