Ultraviolet Light Illumination Research Articles

Evaluation of photocatalytic properties of TiO2/g-C3N4 core-shell hybrid catalyst supported on Sr4Al14O25:eu,dy phosphor

TiO2/g-C3N4 hybrid compounds were supported as core-shell catalyst on Sr4Al14O25:Eu,Dy phosphor powder by a 2-step hydrothermal and solvothermal self-assembly method. Surface and chemical characterizations confirmed that the phosphor substrate and the hybrid catalysts co-existed as a multi-composite material. Where nano spherical TiO2 particles were dominant as core/shell catalyst. Diffuse reflectance spectra were shifted toward the visible light region (400 nm to 600 nm) in composites with g-C3N4 as shell-catalyst. X-ray photon spectroscopy (XPS) confirmed the chemical integrity and binding of g-C3N4 on phosphor/TiO2 material. When g-C3N4 was coated as shell-catalyst on phosphor/TiO2, superior photocatalytic performances of above 90% efficiency were obtained in comparison to where TiO2 was coated as shell-catalyst under both ultraviolet and visible light illumination. Thus, g-C3N4 is more active as shell-catalyst owing to its lower band gap of 2.7 eV than core TiO2 (3.2 eV).

Aluminium-doped Carbon Dots for the Simultaneous Selective Detection of Five Tetracycline Antibiotics.

In this paper, the aluminium-doped carbon dots (Al-CDs) were developed for simultaneous selective detection of five tetracycline antibiotics (TCs), including minocycline (MC), tetracycline (TC), oxytetracycline (OTC), doxycycline (DOC) and chlortetracycline (CTC). With the bright blue fluorescence, Al-CDs displayed excellent stability and showed no obvious fluorescence intensity changes under different ionic strength, acidic or alkaline environment, continuous ultraviolet light illumination, and even longtime storage at room temperature. As adding different antibiotics, the fluorescence of Al-CDs was strongly quenched by five TCs and showed no distinguished changes with the addition of other kinds of antibiotics. The presence of interferential metal ions, anions and small organic molecules imposed no effect on the simultaneous selective detection of five TCs. A good linear relationship was achieved for five TCs in the range of 0-100μM, and the limit of detection for MC, TC, OTC, DOC, and CTC were 13.91 (0-100μM), 15.54 (0-100μM), 14.26 (0-100μM), 13.48 (0-100μM) and 13.88nM (0-100μM), respectively. Moreover, Al-CDs was successfully used to the detection of five TCs in real samples with recovery ranging from 92.47% to 122.05%, confirming a bright future for the practical applications in the assays of foods, medicines, and environments.

Toward a better knowledge of Beethoven's creative process through the ink characterization: A non-invasive study of the sketchleaves held at the Civic Library in Bergamo (Italy)

Ludwig van Beethoven (1770–1827) used to record his ideas in sketchleaves and sketchbooks, where he collected preparatory materials before publishing his final work. These handwritten documents are rich in information. Nonetheless, as a consequence of the creative process, the annotations are much reworked by the composer itself, making them hard to interpret. This study aims, for the first time, at a non-invasive characterization of the inks used by Ludwig van Beethoven in his manuscripts. Distinguishing the inks used for the notes and the rewritten or modified parts would allow a better comprehension of his creative process. With this purpose, the manuscript BG0044 Piatti-Lochis PREIS.J1.9686, held at the Angelo Mai Civic Library of Bergamo (Italy), was investigated by exploiting portable imaging and spectroscopic techniques. The photographic documentation under Visible (VIS) and Ultraviolet light (UVIF) illumination, along with the Hyperspectral Imaging (HSI) in the spectral range 450 nm to 1000 nm were essential to identify the areas of interest for further analysis and provide a working hypothesis on the inks used by Beethoven. Afterwards, X-Ray Fluorescence (XRF) spectroscopy was employed to get an insight into the chemical composition of the inks. The foremost result revealed the presence of two different iron-based inks, used for the staves and the handwritten musical notations, respectively. The superimposed strokes observed among the staves on the same material composition led us to suppose that they have been applied immediately to the paper or in a limited time during which the same ink recipe was maintained. Hence, it seems that the composer made changes almost at the same time as he wrote the first version. These results represent the first scientific evidence to endorse the hypothesis of a rapid change of mind in his writing process.

