Light Region Research Articles

Preparation and properties of GdPO4:Dy3+ phosphors and ceramics with high thermal stability

In this work, Gd1-xPO4:xDy3+ powders were synthesized by calcining the mixed raw materials at 1273 K and the optimal doping concentration was determined. Then the optimized composition powders were fabricated as ceramics after granulation, pressing and sintering. Meanwhile, the luminescent properties of the phosphors and ceramics, especially the thermal stability, were discussed. The results revealed that Gd1-xPO4:xDy3+ exhibited two strong emission peaks of blue light and yellow light under the excitation of 349 nm, ascribed to the energy level transition from 4F9/2 to 6H15/2 and 6H13/2 of the electrons of Dy3+, and the color coordinates were located in the white light region. The optimal doping concentration of Dy3+ was found as 0.1, and the electronic dipole-dipole interaction contributed to the concentration quenching. It was noted that the phosphors had good thermal stability. Specifically, the thermal stability was further improved after the ceramics was formed and the relative intensity between the blue and yellow changed the opposite, indicating different occupation sites of Dy3+.

Magnetic Chitosan/ZrO2 Composites for Vanadium(V) Adsorption while Concurrently being Transformed to a Dual Functional Catalyst.

Spent adsorbents for recycling as catalysts have drawn considerable attention due to their environmentally benign chemistry properties. However, traditional thermocatalytic strategies limit their applications. Here, we developed an enhanced photocatalytic strategy to expand the range of their applications. A magnetic chitosan/ZrO2 composites (MZT) for V(V) adsorption, which were prepared using chitosan, ZrO2 and Fe3O4 by one-pot synthesis. The spent MZT as a catalyst was used to synthesize 2-phenyl-1H-benzo[d]imidazole, yielding up to 89.7 %. It also was implemented to photocatalysis reactions for recycle. The discolored rates of rhodamine B (RhB) were 72.3 % and 97.4 % by new and spent MZT, respectively. The new and spent MZT showed the forbidden bands were 251 nm and 561 nm, respectively. The result displayed spent MZT red shifted to the cyan light region. The mechanism of catalysis also has been studied in detail.

Effect of structural evolution and orientation behavior on optical properties of iodine-dyed PVA film during uniaxial stretching

In the process of preparing polarizing film, based on the research on the influence of the initial condensed structure of Poly (vinyl alcohol) (PVA) film on the dyeing and stretching process, the connection between the structure and performance of polarizing film is established, which is more conducive to understanding the post-processing process of solution casting molding of optical grade PVA film and the optimization of subsequent dyeing and stretching process. In this paper, PVA film with an appropriate swelling degree were selected for dyeing treatment, and the evolution of the condensed structure during stretching was studied in detail. The work also examined the formation and orientation of PVA-iodine complexes and the feedback effect of complex formation on the structural evolution of the film, with the goal of establishing the relationship between stretching ratio, structure, and performance of the polarizing film. The results show that the dyeing process inhibits the recrystallization of the PVA film during uniaxial stretching. However, the PVA-iodine complexes formed act as "anchors" to stabilize the oriented microfiber network, reducing the critical strains (εw and εs) required for the PVA film to enter the strain-hardening zone. Furthermore, as strain increases, the content of polyiodide ions and PVA-iodine complexes in the dyed PVA film also increases, especially making the formation of long iodide chains (I5−) and PVA-I5− complex more sensitive. Additionally, with increasing strain, both the transmittance and degree of polarization of the dyed PVA film improve, reaching optimal values in the strong strain-hardening zone (>εs). This indicates that εs is the minimum critical strain required to ensure optimal polarization performance of the film in the visible light region.

Tunable broadband luminescence of the novel Sn2+ doped oxyfluoride glass and glass-ceramics for W-LEDs

