Bare SrTiO3 Research Articles

Thermal and electrostatic tuning of surface phonon-polaritons in LaAlO3/SrTiO3 heterostructures

Phonon polaritons are promising for infrared applications due to a strong light-matter coupling and subwavelength energy confinement they offer. Yet, the spectral narrowness of the phonon bands and difficulty to tune the phonon polariton properties hinder further progress in this field. SrTiO3 – a prototype perovskite oxide - has recently attracted attention due to two prominent far-infrared phonon polaritons bands, albeit without any tuning reported so far. Here we show, using cryogenic infrared near-field microscopy, that long-propagating surface phonon polaritons are present both in bare SrTiO3 and in LaAlO3/SrTiO3 heterostructures hosting a two-dimensional electron gas. The presence of the two-dimensional electron gas increases dramatically the thermal variation of the upper limit of the surface phonon polariton band due to temperature dependent polaronic screening of the surface charge carriers. Furthermore, we demonstrate a tunability of the upper surface phonon polariton frequency in LaAlO3/SrTiO3 via electrostatic gating. Our results suggest that oxide interfaces are a new platform bridging unconventional electronics and long-wavelength nanophotonics.

Au nanoparticles dispersed polypyrrole-carbon black/SrTiO3 nanocomposite photocatalyst with rapid and stable photocatalytic performance

The current chaotic environmental situation especially water pollution prerequisites efficient novel photocatalysts for the proper treatment of these toxic structures through advanced oxidation process. However, the development of active photocatalytic structures requires further committed effort to ensure proper designing and essential band gap. In this report, an attempt has been made to fabricate a rapid and efficient photocatalyst based on SrTiO3 nanostructures, polypyrrole doped carbon black (PPyC) and Au nanoparticles to tackle serious problems of water contamination. Au@PPyC/SrTiO3 ternary photocatalyst was smoothly fabricated by sol gel route followed by ultrasonication and photoreduction technique. X-ray powder diffraction (XRD) studies revealed that SrTiO3 have cubic perovskite structure, while X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR) confirmed the formation of ternary framework among Au, PPyC and SrTiO3 nanostructures. Transmission electron microscopy (TEM) revealed that SrTiO3 possessed irregular porous nanoparticles ranging from 10 to 100 nm, whereas the PPyC appeared as well-ordered chain of beads or interconnected branches of nanoparticles. Modification of bare SrTiO3 to Au@PPyC/SrTiO3 significantly increases the surface area to 2.48 times than that of SrTiO3. The photocatalytic performance of the newly developed Au@PPyC/SrTiO3 photocatalyst has been tested on insecticide imidacloprid and on methylene blue (MB) dye. The current Au@PPyC/SrTiO3 photocatalytic framework exhibited ultrafast skills by removing 96.65% of imidacloprid just in 15 min and found to be ∼3.5 times more effective than bare SrTiO3. Besides this Au@PPyC/SrTiO3 photocatalyst was proven to be extremely destructive for resistant MB dye structure.

One-pot synthesis of Ag-modified SrTiO3: synergistic effect of decoration and doping for highly efficient photocatalytic NOx degradation under LED

Strontium titanate is an ideal cubic-structure perovskite oxide that finds application in hydrogen production and water pollutants degradation field. However, its photocatalytic activity is limited under UV irradiation due to its wide energy band bap (∼ 3.2 eV). To overcome this limitation, different strategies, such as metal-doping or metal-decoration, have emerged. Here, Ag-modified-SrTiO3 photocatalysts were prepared for the first time by a cheap, simple and sustainable approach based on the use of Ag-enriched wastewaters. The Ag-decorated SrTiO3 synthesized by a two steps method photodegraded by nearly 77% of NOx within 3 h. The Ag-modified SrTiO3 prepared by aone-pot synthesis led to a doubly modification of the oxide: Ag+ doping and Ag nanoparticles-decoration. In this case the use of Ag-enriched wastewaters led to poor photocatactivity of the photocatalyst, probably related to the presence of other metals in the waste. However, the use of a pure Ag precursor permitted the fabrication of a highly efficient material achieving complete photodegradation of NOx, exhibiting a photoactivity 4 times higher than bare SrTiO3 and 1.3 times more active than Ag-decorated material. The photocatalytic enhancement was attributed to the combined effect of Ag-doping and Ag-decoration on SrTiO3, which contributed to a narrow band gap (2.80 eV), as well as the formation of heterojunctions that promotes the separation of photogenerated charges, respectively. This material showed good stability during recycling tests, maintaining high performances after five cycles. Eventually, active species were identified using various scavengers by trapping holes and radicals generated during the photocatalytic degradation process.