Photoconductivity in self-assembled CuO thin films

Self-assembly is the most promising low-cost and high-throughput methodology for nanofabrication. This paper reports the optimization of a self-assembly process at room temperature for the growth of copper oxide (CuO) based nanostructures over a copper substrate using aqueous potassium hydroxide (KOH) solution as the oxidizing agent. The monoclinic phase of CuO nanostructures grown over the copper substrate was confirmed from the X-ray diffraction (XRD) and micro-Raman analysis. The overall chemical composition of nanostructures was confirmed to be that of CuO from its oxidation state using X-ray photoelectron spectroscopy (XPS). Photodetectors were engineered with the structure Cu/CuO/Ag. The photodetectors exhibited a response to both ultraviolet and visible light illumination. The optimized Cu/CuO/Ag structure exhibits a responsivity of ~ 1.65 µA/W, with an ON:OFF ratio of ~ 69 under a bias voltage of 0.01 V. The temporal dependence of photo-response for the optimized photodetector displayed the persistent nature of photoconduction indicating a delay in charge carrier recombination which could potentially be exploited for photovoltaic applications.

Gallium oxide nanocrystals for self-powered deep ultraviolet photodetectors

Zero-dimensional colloidal nanocrystals (NCs) of gamma-phased gallium oxide (γ-Ga2O3) were successfully synthesized using the sol-gel method, resulting in nanocrystals with high crystallinity. Heterojunction photodetectors were then constructed by employing spin-coating technology to deposit γ-Ga2O3 NCs film of varying thicknesses onto p-type GaN substrates. The resulting devices demonstrated self-power capability through a photovoltaic effect when exposed to ultraviolet light illumination. Notably, a device with a 300 nm thick active layer, annealed in 400 °C, exhibited a responsivity of 6.7 × 10–3 A W–1, a detectivity of 3.10 × 1011 Jones, and an external quantum efficiency of 3.2 % under 254 nm light illumination at 0.16 mW cm–2, all without the need for an external power supply. These findings suggest promising practical applications for such photodetectors in single-point imaging systems. This study presents a straightforward and viable approach for developing high-performance and self-powered ultraviolet photodetectors based on zero-dimensional γ-Ga2O3 NCs, thereby opening up possibilities for various photonic systems and applications that do not rely on an external power supply.

Thermochromic Cs2NaInCl6: Sb3+/Ln3+ (Ln = Er, Dy, Tb, Ho) phosphors for multifunctional applications

The intrinsic challenge to thermally responsive photoluminescent materials is pertaining to the limited thermal stability and reproducibility. Most prevailing photoluminescent agents suffer from constraints imposed by their frail chemical structure, rendering them fail to work at elevated temperatures for a long time. This inherent limitation curtails their utility within domains in anti-counterfeiting and encoded information storage. Herein, a series of double perovskite Cs2NaInCl6: Sb3+/Ln3+ (Ln = Er, Dy, Tb, Ho) phosphors were synthesized using the high-temperature hydrothermal method. Upon ultraviolet light illumination, the blue emission band of self-trapped excitons (STEs) and intrinsic emissions of Ln3+ are observed. In light of the variations in thermal quenching levels of the two emission centers and the effect of temperature on the lifetime of Ln3+, multi-mode thermometers with superior sensitivity are established. Moreover, they also can be used in anti-counterfeiting and encoding information storage, relying on the significant temperature-dependent color variation, excellent thermal stability and repeatability. The unique thermochromic properties and satisfactory stability of Cs2NaInCl6: Sb3+/Ln3+ (Ln = Er, Dy, Tb, Ho) phosphors bring forward a new concept of developing multi-mode thermometers and reliable information encryption systems with the application of thermochromic materials.

Organofunctionalization of silica from rice husk ash with ESIPT dyes

Excited-state intramolecular proton transfer (ESIPT) dyes were immobilized on amorphous silica obtained from rice husk ash through surface modification methodology. The silanol groups present on the surface of silica were first functionalized with isocyanate groups to be reacted with ESIPT dyes. Scanning electron microscopy, infrared spectroscopy, thermogravimetric, nitrogen adsorption/desorption, powder X-ray diffraction, and solid-state fluorescence emission spectroscopy analysis have been carried out to characterize the materials. The synthesized silica-based fluorescent materials were used as latent fingerprint developer powders present on glass surfaces. The results showed that latent fingerprints were revealed with high contrast under ultraviolet light illumination.

The enhanced responsivity and response speed of SnO2 visible-blind transparent photodetectors via the SiO2 passivation layer.