The demand for white-light luminescent materials for the white-light-emitting diodes (W-LEDs) field has been growing in modern life. In this work, a series of Sn2+ and Mn2+ ions co-doped highly transparent white-light emitting oxyfluoride glasses (precursor glass, PG) and Sr2LuF7 glass-ceramics (GC) were successfully prepared by the melt-quenching technique. Their luminescent and structural properties were investigated by the transmission spectra, excitation and emission spectra at different temperatures (300-500 K), luminescent decay curves, XRD, and TEM characterizations. Upon excitation with ultraviolet (UV) light, tunable broadband blue-white light emissions of Sn2+ were obtained by adjusting the concentration of Sn2+ ions. A conspicuous energy transfer process from Sn2+ to Mn2+ was observed in Sn2+/Mn2+ co-doped samples. Tunable broadband luminescence between blue-white light and orange-red light regions and nearly pink-white light emission was realized by varying Mn2+ concentration. Furthermore, compared to PG samples, the emissions were enhanced in GC samples due to the crystallization of Sr2LuF7 nanocrystals. Excellent thermal stability was also performed in these Sn2+ doped PG and GC samples with a recovering value of 96 % and 98.8 %, respectively. Simultaneously, Sn2+ doped PG and GC samples also own good optical thermal sensitivities with an SA value of 2.28 % and 2.47 % K-1, respectively. Our results indicate that these Sn2+/Mn2+ co-doped PG and GC may serve as tunable light sources under UV excitation and have prospects on the ratiometric optical thermometry fields.

Synthesis, characterization, and double shielding performance for ultraviolet and short-wave blue light of ceria-based materials

In order to extend the photo-shielding range of ceria from the ultraviolet (UV) region (≤400 nm) to the high-energy short-wave blue light (BL) region (400–450 nm), three groups of ceria-based materials, including ceria nanoparticles (nano-CeO2), cerium-oxygen-sulfur (Ce-O-S) composites and samarium-cerium-oxygen-sulfur (Sm-Ce-O-S) composites, were prepared from the perspectives of improving the preparation method, non-metal doping and metal/non-metal co-doping. Although the three groups of as-prepared samples have similar phase composition, morphology and pore structure, the Sm-Ce-O-S composites show remarkable double shielding performance for UV light and short-wave BL. Compared with nano-CeO2 and Ce-O-S composites, Sm-Ce-O-S composites that retains the characteristics of n-type semiconductor exhibits a greater degree of lattice distortion, higher concentrations of Ce3+ (41.17 %) and oxygen vacancy (77.29 %), and narrower band gap (2.71 eV). Through the comparison of the three groups of samples, the order of modification degree from high to low is as follows: metal/non-metal co-doping > non-metal doping > improving the preparation method. This paper provides experimental and theoretical support for breaking through the bottleneck of ceria in the fields of UV shielding agents and catalysts.

Novel Tm3+/Dy3+ co-doped CaMoO4 transparent glass-ceramic phosphor for white LED applications

To develop new inorganic luminescent materials, a set of Dy3+/Tm3+ co-doped molybdate precursor glasses (PGs) were manufactured using the conventional melting method, and a novel CaMoO4 transparent fluorescent glass-ceramic (GC700-2 h) was achieved via controlled crystallization of PG at 700 ℃ for 2 h. The luminescent color of the glass phosphor was facilely modulated by varying the doping levels of Dy3+ and Tm3+. The glass phosphor with optimal doping concentration of 0.6Dy3+ and 0.6Tm3+ exhibits a color coordinate of (0.3334, 0.3107). Compared with PG, the luminous intensity and quantum yield of GC700-2 h sample is obviously increased, and GC720-2 h sample displays the color coordinate (0.3292, 0.2852), belonging to the standard white light region. Moreover, GC720-2 h sample possesses good thermal stability in fluorescence property. The white LED lamp encapsulated with GC720-2 h exhibits color temperature of 7564 K and color rendering index of 75.3. These results clearly show that the 0.6Dy3+/0.6Tm3+ co-doped glass and CaMoO4 glass-ceramic could be used as potential candidate material in the field of white light-emitting diodes.

Comparative characterizations of plant and mineral dye as potential photosensitizer in Dye-Sensitized Solar Cell

The advent of dye-sensitized solar cells (DSSC) has expansively seen more studies as an alternative to silicon-based and thin-film solar cells due to their simple structure and relatively low production cost. In dye-sensitized solar cells, the dye is one of the major components for high power conversion efficiencies. The extracted dyes were characterized by powder x-ray diffraction, x-ray fluorescence, Scanning electron microscopy, UV-visible spectroscopy, and Gas Chromatography-Mass spectrometry analysis. The structure of the mineral dye contains constituents that enhance better absorption of solar radiation for use in a Dye-Sensitized Solar Cell (DSSC). The calcium and iron content of the mineral dye studied as revealed by the mineralogical analysis done using the powder x-ray diffraction (XRD) and the x-ray fluorescence (XRF) suggest this. These metals serve as bounding complexes to other organic components in the dye, like in the case of Ruthenium complexes dye for efficient absorption of solar radiation, especially in the visible light region. The functional groups present in the dye also confirm what favors good absorption of solar radiation for DSSC application. The Organic chemical compositions present in the mineral dye which were obtained by the Gas Chromatography-Mass spectrometry analysis also confirm the functional groups of carbonyl, Amine, and hydroxyl revealed by FTIR, which were responsible for solar radiation absorption. There are strong absorption narrow bands in the visible region with peaks at around 424 nm (2.903 a.u) and 486 nm (2.973 a.u). Optical band gaps of 1.66 eV and 2.27 eV for the mineral dye and plant dye respectively, were obtained. The properties of the dyes studied give potential substitutes to the relatively expensive ruthenium-based dyes for use in DSSC fabrication.