Promoting active sites of Fe3+ ions in SrTiO3 nanosphere: A superior candidate for high performances of Dye-sensitized solar cell and Photocatalytic dye degradation

In the present exploration, the impurity like Fe is doped in the SrTiO3 (STO) in order to enhance the physical properties which in turn used to engineer the material for the specific applications like photoanode in Dye-sensitized solar cell (DSSC) along with the visible-light driven photocatalyst. X-ray diffraction (XRD) confirms the formation of cubic perovskite structured SrTiO3 nanoparticles. The UV-Vis studies reveal that the impurity energy level of the Fe3+ electron could be excited to the conduction band of the SrTiO3, resulting in light absorption in the visible region. The DSSC based on Fe doped STO photoanode shows a lower recombination rate of photogenerated carriers and a longer lifetime, as evidenced by Photoluminescence spectroscopy (PL), Incident Photon to Current Conversion Efficiency (IPCE) and Electrochemical Impedance Spectroscopy (EIS). Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) images show the spherical-like morphology. Energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) revealed the elements present in the material and chemical compositions. When compared with the bare STO photoanode, STF5 photoanode showed two fold increase in the highest power conversion efficiency (PCE) of 3.23 % with an open-circuit voltage (Voc) of 0.72 V, short circuit current (Jsc) of 7.32 mA cm-2, fill factor (FF) of 0.61 and four fold enhancement in IPCE of 41.18 %. Additionally, profit from the merits of STF5 photocatalyst showed a significantly enhanced photocatalytic efficiency (82 %) of methylene blue (MB) degradation under Visible light irradiation. The detailed results are presented and discussed.

Development of visible light-driven SrTiO3 photocatalysts for the degradation of organic pollutants for waste-water treatment: Contrasting behavior of MB & MO dyes

Semiconductor photocatalysts were utilized widely for degrading organic pollutants in water using the advanced, environment-friendly, low-cost, and highly efficient photocatalysis technique. There are various complex energy-consuming techniques used for the refinement of wastewater. However, the photocatalysis process is the cleanest technique used for degrading organic pollutants in wastewater into the water; carbon dioxide, other small molecules, and inorganic pollutants were reduced or oxidized into harmless substances.SrTiO3 nanoparticles (NPs) synthesized by the chemical method are the topic of attention among researchers because of their physical, chemical & photocatalytic properties under sunlight for water purification applications. This paper dealt with the study of The photocatalytic properties of SrTiO3 and its composites under sunlight irradiation. Here, we evaluated the photodegradation of methyl orange (MO) and methylene blue (MB) pollutants using SrTiO3 as a photocatalyst for de-ionized (DI) water and hard water, respectively. Later on, the ex-situ decoration of Ag and Au nanoparticles (NPs) on SrTiO3 NPs results in enhancing the photocatalytic activity of SrTiO3. This article shows the abnormal behaviour of MO degradation compared to MB dye because there was no degradation of methyl orange for both bare SrTiO3 and Ag, Au@SrTiO3 nanocomposites. However, for bare-SrTiO3, the photocatalytic degradation of MB dye for de-ionized and hard water was accomplished in 210 min and 300 min, respectively. Here, SrTiO3 with MB dye shows enhanced photocatalytic activity for de-ionized water than hard water, and thus we determined the degradation of SrTiO3 nanocomposites with DI water only. While in the case of SrTiO3 nanocomposites, degradation occurred in 210min for Ag and 180 min for Au in DI water which signifies that Au a better co-catalyst for photodegradation. Although, degradation of MO in both DI water and hard water does not show any photocatalytic activity even in 6 and 7 h, respectively, for bare SrTiO3 and its nanocomposites. Therefore, it gives an idea about the different behaviour of dyes in photocatalytic degradation of DI and hard water using bare SrTiO3 and noble metal doped SrTiO3 as photocatalysts for water remediation applications.At a glimpse, this work focus on the photocatalytic removal of various water pollutants using the efficient noble metal (Au & Ag) doped SrTiO3 as a photocatalyst and discusses the properties of those materials and also discuss the prospects for the utilization of those photocatalysts in complex form for the wastewater treatment.