Recently, transparent ultraviolet (UV) photodetectors have gained wide attention for their giant potential in integrated transparent electronics applications. SnO2 films as a common candidate for visible-blind transparent ultraviolet photodetectors have attracted increasing attention. In this work, high-performance visible-blind transparent UV photodetectors based on SnO2 thin film and a SiO2 passivation layer were successfully synthesized by the sol-gel spin coating method for the first time. The obtained SnO2/SiO2 hybrid device has a transmittance of nearly 80% in the visible band at 400-700 nm and demonstrates a high responsivity of 769 mA W-1 and a detection sensitivity of 1.24 × 1014 Jones under UV light illumination. The UV-C/UV-A rejection ratio is greater than 106, indicating that the device has good photo-selectivity. In addition, after the introdution of the SiO2 layer, the response speed is 2 times higher than that of pure SnO2. The presence of the SiO2 layer reduces the exposed area of SnO2, passivates the oxygen vacancies on the surface of SnO2 and inhibits the surface chemical adsorption. The above results provide a new perspective for improving the performance of SnO2 thin film for visible-blind transparent ultraviolet photodetectors.

Polar topological superdomain arrays in PMN-PT crystals engineered via a voltage-free method

Domain engineering is an active field of research that aims to enhance the functional properties of ferroelectric materials for various applications. This work presents a voltage-free method for fabricating topological superdomain arrays in 0.72Pb(Mg1/3Nb2/3)O3-0.28PbTiO3 (PMN-28PT) crystals. During the cooling process from high-temperature paraelectric phase to room temperature ferroelectric phase, the out-of-plane polarization of PMN-28PT crystals in contact with aluminum can be fully regulated downward, attributed to the difference in the work function of aluminum and PMN-28PT. In conjunction further with photolithography and ultraviolet light illumination, it is easy to obtain periodic strip domain structures with alternating up and down polarization. Moreover, this method can also control in-plane polarization, resulting in a large-scale central divergent/convergent topological superdomain array. These findings provide insights into ferroelectric domain engineering and have implications for the development of electromechanical, piezoelectronic, and photonic devices.

Synthesis of a water-stable CsPbBr3 perovskite for selective detection of mercury ion in water.

By using the method of low-temperature crystallization, CsPbBr3 perovskite nanocrystals (PNCs) coated with trifluoroacetyl lysine (Tfa-Lys) and oleamine (Olam) were synthesized in aqueous solution. The structure of the CsPbBr3 PNCs was characterized by many methods, such as ultraviolet (UV)-visible absorption spectrophotometer, fluorescence spectrophotometer, transmission electron microscopy (TEM), and X-ray diffraction (XRD) pattern. The fluorescence emission of the CsPbBr3 PNCs is stable in water for about 1 day at room temperature. It was also found that the fluorescence of the PNCs could be obviously and selectively quenched after the addition of mercury ion (Hg2+ ), allowing a visual detection of Hg2+ by the naked eye under UV light illumination. The fluorescence quenching rate (I0 /I) has a good linear relationship with the addition of Hg2+ in the concentration range 0.075 to 1.5 mg/L, with a correlation coefficient (R2 ) of 0.997, and limit of detection of 0.046 mg/L. The fluorescence quenching mechanism of the PNCs was determined by the fluorescence lifetime and X-ray photoelectron spectroscopy (XPS) of the PNCs. Overall, the synthesis method for CsPbBr3 PNCs is simple and rapid, and the as-prepared PNCs are stable in water that could be conveniently used for selective detection of Hg2+ in the water environment.

Saccharide-Derived Zinc Oxide Nanoparticles with High Photocatalytic Activity for Water Decontamination and Sanitation

Zinc oxide nanoparticles (ZnO NPs) with a high photocatalytic performance were prepared by using the aerobic combustion of saccharides such as glucose, fructose, dextrin, and starch with zinc nitrate. The ZnO NPs were characterized by using transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray scattering spectroscopy (EDX), X-ray powder diffraction (XRPD), and UV-vis spectroscopy. The TEM images revealed that the ZnO NPs have sizes ranging from ~20 to 35 nm with a bandgap of ~3.32 eV. The XRPD pattern revealed the hexagonal wurtzite crystalline structure of the ZnO NPs. The photocatalytic properties of the ZnO NPs were studied by the photocatalytic degradation of methyl orange (MO) in deionized water (DIW) and simulated fresh drinking water (FDW) under ultraviolet light (UV-B) and sunlight illumination. The terephthalic acid photoluminescence technique was also used to study the generation of a hydroxyl radical (•OH) by ZnO NPs. The saccharide-derived ZnO NPs exhibited higher photocatalytic activity than the nonsaccharide-derived ZnO NPs. Varying the type of saccharides used during the calcination had some effect on the degree of the catalytic enhancement.

