We present a Hubbard U optimized density functional theory based study of band gap engineered doped SrTiO3 suitable for light sensitive applications. We tune the Hubbard U parameter Uopt to match the ...experimental direct band gap of SrTiO3. We benchmarked the DFT+Uopt derived density of states, band structure and optical properties with that of sophisticated Heyd–Scuseria–Ernzerhof (HSE06) hybrid functional simulations. The reliability of the DFT+U method is further tested in simulating stability of the cubic SrTiO3 from elastic tensor and density functional perturbation theory based phonon band structure calculations. Moreover, the DFT+Uopt simulated SrTiO3 Raman peaks are identified against the experimental observations found in existing literature. We red shift the energy band gap of SrTiO3 within the DFT+Uopt formalism from ultraviolet to visible range by incorporating different dopants such as Pt, S and Se which is consistent with recent HSE06 hybrid functional based simulations found elsewhere. The optical absorption simulations revealed steep absorption edges of doped SrTiO3 in the visible spectrum. Overall, the DFT+U approach successfully probed the potential of doped SrTiO3 in solar harvesting applications.
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•Comprehensive DFT+U Study of Undoped, Pt-, S- and Se Doped SrTiO3.•DFT+Uopt and Heyd–Scuseria–Ernzerhof Hybrid Functional Comparative Study of SrTiO3.•DFT+Uopt Elastic & Phonon Properties and Born Charge Tensor Simulation of SrTiO3.•DFT+Uopt based Electronic & Optical Properties and Raman Peak Simulation of SrTiO3.•Band Gap Shift of SrTiO3 to Visible Spectrum through Pt-, S- and Se Doping.
•Strontium titanate (ST) nanocubes were hydrothermally synthesized for PENG.•The supersonically sprayed ST/PVDF exhibited 250 pm·V−1 effective piezoelectric coefficient.•The ST/PVDF PENG produced an ...open-circuit potential of 17 V.•A tapping test with 21,000 cycles confirmed the PENG durability.•Electrical poling for 16 h enhanced the piezopotential of ST/PVDF PENG up to 31 V.
Many perovskites and their piezoelectric composites have been investigated for harvesting ambient mechanical energy over the past two decades; however, the prospects for their commercialization appear remote because of several practical challenges. Therefore, highly scalable supersonic cold-spraying technology was used to fabricate flexible piezoelectric films of poly(vinylidene fluoride) (PVDF) and a novel perovskite SrTiO3 (ST). Substantial shear stress was exerted on PVDF during cold spraying owing to the hydrothermally synthesized SrTiO3 nanocubes and supersonic velocity, and the resulting film delivered an effective piezoelectric coefficient (69.6 pm·V−1) as confirmed by piezo-response force microscopy. As a result, the piezoelectric nanogenerator yields a maximum power of 130 µW at a load resistance of 0.9 MΩ. The composite film exhibited durability for 21,000 tapping cycles with 20 N applied force and 7 Hz frequency. The flexibility endurance was confirmed from 3000 bending cycles. PENG attached to knee delivered 1 and 2.3 V on bending to 45 and 90°, respectively. After electrical poling, the PENG was subjected to a 20 N tapping force that yielded a piezopotential of 31 V. To the best of our knowledge, this is the first time piezoelectricity was obtained using an ST/PVDF composite via mechanical energy harvesting. The flexible PENG film deposited by cold-spraying shows good potential for wearable self-powered devices.
We investigated the electrical transport properties of the SrTiO3/LaAlO3/SrTiO3 (STO/LAO/STO) trilayer interface system. We found that the trilayer exhibits superconductivity at temperatures below ...0.2 K. In the superconducting regime, the magnetoresistance (MR) of the system shows pronounced hysteresis, possibly due to the interplay of ferromagnetism and superconductivity. The magnitude of MR hysteresis strongly depends on the magnetic field sweep rate, and we observed a threshold field-sweep rate below which no MR is detected. At high sweep rates, the MR exhibits superconducting-normal-superconducting transition behavior. To explain these observations, we propose a model based on the ohmic heating from superconducting phase slip centers beneath Bloch-type magnetic domain walls in the ferromagnetic layer. Furthermore, we observed complex features in the MR curves that are likely due to domain wall motion in the system.
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•The interface electron system of (SrTiO3)7/(LaAlO3)1/SrTiO3 shows superconductivity below 170 mK.•The STO/LAO/STO shows hysteretic magnetoresistance below the superconducting transition temperature.•The MR is field-sweep-rate-dependent, and attributed to heating from phase slip centers at the magnetic domain boundaries.•Features observed in the MR may provide means to study the domain wall motion dynamics.
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•3DOM structure shows the slow light effect for improving light harvesting efficiency.•Sr component in 3DOM SrTiO3 enhances CO2 adsorption and activation properties.•Supported Pt NPs ...promote the separation efficiency of photogenerated carriers.•Ptn/3DOM-SrTiO3 catalysts show high activity and selectivity for CO2 reduction to CH4.•Surface enrichment of photogenerated electrons and activated CO2 are rate-determining steps.
