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Fabrication of Fe-doped SrTiO3 photocatalyst with enhanced dinitrogen photofixation performance
摘要： SrTiO3 as semiconducting photocatalyst has been extensively investigated due to its band edges meeting the thermodynamic requirements for water splitting, but a few attention has been concentrated on its application in the NH3 synthesis via N2 photofixation process. Herein, Fe-doped SrTiO3 (FexSr1-xTiO3) products (0 ≤ x ≤ 0.20) were synthesized via a hydrothermal process followed by calcination at 700oC. All FexSr1-xTiO3 products (0.03 ≤ x ≤ 0.20) deliver an enhanced N2 fixation ability, and FexSr1-xTiO3 (x = 0.10) achieves the best NH3 production activity of 30.1 μmol g-1 h-1, which is 3.2-hold higher than that of SrTiO3 alone. Once the x value is higher than 0.10, FexSr1-xTiO3 will transform into composites containing Fe-doped SrTiO3 and α-Fe2O3, which acts as charge recombination sites, thus causes a decreased N2 fixation activity. Further investigations demonstrate that the surface Fe3+-doped sites can not only chemisorb and activate N2 molecules, but also promote the interfacial electron transfer from Fe-doped SrTiO3 to N2 molecules, and thus significantly improve the N2 fixation ability. The present Fe-doped SrTiO3 products exhibit characteristic features such as stable and efficient N2 fixation ability as well as simultaneous realization of N2 reduction and H2O oxidation without co-catalyst, which are of significance in artificial photosynthesis with H2O as electron and proton sources.
关键词： Photocatalysis,Fe-doped SrTiO3,Dinitrogen photofixation,N2 molecule activation
更新于2025-11-21 11:01:37
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Origin of Ferroelectricity in Epitaxial Si-doped HfO2 Films
摘要： HfO2-based unconventional ferroelectric (FE) materials were recently discovered and have attracted a great deal of attention in both academia and industry. The growth of epitaxial Si-doped HfO2 films has opened up a route to understand the mechanism of ferroelectricity. Here, we used pulsed laser deposition (PLD) to grow epitaxial Si-doped HfO2 films in different orientations of N-type SrTiO3 substrates. Using piezoforce microscopy, polar nanodomains can be written and read, and these domains are reversibly switched with a phase change of 180o. Films with different thicknesses displayed a coercive field Ec and a remnant polarization Pr of approximately 4～5 MV/cm and 8～32 μC/cm2, respectively. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) results identified that the as-grown Si-doped HfO2 films have strained fluorite structures. The ABAB stacking mode of the Hf atomic grid observed by HRTEM clearly demonstrates that the ferroelectricity originates from the noncentrosymmetric Pca21 polar structure. Combined with soft X-ray absorption spectra (XAS), it was found that the Pca21 ferroelectric crystal structure manifested as O sublattice distortion by the effect of interface strain and Si dopant interactions, resulting in further crystal-field splitting as a nanoscaled ferroelectric ordered state.
关键词： HRTEM,PLD,XRD,Ferroelectricity,PFM,XAS,Epitaxial Si-doped HfO2 thin films,N-type SrTiO3 substrates
更新于2025-11-14 17:04:02
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Interface properties of nonpolar LiAlO2/SrTiO3 heterostructures
摘要： Advances in creating metal oxide heterostructures have received a great deal of attention because novel properties like two-dimensional electron gas (2DEG), which was first found in LaAlO3/SrTiO3 interface, while does not exist in the bulk materials. To extend the study on 2DEG, we investigate the electronic property of interesting nonpolar/nonpolar LiAlO2/SrTiO3 heterostructure (also perovskite/nonperovskite oxide heterostructure), with and without oxygen vacancies by first-principles calculations. Two types of interfaces, SrO/LiAlO2 and TiO2/LiAlO2 interfaces, were modeled with the stable stacking configurations. Oxygen vacancies at LiAlO2/SrTiO3 interface induce the carriers in this system. there is no 2DEG behavior detected. Our results show that three-dimensional transport behavior occurs in the perovskite/non-perovskite oxide interface.