Ultrahigh UV Responsivity Quasi-Two-Dimensional BixSn1-xO2 Films Achieved through Surface Reaction.

In this study, quasi-two-dimensional BixSn1-xO2 (BTO) thin films were fabricated using a liquid metal transfer method. The ultraviolet (UV) photodetector based on BTO thin films was constructed, and the ultrahigh responsivity of 589 A/W was observed at 300 nm UV light illumination. Interestingly, by dropping ethanol during light-off period, the recovery time induced by the persistent photoconductivity (PPC) effect is reduced from 1.65 × 103 s to 5.71 s. Furthermore, the recovery time can also be reduced by dropping methanol, propylene glycol, NaNO2, and Na2SO3 after light termination. The working mechanisms are attributed to the rapid consumption of holes stored in BTO thin films by reaction with those solutions. This work demonstrates that the BTO thin films have potential applications in high-performance UV detectors and present an innovation route to weaken the PPC effects in semiconductors by introducing chemical liquids on their surface.

A computer vision approach to improve maintenance automation for thermal power plants lubrication systems

PurposeLubricating oil leakage is a common issue in thermal power plant operation sites, requiring prompt equipment maintenance. The real-time detection of leakage occurrences could avoid disruptive consequences caused by the lack of timely maintenance. Currently, inspection operations are mostly carried out manually, resulting in time-consuming processes prone to health and safety hazards. To overcome such issues, this paper proposes a machine vision-based inspection system aimed at automating the oil leakage detection for improving the maintenance procedures.Design/methodology/approachThe approach aims at developing a novel modular-structured automatic inspection system. The image acquisition module collects digital images along a predefined inspection path using a dual-light (i.e. ultraviolet and blue light) illumination system, deploying the fluorescence of the lubricating oil while suppressing unwanted background noise. The image processing module is designed to detect the oil leakage within the digital images minimizing detection errors. A case study is reported to validate the industrial suitability of the proposed inspection system.FindingsOn-site experimental results demonstrate the capabilities to complete the automatic inspection procedures of the tested industrial equipment by achieving an oil leakage detection accuracy up to 99.13%.Practical implicationsThe proposed inspection system can be adopted in industrial context to detect lubricant leakage ensuring the equipment and the operators safety.Originality/valueThe proposed inspection system adopts a computer vision approach, which deploys the combination of two separate sources of light, to boost the detection capabilities, enabling the application for a variety of particularly hard-to-inspect industrial contexts.

The Surface Behavior of ZnO Films Prepared at Room Temperature

The surface behavior of ZnO-based films can be modulated via the postannealing and ultraviolet (UV) illumination of different strengths and durations, respectively. The present results could provide the basis for modulating their microstructures with respect to the grain-size distribution and photocatalytic behavior, and act as a potential guide in the field of wide-bandgap semiconducting oxides. ZnO films were prepared at room temperature onto Corning-1737 glass substrates by applying radio-frequency magnetron sputtering without supplying an oxygen source. With the purpose of obtaining modulational grain microstructures, the as-prepared ZnO films (Z0) were treated via a postannealing modification in a vacuum furnace at 300 °C for 30 min after deposition (Z300), accompanied by adjustable internal stress. The contact angle (CA) value of the ZnO films was reduced from 95° to 68°, owing to the different grain microstructure accompanied by a change in the size variation. In addition, UV light with different illumination strengths could be used to improve the hydrophilicity, which varied from a hydrophobic status to a superhydrophilic status due to the desirable surface characteristics of its photocatalytic action. In addition, the photocatalytic activity of the ZnO films exhibited an effectual photodegradation of methylene blue (MB) under UV illumination, with a chemical reaction constant of 2.93 × 10−3 min−1. In this present work, we demonstrated that the CA value of the ZnO films not only caused a change from a hydrophobic to hydrophilic status, accompanied by a change in grain size combined with internal stress, but also, induced by the UV light illumination, was combined with photocatalytic activity simultaneously. On the other hand, an enhanced surface plasmonic resonance was observed, which was due to couple oscillations between the electrons and photons and was generated from the interface by using a flat, continuous Pt capping nanolayer. This designed structure may also be considered as a Pt electrode pattern onto ZnO (metal Pt/ceramic ZnO) for multifunctional, heterostructured sensors and devices in the near future.

