Mg modified LaTiO2N with ameliorated photocarrier separation for solar water splitting.

LaTiO 2 N is modified by Mg doping to construct solid solution series, i.e., LaTi 1−x Mg x O 2+y N 1−y (0 ≤ x ≤ 0.5). This modification effectively decreases the defect concentration (particularly bulk Ti3+ species and anion vacancies), increases the surface hydrophilicity, positively shifts the valence band top albeit it also enlarges the bandgap and induces Ti/Mg ordering when x ≥ 0.2. These competitive tensions render an optimal composition at LaTi 0.9 Mg 0.1 O 2+y N 1−y (x = 0.1) where both a low defect concentration and a disordered state of Ti/Mg can be reached, demonstrating much-improved photocarrier separation and exceptional photocatalytic activity with apparent quantum efficiency as high as 13.02 % at 420 ± 20 nm for O 2 -evolution. Overall water splitting (H 2 /O 2 molar ratio = 2/1) with good recycling stability has been realized by integrating LaTi 0.9 Mg 0.1 O 2+y N 1−y into a Z-scheme system. These findings justify the efficacy of Mg as a useful modulator to improve the photocatalytic performance of metal oxynitrides. [Display omitted] • Solid solution series LaTi 1−x Mg x O 2+y N 1−y (0 ≤ x ≤ 0.5) have been synthesized. • Mg doping modifies a number of important properties of LaTiO 2 N. • Optimal composition is found at x = 0.1 with exceptional photocatalytic activity. • An AQE as high as 13.02 % at 420 ± 20 nm has been attained for O 2 -evolution. • Z-scheme overall water splitting is achieved using Mg-modified LaTiO 2 N. [ABSTRACT FROM AUTHOR]