关键词： Metal oxide heterostructures,First-principles calculations,Oxygen vacancies,LiAlO2,SrTiO3
更新于2025-09-23 15:23:52
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Construction of Strontium Titanate/Binary Metal Sulfide Heterojunction Photocatalysts for Enhanced Visible-Light-Driven Photocatalytic Activity
摘要： A novel strontium titanate/binary metal sulfide (SrTiO3/SnCoS4) heterostructure was synthesized by a simple two-step hydrothermal method. The visible-light-driven photocatalytic performance of SrTiO3/SnCoS4 composites was evaluated in the degradation of methyl orange (MO) under visible light irradiation. The photocatalytic performance of SrTiO3/SnCoS4-5% is much higher than that of pure SrTiO3, SnCoS4, SrTiO3/SnS2 and SrTiO3/CoS2. The SrTiO3/SnCoS4 composite material with 5 wt.% of SnCoS4 showed the highest photocatalytic efficiency for MO degradation, and the degradation rate could reach 95% after 140 min irradiation time. The enhanced photocatalytic activity was ascribed to not only the improvement of visible light absorption efficiency, but also the construction of a heterostructure which make it possible to effectively separate photoexcited electrons and holes in the two-phase interface.
关键词： visible-light-driven,SnCoS4,heterojunction,degradation,SrTiO3
更新于2025-09-23 15:23:52
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Room-temperature multiferroic and magnetodielectric properties of SrTiO3/NiFe2O4 composite ceramics
摘要： Various xNiFe2O4 ? (1-x)SrTiO3 (x = 0.04, 0.05, 0.1, 0.2) composite ceramics were prepared using sol–gel method and two-step calcination. The composite ceramics possessed no impurities and exhibited obvious magnetic properties (22.8 emu/g at x = 0.2). The magnetic second phase imposed strain effects on the SrTiO3 matrix to induce ferroelectricity. Strain values of (001) and (110) crystal planes were ~2.9% and ~1.3%. The tetragonal phase transition was evident in the Raman spectra. The remanent and maximum polarizations were 1.4 and 15.8 μC/cm2, respectively, in ceramic with 10 mol.% NiFe2O4. The dielectric permittivity was tuned with 1.6% change rate at 50 kHz and 10000 Oe.
关键词： Phase transition,Ferroelectricity,Strains,SrTiO3,Magnetodielectric
更新于2025-09-23 15:22:29
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Effect of Terraces at the Interface on the Structural and Physical Properties of La <sub/>0.8</sub> Sr <sub/>0.2</sub> MnO <sub/>3</sub> Thin Films
摘要： Employing atomic force microscopy, transmission electron microscopy and the second harmonic generation technique, we carefully explore the structural properties of 6-unit-cell-thick La0.8Sr0.2MnO3 films grown on SrTiO3 with atomically flat TiO2-terminated terraces on the surface. The results clearly demonstrate that the terraces on the surface of TiO2-terminated SrTiO3 can improve the layer-by-layer epitaxial growth of the manganite films, which results in uniform film coverage at the beginning of growth and thus reduces the substrate-induced disorder at or near the interface. Comparing the magnetic and transport properties of La0.8Sr0.2MnO3 films with the thicknesses varying from 6 unit cells to 80 unit cells grown respectively on as-received SrTiO3 and TiO2-terminated SrTiO3, it is found that these atomically flat terraces on the surface of TiO2-terminated SrTiO3 can greatly enhance the Curie temperature and conductivities of the ultrathin La0.8Sr0.2MnO3 films with thickness less than 50 unit cells, while no obvious difference is detected in the magnetic and transport properties of the 80 unit-cell thick films.
关键词： La0.8Sr0.2MnO3,transport properties,SrTiO3,terraces,magnetic properties,structural properties
更新于2025-09-23 15:21:21
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Millimeter-sized magnetic domains in perpendicularly magnetized ferrimagnetic Mn <sub/>4</sub> N thin films grown on SrTiO <sub/>3</sub>
摘要： The use of epitaxial layers for domain wall-based spintronic applications is often hampered by the presence of pinning sites. Here, we show that when depositing Mn4N (10 nm) epitaxial films, the replacement of MgO(001) by SrTiO3(001) substrates allows minimizing the misfit, and to obtain an improved crystalline quality, a sharper switching, a full remanence, a high anisotropy and remarkable millimeter-sized magnetic domains, with straight and smooth domain walls. In a context of rising interest for current-induced domain wall motion in rare-earth ferrimagnets, we show that Mn4N/SrTiO3, which is rare-earth free, constitutes a very promising ferrimagnetic system for current-induced domain wall motion.