Optimization of Plasmonic Copper Content at Copper-Modified Strontium Titanate (Cu-SrTiO3): Synthesis, Characterization, Photocatalytic Activity

Catalyst development still has a major impact on science today, as we can use catalysts to break down certain pollutants in an energy-efficient way. There is no comprehensive literature on the development of SrTiO3-based photocatalysts, so study in this area is justified. Related to this topic, here we report the facile preparation of surface-modified SrTiO3 photocatalyst, performed by plasmonic copper deposition. In the case of the copper-modified samples (0.25–3 wt.% Cu content), the photooxidation of phenol, as model contaminant, was almost 4–5 times higher than the bare SrTiO3. However, the photocatalytic activity was not linearly related to copper content, since the highest photoactivity was achieved at 1 wt.% copper content. The reason for the better activity was the plasmonic effect of copper, which increases the recombination time of charge separation on the catalyst surface. During slower recombination, more water is oxidized to hydroxyl radicals, which can lead to faster degradation of phenol.

Exceptional co-catalysts free SrTiO3 perovskite coupled CdSe nanohybrid catalyst by green pulsed laser ablation for electrochemical hydrogen evolution reaction

In this study, a facile and green PLAL technique was used to synthesize nanohybrids consisting of SrTiO3/CdSe, as efficient cathode material for electrocatalytic HER in a basic medium. Although pure SrTiO3 perovskite has poor electrocatalytic performance, but the addition of CdSe has significantly enhanced its electrocatalytic HER activity. Synergistic interactions between SrTiO3 and CdSe are critical to enhance the nanohybrid's electrocatalytic HER performance. An optimized concentration of SrTiO3/CdSe demonstrated a significant current density of -10 mA/cm2 at an overpotential of 224.2 mV, which is much better than the same current density achieved with bare SrTiO3 and CdSe alone at overpotentials of 375.9 mV and 399.4 mV, respectively. SrTiO3/CdSe nanohybrid follows intermediate hydrogen adsorption, which is explained by the Volmer-Heyrovsky step mechanism. The incorporation of CdSe into SrTiO3 improved the nanohybrid's electrocatalytic HER performance by increasing the electrochemical surface area and number of active sites, hence facilitating the electron transfer at the semiconductor-electrolyte interface.

Enhancing the short circuit current of a Dye-Sensitized Solar cell and photocatalytic dye degradation using Cr doped SrTiO3 interconnected spheres

In this work, different concentration of Cr doped SrTiO3 has been synthesized by co-precipitation technique and employed as a photoanode for Dye-Sensitized Solar Cells (DSSCs) by optimizing the Cr concentration. X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS) and UV–vis Diffuse Reflectance Spectroscopy (DRS) are used to examine the crystalline structure, shape, size, composition and optical response of the synthesized samples. Current density-Voltage (J-V) spectra reveal that Cr-STO-7 cell achieved the highest short circuit current (JSC) of 8.6 mA/cm2, open-circuit voltage (VOC) of 0.71 V and efficiency (η) of 3.71% whereas bare SrTiO3 (STO) achieved only the JSC of 5.7 mA/cm2, VOC of 0.54 V and η of 0.94%. The improvement is due to the lower charge transfer resistance (RCT) and charge recombination. It also serves as an effective material for Methylene Blue (MB) dye degradation. Among the samples, Cr-STO-7 achieved the highest photocatalytic efficiency of 88% under visible light illumination.

Preparation of SrTiO3/Bi2S3 Heterojunction for Efficient Photocatalytic Hydrogen Production

SrTiO3, Bi2S3, and SrTiO3/Bi2S3 heterojunction were prepared for efficient photocatalytic hydrogen production. SrTiO3/Bi2S3 heterojunction was prepared by different weight percentages of Bi2S3 (1, 3, 5, and 7%) with SrTiO3. SrTiO3 and Bi2S3 are exhibited in cubic and orthorhombic crystal structures, respectively. The morphologies of SrTiO3 and Bi2S3 have existed as nanocubic and bar-like structures, respectively. Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) results further confirmed the formation of SrTiO3/Bi2S3 heterojunction. The photoluminescence (PL) and electrochemical impedance spectroscopy (EIS) results indicated that the SrTiO3/Bi2S3 heterojunction reduces the rate of photogenerated electron–hole pair recombination and electron-transfer resistance than pure SrTiO3 and Bi2S3. The formation of SrTiO3/Bi2S3 heterojunction effectively separates the photogenerated charge carriers, which enhances the photocatalytic hydrogen production under UV light. The SrTiO3/Bi2S3 heterojunction shows superior photocatalytic hydrogen production than bare SrTiO3 and Bi2S3 due to the synergistic effect. The photocatalytic hydrogen production of SrTiO3/Bi2S3 (5%) gives 7.7 mmol g–1 within 180 min under UV irradiation.