Dual-mode security authentication of SrAl2 O4 :Eu,Dy phosphor encapsulated in electrospun cellulose acetate nanofibrous films.

Photochromic inks have been an attractive authentication strategy to improve the anti-counterfeiting efficiency of commercial products. However, recent reports have showed significant disadvantages with photochromic inks, including poor durability and high cost. In this context, we develop novel photochromic nanofibers for advanced anti-counterfeiting applications. Lanthanide-doped strontium aluminate (LdSA) nanoparticles (NPs) were prepared and immobilized into electrospun cellulose acetate nanofibers (CANF). Authentication materials immobilized with inorganic photochromic agent can warranty durability and photostability. Therefore, the ultraviolet-stimulated photochromism of LdSA-encapsulated cellulose acetate nanofibers (LdSA@CANF) demonstrated high reversibility and photostability. A broad range of cellulose acetate nanofibers with unique emission characteristics were developed when applying different ratios of LdSA NPs. LdSA@CANF appeared colorless under visible daylight, whereas a green emission was monitored under UV-illumination. The shape and chemical content of the photochromic fibrous films were examined by various analytical techniques. The mechanical characteristics of LdSA@CANF-coated paper were investigated. The emission wavelength was detected at 514 nm to designate green color, whereas the excitation wavelength was detected at 369 nm to indicate transparency. The prepared cellulose acetate nanofibrous film can be described as an efficient strategy for anti-counterfeiting of commercialized items.

Effect of Ultraviolet Illumination on the Fixation of Silver Ions on Zinc Oxide Films and Their Photocatalytic Efficiency

This study focuses on the fabrication and characterization of nanostructured zinc oxide films deposited on glass substrates using sol–gel dip-coating methods. The thin films are functionalized with silver ions at various Ag+ concentrations (10−2, 10−3, 10−4 M) through room temperature ion fixation process with and without ultraviolet (UV) illumination. Physicochemical characterization techniques, such as employing Scanning Electron Microscopy with Energy-dispersive X-ray spectroscopy (SEM-EDX), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Ultraviolet–Visible Spectroscopy and Electron Paramagnetic Resonance (EPR) techniques. The SEM-EDX and XRD confirmed a characteristic ganglia-like structure with a hexagonal crystalline structure. The photocatalytic performance and available surface area of the pure and Ag films are investigated in the removal of methylene blue dye under UV and visible light illumination and in darkness. It is observed that the photocatalytic activity increases proportionally to the Ag+ ion concentration: ZnO < Ag(10−4 M)/ZnO, < Ag(10−3 M)/ZnO < Ag(10−2 M)/ZnO. Moreover, the catalysts modified under UV illumination during the fixation treatment (Ag-UV/ZnO) exhibited a higher photocatalytic efficiency and degraded the dye in comparison with those without a light source (Ag/ZnO). The experimental results are confirmed using total organic carbon (TOC) analysis. The optimal silver concentration (10−2 M) is established, which shows the highest photocatalytic efficiency (in both cases of ion fixation treatment). The results can be used as a guideline for the development of co-catalyst-functionalized semiconductor photocatalysts.

A Cu-Modified Photocatalyst Composite: Synthesis, Characterization and Photocatalysis

To obtain highly efficient photocatalysts, we successfully prepared the GO/ZnO/CdS/Cu2S composite that possesses superior photocatalytic degradation performance via a three-step solvothermal process. A series of characterization techniques were used to verify the composition and performance of prepared samples, such as X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), scanning electron microscopy (SEM), Raman spectra, photoluminescence (PL) spectroscopy and so on. SEM reveals that copper ions are supported on the surface of CdS to form active sites for photocatalysis. Under the irradiation of ultraviolet (UV) and visible light, GO/ZnO/CdS/Cu2S photocatalyst exhibited relatively excellent photocatalytic degradation efficiency of methylene blue (MB), with 100% (80 min) and 95% (30 min), respectively. Compared with pure ZnO ([Formula: see text]) under the illumination of UV light, the kinetic constant of GO/ZnO/CdS/Cu2S catalyst is up to [Formula: see text], and as for visible light illumination, up to [Formula: see text], showing relatively excellent visible-light-induced photocatalytic activity. Besides, under UV and visible light, after three cycles of photodegradation, GO/ZnO/CdS/Cu2S still maintains the degradation efficiency of 78.3% and 74.8%, respectively, indicating that it has good stability. This work might inspire a new perspective that introduces the surface reaction sites (Cu2S) in the design of other graphene oxide/mental oxide-based heterojunctions for environmental purification.

