Search

SrTiO3 photocatalysts have been widely applied in overall water splitting reaction for their reasonable redox potential, whereas preventing the defects is crucial to improve the transition of photoexcited carriers influencing the photocatalytic performance. The defects in perovskite-type SrTiO3 were mainly Ti3+ and oxygen vacancies. Thence, little Ta5+ was designed to be doped in the B site for modulating the defect concentration. A series of advanced characterizations demonstrated that Ta5+ is helpful for Al3+ to penetrate the SrTiO3 lattice through lattice distortion, decreasing the Ti3+ defects. Meanwhile, the doping of slight Ta5+ facilitates the decrease in oxygen defect concentration, due to the formation of {Ta5+–O–Al3+}. Photoluminescence spectra and time-resolved fluorescence spectroscopy uncover that the charge carrier separation of SrTiO3 was enhanced by slight Ta5+. However, the excessive Ta5+ greatly promoted form the oxygen defect and Ti3+ species, leading to severe recombination of photogenerated carriers, which significantly reduced the photocatalytic activity. As a result, the optimized sample showed significant improvement in photocatalytic activity compared to the pure SrTiO3. [ABSTRACT FROM AUTHOR]

[Display omitted] • Al-doped SrTiO 3 nanoparticles with non-equivalent facets exposure were successfully prepared. • Polymerizable method assisted Al3+ uniformly entering into SrTiO 3 analyzed by DFT calculation. • The synergistic effect of the bulk Ti3+ defect and the increased surface oxygen vacancies induced by Al3+ additional substitution for Ti4+. • The optimized 2% Al3+-doped SrTiO 3 sample gives a good activity with AQE of 55.46% (λ = 365 nm). SrTiO 3 as a photocatalytic overall water splitting material has received extensive attention in recent years, while effectively suppressing Ti3+ is the key to enhancing the photocatalytic performance. Herein, a polymerizable complexation method is employed to enable Al3+ uniformly enter into SrTiO 3 lattice for reducing Ti3+, and substituting Ti4+ with the formation of oxygen vacancy. Thus, the photogenerated carrier transport is promoted, and the resulting appropriate surface oxygen vacancy is also conducive to the adsorption of water molecules and OH*. The optimized 2% Al3+-doped SrTiO 3 possesses a lower Ti3+ concentration, compared with the same sample prepared by the solid-phase griding method. Consequently, 2% Al-STO sample deposited co-catalysts achieves the highest activity and durability with the H 2 and O 2 evolution rates of 1.256 mmol·h−1 and 0.692 mmol·h−1 (0.04 g catalyst), respectively, corresponding to the AQE value of 55.46% at 365 nm. The characterizations and DFT calculation results reveal that the uniform Al3+ doping promotes the increase in the surface oxygen vacancy, which is beneficial for accelerating the reduction reaction and facilitating carrier separation and migration, therefore enhancing the overall water splitting reaction. [ABSTRACT FROM AUTHOR]

The trace high-oxidation-state V ion is designed to localize the defect charge for suppressing the formation of Ti3+ deep trap in SrTiO 3. This is an effective strategy to finely adjust the defect engineering for boosting solar water splitting. [Display omitted] • Doping trace V ion into SrTiO 3 can promote the reaction of overall water splitting. • The V ion prefers to localize the defect charge cooperated with the Al3+ around it. • The localization of defect charge suppresses the formation of deep trap. • Increasing shallow defect state and defect-charge amount will boost the activity. The deep trap such as Ti3+ in SrTiO 3 has a great influence on its photocatalytic performance in overall water splitting, acting as a recombination center of carriers. The applied defect engineering is focused on decreasing the Ti3+ concentration for enhancing solar water splitting mainly by doping low-valence metal ions, while the high-valence metal ions are noneffective. In this work, we doped trace V ions into SrTiO 3 accompanied by the Al3+ from the Al crucible, promoting the photocatalytic activity in overall water splitting based on the photocatalysis evaluation. A series of advanced techniques are used to characterize the chemical and physical property changes in SrTiO 3 aroused by V ions. Combined with the density functional theory, we found that trace V ions can cooperate with Al3+ to localize the defect charge around it, suppressing the formation of deep trap and increasing the amount of potential delocalized charge at shallow state, responsible for the boost of activity. This work provides another effective method to modulate SrTiO 3 -based photocatalysts in defect engineering. [ABSTRACT FROM AUTHOR]

Co-applying facet and defect engineering on SrTiO 3 is critical to enhance the photocatalytic activity, and the Sr2+ vacancies contribute to the greater modulation capacity in A-site for designing defect engineering. Here, we use advanced characterizations combined with density functional theory to elucidate the origin of K-modulated facet and defect in SrTiO 3 nanoparticles, thereby affecting the photocatalytic activities in overall water splitting. We found that the differences in binding strength between K 2 CO 3 and different facets led to the exposure of non-equivalent facets. Based on the facet engineering, we demonstrated that the K-doping process consisted of filling and substitution process, and the lowest defect concentration existed at their intersection and with a maximum bending degree of surface energy band between {100} and {110} facets. The optimized 3%K-doped SrTiO 3 composites have an intrinsic activity comparable to state-of-the-art catalysts. This work provides a significant theoretical guidance for rationally designing the high-performance SrTiO 3 -based photocatalysts. [Display omitted] • Sr2+ vacancies increase the modulation capacity in A-site for defect engineering on SrTiO 3. • The higher binding strength with K 2 CO 3 was demonstrated to promote the exposure of {110} facets. • K-doping in perovskite was found and illustrated to consist of fill and substitution processes. • The intersection of two processes has the lowest defect concentration proved by DFT calculation. • 3%K-SrTiO 3 composites have an intrinsic activity comparable to state-of-the-art catalysts. [ABSTRACT FROM AUTHOR]