High-order replica bands in monolayer FeSe/SrTiO3 revealed by polarization-dependent photoemission spectroscopy

The mechanism of the enhanced superconductivity in monolayer FeSe/SrTiO3 has been enthusiastically studied and debated over the past decade. One specific observation has been taken to be of central importance: the replica bands in the photoemission spectrum. Although suggestive of electron-phonon interaction in the material, the essence of these spectroscopic features remains highly controversial. In this work, we conduct angle-resolved photoemission spectroscopy measurements on monolayer FeSe/SrTiO3 using linearly polarized photons. This configuration enables unambiguous characterization of the valence electronic structure with a suppression of the spectral background. We consistently observe high-order replica bands derived from various Fe 3d bands, similar to those observed on bare SrTiO3. The intensity of the replica bands is unexpectedly high and different between dxy and dyz bands. Our results provide new insights on the electronic structure of this high-temperature superconductor and the physical origin of the photoemission replica bands.

Synthesis and Characterizations of Nitrogen (N) Doped Strontium Titanate (SrTiO₃) Nanoparticles for Enhanced Visible Light Driven Photocatalytic Degradation.

Highly crystalline bare and N-doped SrTiO₃ nanoparticles were effectively synthesized with strontium acetate, titanium isopropoxide, hexamethylenetetramine as precursor via citric acid assisted hydrothermal process followed by calcination. The hydrothermally synthesized bare and N-doped SrTiO₃ NPs possessed monodispersity throughout with particle size diameter 50±5 nm but because of annealing at 750 °C temperature the synthesized NPs got agglomerate which created rough surface and induces oxygen vacancy in the NPs. Introducing N3- ions impurity into SrTiO₃ lattice tailored the electronic band structure of SrTiO₃ and extends its absorption into the visible region. It would display the p-type conductivity and facilitate the photoinduced electron-hole pairs towards respective site which diminishes the chances of recombination of electron-hole pairs that enhances photocatalytic degradation reaction. The results showed MB degraded about ~88 in just 140 min and followed first order reaction kinetics with rate constant k = 0.01489 mint-1.

Enhanced tunability of two-dimensional electron gas on SrTiO3 through heterostructuring

Two-dimensional electron gases (2DEGs) on the SrTiO3 (STO) surface or in STO-based heterostructures have exhibited many intriguing phenomena, which are strongly dependent on the 2DEG-carrier density. We report that the tunability of the 2DEG-carrier density is significantly enhanced by adding a monolayer LaTiO3 (LTO) onto the STO. Ultraviolet (UV) irradiation induced maximum carrier density of the 2DEG in LTO/STO is increased by a factor of ~4 times, compared to that of the bare STO. By oxygen gas exposure, it becomes 10 times smaller than that of the bare STO. This enhanced tunability is attributed to the drastic surface property change of a polar LTO layer by UV irradiation and O2 exposure. This indicates that the 2DEG controllability in LTO/STO is more reliable than that on the bare STO driven by defects, such an oxygen vacancy.

Highly efficient SrTiO3/Ag2O n-p heterojunction photocatalysts: improved charge carrier separation and enhanced visible-light harvesting

Strontium titanate (SrTiO3) with perovskite structure has recently received significant attention in t he area of photocatalysis. However, challenges remain relating to its industrial applications; the high charge carrier recombination rate and low light-harvesting efficiency being the main two. Herein, a novel strategy based on fabrication of a typical n-p heterojunction has been proposed and the typical narrow-bandgap p-type semiconductor Ag2O was chosen to be coupled with SrTiO3 using a facile chemical precipitation method. The phase compositions, microstructures and optical properties of the prepared SrTiO3/Ag2O heterostructured photocatalysts have been systematically investigated with an x-ray diffractometer, scanning electron microscope, high resolution transmission electron microscope, x-ray photoelectron spectroscope and UV–vis spectrophotometer. The photocatalytic properties were evaluated through photodegradation of a common organic dye Rhodamine B (RhB). The results demonstrated that the heterostructured photocatalyst SrTiO3/Ag2O-0.15 outperformed pristine SrTiO3 and Ag2O. Specifically, the reaction rate of SrTiO3/Ag2O-0.15 is about 69 times and 4 times that of bare SrTiO3 and Ag2O respectively in photodegradation of RhB. The excellent photocatalytic performance was attributed to the synergetic effect between the improved visible-light harvesting efficiency and inhibited electron–hole recombination rate arising from the built-in electric field in a p-n heterojunction, as evidenced by the transient photocurrent and photoluminescence spectrum investigation. Furthermore, the excellent recyclability of the heterostructured photocatalyst was confirmed and holes were verified to be the major active species contributing to the overall degradation. Our findings demonstrate construction of p-n heterojunctions with narrow-bandgap semiconductors as a feasible avenue to promote overall photocatalytic efficiency, through simultaneously boosting charge-carrier separation and expanding photon-absorption range.