Insight into the Structural and Performance Correlation of Photocatalytic TiO2/Cu Composite Films Prepared by Magnetron Sputtering Method

Photocatalysis technology, as an efficient and safe environmentally friendly purification technique, has garnered significant attention and interest. Traditional TiO2 photocatalytic materials still face limitations in practical applications, hindering their widespread adoption. The research prepared TiO2/Cu films with different Cu contents using a magnetron sputtering multi-target co-deposition technique. The incorporation of Cu significantly enhances the antibacterial properties and visible light response of the films. The effects of different Cu contents on the microstructure, surface morphology, wettability, antibacterial properties, and visible light response of the films were investigated using an X-ray diffractometer, X-ray photoelectron spectrometer, field emission scanning electron microscope, confocal laser scanning microscope, Ultraviolet–visible spectrophotometer, and contact angle goniometer. The results showed that the prepared TiO2/Cu films were mainly composed of the rutile TiO2 phase and face-center cubic Cu phase. The introduction of Cu affected the crystal orientation of TiO2 and refined the grain size of the films. With the increase in Cu content, the surface roughness of the films first decreased and then increased. The water contact angle of the films first increased and then decreased, and the film exhibited optimal hydrophobicity when the Cu target power was 10 W. The TiO2/Cu films showed good antibacterial properties against Escherichia coli and Staphylococcus aureus. The introduction of Cu shifted the absorption edge of the films to the red region, significantly narrowed the band gap width to 2.5 eV, and broadened the light response range of the films to the visible light region.

The stability, electronic and optical properties of nonmetal doped g-GaN: A first-principles calculation

Doping is an effective strategy to modulate the electronic performance of materials by forming new chemical bonds and relaxing the neighboring bonds, which may change catalytic performance of materials. Herein, we demonstrate the effects of a series of nonmetal (NM) dopants on the electronic properties and photocatalytic activity of g-GaN monolayer using first-principle calculations. NM dopants prefer to substitute N atom under Ga-rich condition. C, O and F doped specimens are highly stable under both Ga-rich and N-rich conditions. NM dopants induce the generation of impurity levels, contributing to reduce the electronic transition energies. S, Se and Te doped specimens increase by about 11, 8 and 4 times for absorption intensity in the region of visible light, respectively. Remarkably, S, Cl, Se, Br, Te and I dopants can effectively decrease the recombination rate of photogenerated electrons and holes of the g-GaN in photocatalytic reaction. H, B, C Si, P and As doped system can induce more active sites. Remarkably, halogen dopants could increase the both redox and reduction ability of g-GaN monolayer. Thus, NM dopants can effectively tune redox potential of g-GaN monolayer and improve its photocatalytic performance.

Analysis of spectroscopic characteristics of Sm3+ ions doped gallium silicate glasses for orange-red LEDs

In this work, a variety of Sm3+ ions doped gallium silicate glasses have been made using the conventional melt quenching procedure, and characterized by X-ray diffraction, absorption spectrum, fluorescence spectrum, fluorescence decay curves, respectively. The density of the glass increases with the increase of the concentration of Sm3+ ions, and XRD shows that the samples are all amorphous glasses. Absorption spectra were used to determine the J-O intensity parameters (Ωλ, λ = 2, 4, 6), as well as the radiation transition probability(A), fluorescence branching ratio(βr), and radiation lifetime(τr) of Sm3+ ions at the 4G5/2 energy level. Under 403 nm excitation, the emission spectra show obvious emission peaks at 602 nm and 649 nm, corresponding to 4G5/2 → 6H7/2 and 4G5/2 → 6H9/2 transitions respectively. The B3 glass sample has the largest emission cross section(σem) at the 4G5/2 → 6H7/2 transition, with σem = 11.40 × 10−22 cm2. The color coordinates, color purity and color temperature values of all samples were calculated. The color purity of all samples varied in the range of 96.20%–99.14 %, with the relevant samples separating in the orange-red light region. The experimental results indicate that the glass samples have a potential application prospect in the field of orange-red LEDs.