关键词： domain wall motion,Mn4N,ferrimagnetic,spintronics,SrTiO3
更新于2025-09-23 15:21:21
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Highly conductive two-dimensional electron gas at the interface of Al2O3/SrTiO3
摘要： We create a two-dimensional electron gas at the Al2O3/SrTiO3/LaAlO3 heterostructures using pulsed laser deposition, which exhibits a decreasing sheet resistance with increasing growth temperatures of Al2O3 films. Structural characterizations of films are confirmed by cross-sectional transmission electron microscopy. Compared with these heterostructures with Al2O3 films deposited on pristine SrTiO3 and TiO2-terminated SrTiO3 substrates, the Al2O3/SrTiO3/LaAlO3 heterostructures are more conductive. X-ray photoelectron spectroscopy indicates the formation of oxygen vacancies at the SrTiO3 side of the interface, which results from the redox reactions by reducing SrTiO3 films. Furthermore, the existence of oxygen vacancies on the SrTiO3 side is verified by a blue-light emission.
关键词： Al2O3/SrTiO3/LaAlO3 heterostructures,pulsed laser deposition,oxygen vacancies,two-dimensional electron gas,conductivity
更新于2025-09-23 15:21:21
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Photocatalytic degradation of 4-chlorophenol with the use of FTO/TiO2/SrTiO3 composite prepared by microwave-assisted hydrothermal method
摘要： Microwave-assisted hydrothermal method was applied to obtain SrTiO3 photocatalyst by transformation of a thin TiO2 layer deposited on the conducting solid substrate (FTO-glass) via dissolution-precipitation reaction in alkaline solution. The influence of Sr2+ ions concentration on crystallinity, composition as well as photoelectrochemical and photocatalytic properties of the resultant materials was investigated. The XRD studies indicated the presence of some amount of co-deposited SrSiO3 due to reaction of metasilicates released from the glass substrate (not covered with FTO film). However, the process of glass dissolution was substantially prevented by protection of the back side of the sample with a Teflon tape. The best activity in photodecomposition of 4-chlorophenol under irradiation with 365 nm diode was obtained for FTO/TiO2/SrTiO3 composite fabricated in 6 h synthesis in the solution containing 0.1 M Sr(NO3)2, at temperature of 180 °C. The photoelectrochemical properties of the composites and FTO/TiO2 electrode were studied in the solution of Na2SO4 under illumination with a xenon lamp. The increased photocurrent density and longer electron lifetime for the hybrid system in comparison to those of TiO2 was discussed in terms of suppressed recombination rate due to formation of TiO2/SrTiO3 interface. It was also found that the side product, SrSiO3, reveals an excellent adsorption properties with respect to methylene blue and therefore, the system SrTiO3/TiO2/FTO/glass/SrSiO3 may be used as bifunctional composite for adsorption and photocatalysis.
关键词： 4-Chlorophenol photodecomposition,Photocatalysis,SrSiO3,Photoelectrochemical properties,Microwave-assisted hydrothermal synthesis,TiO2/SrTiO3,Electron lifetime
更新于2025-09-23 15:21:21
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Room temperature synthesis of CdS/SrTiO3 nanodots-on-nanocubes for efficient photocatalytic H2 evolution from water
摘要： Spontaneous solar-driven water splitting to generate H2 with no pollution discharge is an ideal H2 generation approach. However, its ef?ciency remains far from real application owing to the poor light-harvesting and ultrafast charge recombination of photocatalysts. To address these issues, herein, we employed a novel but simple chemical bath deposition (CBD) method to construct CdS/SrTiO3 nanodots-on- nanocubes at room temperature (ca. 25 (cid:1)C). The as-synthesized nanohybrids not only expand light absorption from ultraviolet (UV) to visible light but also signi?cantly retard charge recombination owing to the well-de?ned heterostructure formation. As a result, the CdS/SrTiO3 exhibits high photocatalytic performance with H2 evolution rate of 1322 lmol g(cid:1)1 h(cid:1)1, which is 2.8 and 12.2 times higher than that of pristine CdS and SrTiO3, respectively. This work provides a universal approach for the heterostructure construction, and inspired by this, higher ef?cient photocatalysts for H2 evolution may be developed in the near future.
关键词： Nanoheterostructure,H2 generation,Room temperature,CdS/SrTiO3,Photocatalyst
更新于2025-09-23 15:21:21