Fabrication of hierarchical SrTiO3@MoS2 heterostructure nanofibers as efficient and low-cost electrocatalysts for hydrogen-evolution reactions

The construction of low-cost, high-performance electrocatalysts instead of platinum catalysts is critical to solving the energy crisis. Here, using simple electrospinning and hydrothermal methods, new MoS2 nanosheets on SrTiO3 nanofibers (NFs) and 2D SrTiO3@MoS2 heterostructure NFs are synthesized. In addition, SrTiO3@MoS2 heterostructure NFs are compared with bare SrTiO3 NFs and MoS2 nanosheets. Importantly, the prepared SrTiO3@MoS2 heterostructure shows better hydrogen-evolution reaction performance than other MoS2-based electrocatalysts with an overpotential of 165 mV at 10 mA cm−2, a Tafel slope of 81.41 mV dec−1, and long-term electrochemical durability of 3000 cycles. Therefore, the present work strongly demonstrates the positive synergy between SrTiO3 NFs and layered MoS2, and also provides a strategy for preparing low-cost and high-activity water-decomposition electrocatalysts.

Enhanced photocatalytic activity of hydrothermally synthesised SrTiO3/rGO for gaseous toluene degradation in the air: modelling and process optimisation using response surface methodology

ABSTRACT In this study, the synthesised SrTiO3 was deposited on the graphene oxide (GO) by a simple hydrothermal method. Synthesised photocatalysts were used for photocatalytic degradation of gaseous toluene in a dynamic mode under UV irradiation. Characterisation of catalysts was performed by XRD, FE-SEM, UV-vis DRS, and FTIR. Results showed that the introduction of graphene increases the removal efficiency due to its high adsorption capacity and hydrophobic property. Process parameters’ (flow rate, toluene initial concentration, and relative humidity) effects on toluene removal efficiency and the interaction between them were investigated by Central composite design (CCD). Analysis of Variance (ANOVA) was used to evaluate the significance of the variables’ effects and the interaction between them. Maximum removal efficiency (RE) of 27.2 % and 32% were obtained by bare SrTiO3 and SrTiO3/rGO, respectively. The results revealed that the relative humidity and flow rate had significant negative effects on toluene RE over both catalysts, while concentration had a significant negative effect only on the RE over bare SrTiO3. Relative humidity was the most important factor that affects the RE on both photocatalysts.

Non-magnetic interfaces of LaAlO3/SrTiO3 made by on-axis sputter deposition and the contribution of SrTiO3 substrate

Abstract The magnetic properties of interfaces between LaAlO3/SrTiO3 are studied by on-axis sputter deposition at high oxygen pressure. The high pressure sputtering does not induce conductance at these interface, and without conductance, they should not be magnetic either. We find that a possible contribution of SrTiO3 can not be ruled out fully as the bare SrTiO3 substrate also shows a magnetic signal. All interfaces reported in literature grown by either PLD or MBE which are conducting, also have magnetism which arises from the onset of conductivity. If one is missing, the second does too as in the case reported here while SrTiO3 contributes substantially to the conductance of the interface.

Fabrication of Novel n-SrTiO3/p-BiOI Heterojunction for Degradation of Crystal Violet Under Simulated Solar Light Irradiation