Graphene with suitable-size nitrogen-doped cavity being an excellent photocatalyst for proton-coupled electron transfer in water splitting

Aiming to attain porous carbon nitride photocatalysts with high specific surface area, abundant active sites, broad absorption range and effective electron-hole separation, we remove carbon rings from graphene and replace all the edge carbon atoms of the cavity with nitrogen atoms. The accurate electronic structures and exciton properties of the proposed materials are revealed by the ab initio many-body Green's function theory. Computational results show that the absorption of the designed materials can cover both the visible and the near-infrared light region. The exciton binding energies of the materials are one order of magnitude lower than those of the typical two-dimensional photocatalyst graphitic carbon nitride. Due to the formation of hydrogen bonds between pyridinic nitrogen atoms and water molecules during water splitting, the key excited-state proton-coupled electron transfer reactions are barrierless. These findings could serve as guidelines for the realization of high-performance metal-free two-dimensional photocatalysts.

Promising two dimensional XSe2/SnS (X= Pt, Zr, Hf) vdW heterostructures for overall water splitting with higher carrier mobilities

The transition metal dichalcogenides (TMDs) are considered as promising candidates for their striking performance in optoelectronic properties. We have designed the novel heterostructures XSe2/SnS using XSe2 (X = Pt, Zr, Hf) TMDs. The stabilities of structural, mechanical, dynamical, and thermal are calculated by formation energies, elastic constants, phonon dispersions and AIMD simulations respectively. The hybrid functional (HSE06) is used to calculate the electronic band structures and optical absorption. The DFT scheme (BGC based) indicates that XSe2/SnS vdWHs are viable photocatalyst for overall water splitting over a broad spectrum of light. The absorption spectra exhibit that these photocatalysts have absorption started from visible to the UV region of light in the order of 105. XSe2/SnS heterostructures display high carrier mobilities of order 104. The Gibbs free energies exhibit that PtSe2/SnS heterostructure has spontaneous, whereas other heterostructures need some external energies for overall water splitting. Finally, the corrected STH efficiency of PtSe2/SnS, ZrSe2/SnS and HfSe2/SnS vdW heterostructures are 12.54%, 28.15%, 21.03% respectively. This study depicts that XSe2/SnS (X = Pt, Zr, Hf) heterostructures are feasible candidates for overall water splitting over a broad range of light spectrum.

First-principles study of the electronic, optical adsorption, and photocatalytic water-splitting properties of a strain-tuned SiC/WS2 heterojunction

Heterojunction is widely acknowledged as a potent strategy as an effective means for achieving quality electronic, optical adsorption, and photocatalytic water-splitting properties. Strain also can regulate these properties effectively. In this study, we have fabricated and studied a heterojunction comprised SiC and WS2. Utilizing a first-principles method, we systematically investigated the SiC/WS2 heterojunction's structure, stability, electronic, and optical properties, as well as its photocatalytic water splitting characteristics under strain engineering. Our calculations reveal that the SiC/WS2 heterojunction is a type-II heterostructure with two stable structures, which exhibits a direct bandgap and well performance in the visible light region, facilitating efficient separation of photogenerated electron-hole pairs. We have explored and discussed the impacts of biaxial strain on the various properties. The bandgaps of System-A and B are 1.778 eV and 1.820 eV, respectively, without strain. Under strain from −6% to 10%, they initially rise, peak at 1.858 eV and 1.899 eV respectively at −2% strain, then decline. Without strain, effective mass mh/me for both structures are 1.642 and 1.673. Under positive strain, they increase, decrease, then increase again, peaking at 6% with 2.116 and 2.260. At −2% strain, values drop to 0.901 and 0.910 for A and B, respectively. Our calculations also demonstrate that the SiC/WS2 heterostructure qualifies as a promising photocatalytic material, fulfilling the criteria for water splitting under strain conditions of −4%, −2%, and 0%. And the heterojunction with System-B under −4% strain has the optimal performance in photocatalytic water splitting. At a strain of −4%, System-B achieves the maximum η′STH of 16.91%. In conclusion, our study not only offers fundamental insights into the utilization of SiC/WS2 heterojunctions for photocatalytic water splitting, but also provides the foundational design principles of heterojunctions.