Herein, we prepared the multifunctional photocatalysts of Pt nanoparticles (NPs)-decorated 3D ordered macroporous (3DOM) perovskite-type SrTiO3 (Ptn/3DOM-SrTiO3). The slow light effect of 3DOM photocatalysts improves the absorption of incident light. Surface alkaline-earth-metal Sr component enhances the adsorption and activation for CO2. Supported Pt NPs can trap and gather excited photoelectrons derived from SrTiO3, and Pt-SrTiO3 heterojunction improves the separation of photogenerated carriers. Ptn/3DOM-SrTiO3 photocatalysts exhibited high-efficient photocatalytic performance for CO2 reduction to CH4 product. Among the catalysts, Pt2/3DOM-SrTiO3 catalyst shows the highest catalytic activity and selectivity, i.e., its formation rate of CH4 (26.7 μmol g−1 h−1) is 20-fold that of commercial P25, and its selectivity to CH4 product is 86.7%. The catalytic mechanism for selective CO2 photoreduction to CH4 is proposed: the adsorption property for CO2 and surface enrichment of photoelectrons are two rate-determining steps to improve selectively photocatalytic reduction of CO2 to CH4.
In this work, a water splitting photoanode composed of a BiVO4 thin film surface modified by the deposition of a rhodium (Rh)‐doped SrTiO3 perovskite is fabricated, and the Rh‐doped SrTiO3 outer ...layer exhibits special photoelectrochemical (PEC) oxygen evolution co‐catalytic activity. Controlled intensity modulated photo‐current spectroscopy, electrochemical impedance spectroscopy, and other electrochemical results indicate that the Rh on the perovskite provide an oxidation active site during the PEC water oxidation process by reducing the reaction energy barrier for water oxidation. Theoretical calculations indicate that the water oxidation reaction is more likely to occur on the (110) crystal plane of Rh‐SrTiO3 because the oxygen evolution reaction overpotential on the (110) crystal plane is reduced significantly. Therefore, the obtained BiVO4/Rh5%‐SrTiO3 photoanode exhibits an optimized PEC performance. In particular, it facilitates the saturation of the photocurrent density. Thus, the presence of doped Rh in SrTiO3 can reduce the amount of noble metals required while achieving excellent and stable oxygen evolution properties.
The oxygen evolution reaction (OER) cocatalytic performance of Rh‐doped perovskite SrTiO3
is researched. Rh provides the main active sites for the OER and the overpotential over the Rh‐SrTiO3 (110) facet is significantly reduced. Rh‐doped SrTiO3 greatly reduces the amount of noble metals, but displays excellent oxygen evolution properties. It also takes into account the stability of perovskite materials.
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Spontaneous solar-driven water splitting to generate H2 with no pollution discharge is an ideal H2 generation approach. However, its efficiency 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 °C). The as-synthesized nanohybrids not only expand light absorption from ultraviolet (UV) to visible light but also significantly retard charge recombination owing to the well-defined heterostructure formation. As a result, the CdS/SrTiO3 exhibits high photocatalytic performance with H2 evolution rate of 1322 μmol g−1 h−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 efficient photocatalysts for H2 evolution may be developed in the near future.
Using simple solid state reaction route, the La and Fe doped SrTiO3 nanoparticle have been successfully synthesized. The effects of different dopant concentrations (1, 2, 3, 4 and 5 wt %) on the ...characteristics of the as-prepared samples were systematically investigated using various techniques. X-ray diffraction (XRD) investigation exhibit the formation of the cubic perovskite structure of all samples. Field emission scanning electron microscopy (FESEM) images have been confirmed the uniformity and particle size reduction of the samples with increasing of doping elements. Also, the increase of surface area from 9.7 m2/g for pure SrTiO3 to 64.2 m2/g for 5 wt% La-Fe doped SrTiO3 validated by Brunauer-Emmett-Teller (BET) studies. The UV–vis diffuse reflectance spectra (DRS) demonstrate the blue-shift of absorption tail for doped samples as well as reduction of band gap energies (from 3.2 eV to 2.72 eV) with the increase of the doped element. Photoluminescence (PL) analysis of the synthesis nanoparticle display defective states and decline in PL intensity as a result of the doping materials effect in SrTiO3. The 150 min of irradiation time, 0.6 g/L of catalyst dosage, and 5 ppm of initial MO concentration have been obtained as the optimum photocatalyst operating conditions. Also, the photocatalytic investigation reveals the enhancement of degradation rate of Methyl Orange (MO) under visible irradiation for the doped sample. The perfect photocatalytic activity at 4 wt% of Fe-La-doped SrTiO3 nanoparticles is around 19 times higher than that of pure SrTiO3 (96% compare to 5%). In the end, the photocatalytic performance mechanisms are deeply explained.
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•La and Fe doped SrTiO3 perovskite photocatalyst was successfully synthesized.•Effect doping elements on the characteristics of SrTiO3 was studied in detail.•Photocatalytic activity was enhanced almost 19 times with optimum doping.•Doped photocatalyst was stable and efficient through cyclic degradation experiment.
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