Novel n-SrTiO3/p-BiOI heterojunction composites were successfully fabricated by loading SrTiO3 particles onto the surface of BiOI nanoflakes via a two-step method. The as-prepared samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FE-SEM), energy-disperse X-ray spectroscopy (EDS), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET), diffuse reflectance spectroscopy (DRS) and electrochemical measurements. The results show that the n-SrTiO3/p-BiOI heterojunction composites are composed of perovskite structure SrTiO3 and tetragonal phase BiOI. The composites exhibit excellent photocatalytic performance for the degradation of crystal violet (CV) solution under simulated solar light irradiation, which is superior to that of pristine BiOI and SrTiO3. The 30[Formula: see text]wt.%SrTiO3/BiOI composite is found to be the optimal composite, over which the dye degradation reaches 92.5% for 30[Formula: see text]min of photocatalysis. The photocatalytic activity of the 30[Formula: see text]wt.%SrTiO3/BiOI composite is found to be 3.94 times and 28.2 times higher than that of bare BiOI and SrTiO3, respectively. The reactive species trapping experiments suggest that [Formula: see text] and holes are the main active species responsible for the CV degradation. In addition, the electrochemical measurements elucidate the effective separation of photoinduced electron–hole pairs. Moreover, on the basis of experimental and theoretical results, a possible mechanism for the enhanced photocatalytic performance of the SrTiO3/BiOI heterojunction composites is also proposed.

SrTiO3 Nanoparticle/SnNb2O6 Nanosheet 0D/2D Heterojunctions with Enhanced Interfacial Charge Separation and Photocatalytic Hydrogen Evolution Activity

Exploration of high performance and stable metal-oxide-based hybrid photocatalysts for hydrogen evolution is highly desirable. In this work, novel SrTiO3 nanoparticles/SnNb2O6 nanosheets hybrid 0D/2D heterojunctions with an interfacial interaction were constructed by a facile two-step wet chemistry strategy. Different characterization techniques were adopted to investigate the microscopic structures and physicochemical properties of the as-prepared hybrid heterojunctions. The optimal weight percent of SrTiO3 loading is 20 wt%, generating the highest H2 evolution amount of 17.16 μmol, which are 298 and 2 times higher than that of bare SrTiO3 and SnNb2O6. It can be suggested that an interfacial interaction among SrTiO3 and SnNb2O6 could result in efficient charge separation and enhanced H2-generation activity, which was confirmed by photoelectrochemical analyses. This work implies that the construction of 0D/2D metal-oxide-based hybrid heterojunctions with an interfacial interaction is an effective way to f...

Improved charge separation and surface activation via boron-doped layered polyhedron SrTiO3 for co-catalyst free photocatalytic CO2 conversion

For efficient photocatalytic CO2 conversion to solar fuel, it is highly desired to enhance the solar-light absorption, photogenerated charge separation and surface active/catalytic performance of semiconductor photocatalysts. Herein, we have successfully prepared boron-doped layered polyhedron SrTiO3 (STO) by solid-state method using specific TiB2 precursor as boron and titanium resource. The prepared polyhedron STO is single-crystal structure with average diameter of ∼500nm and boron-doped STO exhibits overlapped-layer structure. The boron doping amount could be controlled using TiB2. It is shown that the amount optimized boron-doped layered polyhedron STO sample Exhibit 3-times enhanced co-catalyst free photocatalytic activity for CO2 conversion, compared to the bare STO nanoparticles. Notably, the improved photocatalytic performance could be attributed to the enhanced charge separation as confirmed by means of fluorescence emission spectra related to produced OH radicals, surface photovoltage responses and photoelectrochemical measurements; and the enhanced CO2 surface adsorption and catalytic performance of boron-doped SrTiO3 as verified by CO2-TPD and electrochemical CO2 reduction experiments. This work implies that boron-doped layered polyhedron SrTiO3 would display promising applications in the photocatalytic field of CO2 conversion to solar fuels.

Electronic Band Alignment at Complex Oxide Interfaces Measured by Scanning Photocurrent Microscopy

The band alignment at an Al2O3/SrTiO3 heterointerface forming a two-dimensional electron gas (2DEG) was investigated using scanning photocurrent microscopy (SPCM) in an electrolyte-gated environment. We used a focused UV laser source for above-the-bandgap illumination on the SrTiO3 layer, creating electron-hole pairs that contributed to the photocurrent through migration towards the metal electrodes. The polarity of the SPCM signals of a bare SrTiO3 device shows typical p-type behavior at zero gate bias, in which the photogenerated electrons are collected by the electrodes. In contrast, the SPCM polarity of 2DEG device indicates that the hole carriers were collected by the metal electrodes. Careful transport measurements revealed that the gate-dependent conductance of the 2DEG devices exhibits n-type switching behavior. More importantly, the SPCM signals in 2DEG devices demonstrated very unique gate-responses that cannot be found in conventional semiconducting devices, based on which we were able to perform detailed investigation into the electronic band alignment of the 2DEG devices and obtain the valence band offset at the heterointerface.