A self-powered ultraviolet photodetector based on TiO2 nanoarrays and poly(3,4-ethylenedioxyselenophene) with the enhanced performance by pyro-phototronic effect

Pyro-phototronic effect plays an important role in improving the photodetection performance of ultraviolet (UV) photodetectors (PDs). Here, a novel pyro-phototronic effect between TiO2 nanoarrays (TiO2 NRs) and the conducting polymer poly(3,4-ethylenedioxy selenophene) (PEDOS) is applied to fabricate a self-powered UV PD with the enhanced photodetection ability. The self-powered p-n heterojunction UV PD is fabricated by a face-to-face hybrid of acid (HCl and H2SO4)-treated TiO2 NRs with PEDOS. Interestingly, a pyro-phototronic effect is found between TiO2 NRs/FTO and PEDOS/FTO, and the acid treatment of TiO2 NRs can dramatically enhance the pyro-phototronic effect. H2SO4 treatment can improve the p-n heterojunction, while HCl treatment can increase carrier concentration due to the introduction of surface oxygen vacancies on the surface of TiO2 NRs. Under UV light illumination and 0 bias voltage, the rise time (Trise) and fall time (Tfall) of UV PD from the face-to-face hybrid of PEDOS/FTO with TiO2(HCl)/FTO are 0.080 s and 0.079 s, while the responsivity (R) and detectivity (D*) are 58.706 mA/W and 3.627 × 1011 Jones, respectively. The face-to-face fabrication of UV PDs and the matching of the energy levels between PEDOS and TiO2 NRs cause the pyro-phototronic effect due to temperature change and pyroelectric effect of TiO2 NRs under the UV light illumination. This work gives a new idea to generate pyro-phototronic effect between TiO2 NRs and conducting polymers for application in UV PDs field.

Reflection transformation calibration for mirror-assisted multi-view digital image correlation system using fluorescent speckle patterns

Mirror-assisted multi-view digital image correlation (MV-DIC) is a simple-to-implement DIC technique for panoramic kinematic field measurements of regular-sized specimens. In the practical implementation of mirror-assisted MV-DIC, accurate reflection transformation calibration of the planar mirrors is considered as a pivotal step. In this work, we propose to use fluorescent speckle patterns fabricated on the mirrors to calibrate their reflection transformation matrices, which can fully utilize the camera’s spatial resolution and simplify the calibration processes. The fluorescent speckle patterns on the mirrors do not interfere with the virtual object surfaces using a regular blue-light stereo-DIC system. However, under the illumination of ultraviolet light, the fluorescent speckle patterns can be captured and used to calibrate the position and orientation of the planar mirrors. The practicality and efficacy of the fluorescent speckle pattern-based calibration method are validated by profile measurement and translation tests, and an application in a four-point bending experiment is also demonstrated.

Topotactic conversion synthesis of Ta4+-doped TaO@C and its enhanced photocatalytic and lithium-ion battery performance

Carbon coated highly crystalline tantalum oxide (TaO@C) nanoparticles with self-doping Ta4+ and lattice oxygen were successfully prepared by via a topotactic conversion strategy by annealing polydopamine-coated (NH4)2Ta2O3F6 mesocrystals. TaO@C sample exhibits not only satisfactory photocatalytic performance on methylene blue (MB) degradation with a efficiency of 57.66% and 31.81% under ultraviolet and visible light illumination for 3 h, but also superior lithium storage properties with high reversible capacity, high rate capability (140 mAh g−1 at 1250 mA g−1) and outstanding cyclic stability (∼109 mAh g−1 at 1250 mA g−1 current density after 900 cycles with 0.01% capacity varying per cycle capacity retention)). It is primarily attributed to the synergistic effect among large surface area (42.61 m2·g−1), fine particle size (<60 nm), core-shell structure with tight carbon coating and porous structure, and defects, leading to excellent electronic conductivity and lower bandgap energy. Furthermore, surface pseudocapacitive makes great contribution on good rate capability.