Preparation and characterization of ZnS/metal/ZnS transparent conductive multilayer films with different metal layers

ZnS/metal/ZnS transparent conductive multilayer films were deposited on quartz glass by pulsed laser deposition at room temperature with Au, Ag and Cu as the metal layers, and annealed in air at 100, 200 and 300℃ for 1 h. XRD patterns show that β -ZnS(111) diffraction peak of ZnS/Au/ZnS is stronger and sharper than the other two samples, indicating that its crystalline quality is the best. SEM images show the good structural homogeneity of the samples with smooth and compact film surfaces. When the annealing temperature increases from 100 to 300℃, the sheet resistance decreases first and then increases, while the carrier concentration changes in the opposite trend. The maximum transmittance (~85%) for ZnS/Au/ZnS in the visible light region is observed when the sample is annealed at 200℃. The figure of merit is calculated, and the best sample suitable for transparent conductive electrode is determined.

Synthesis, structural characterization and intense far-red luminescence of Mn4+ -activated SrLaMgTa1-yAlyO6 oxide phosphors

The transition metal Mn4+ activated phosphors have attracted increasing attention due to the potential uses in phosphor-converted lighting emitting diodes (LEDs). Herein, the far-red emitting SrLaMgTa1-yAlyO6:Mn4+ (y = 0−0.15) oxide phosphors were successfully synthesized by the high-temperature solid state reaction, in which the Mn4+ acted as an activator. The monoclinic double perovskite crystal structure, chemical composition, and 4+ state of activator Mn were confirmed by means of X-ray diffraction Rietveld refinement, scanning electron microscopy elemental mapping, and X-ray photoelectron spectroscopy. The optical properties were characterized with photoluminescence excitation and emission spectra, temperature-dependent emission spectra, and electroluminescence spectra. The excitation spectra are interweaved with the ligand-to-metal charge transfer band of Mn−O and intrinsic transitions (4A2g→4T1g, 4A2g→2T2g, and 4A2g→4T2g) of Mn4+, locating at the ultraviolet and blue light region. The emission spectra mainly contain a dominant far-red emission band from 650 to 775 nm with peaks at 695 and 708 nm, which are ascribed to the 2Eg→4A2g transition of Mn4+. Moreover, the cationic substitution strategy with tiny Al3+ occupying Ta5+ octahedral site, promotes the improvement of luminescence intensity and optical thermal stability. The quantum yield of optimal phosphor reaches 88.2 % and the fluorescence intensity at 373 K (100 °C) retains 83.4 % in respect to that at ambient temperature, implying the phosphor with intense and thermally stable luminescence. The phosphor is packaged with 365 nm chip to fabricate an LED device, and the electroluminescence result is quite consistent with the photoluminescence, matching well with the absorption spectrum of the phytochrome. The Mn4+ activated oxide phosphors with intense far-red emission are promising for plant cultivation lighting.

Self‐Powered Cs3Bi2I9/ZnO Heterojunction Photodetector with Dual‐Band Photoresponse

AbstractCs3Bi2I9/ZnO heterostructures are constructed by the growth of Cs3Bi2I9 layer onto the spin‐coated ZnO films by a modified antisolvent recrystallization method, a series of Cs3Bi2I9/ZnO heterojunction photodetectors (PDs) with varied growth times of Cs3Bi2I9 layer are fabricated. The construction of Cs3Bi2I9/ZnO heterojunction contributes to their improved photoelectric performance compared to ZnO‐based PD, and the Cs3Bi2I9 layer thickness plays an important role in tuning the photoelectric performance of these PDs. At 405 nm and 0 V bias, the optimized 6‐Cs3Bi2I9/ZnO PD generates a high photocurrent of −3.03 µA, a medium on/off ratio of 144.3, and a short response time of 16.4 ms/16.8 ms. It also exhibits superior dual‐band self‐powered photoresponse with two responsivity and detectivity peaks at 380 nm in the UV region and at 430 nm in the visible light region. At 380 nm, this PD presents the highest responsivity of 33.2 mA W−1 and detectivity of 1.07 × 1010 Jones. It is believed that the optimized growth of the Cs3Bi2I9 layer generates a depletion layer with suitable thickness near the interface, and the as‐promoted charge‐carrier separation and transport result in improved self‐powered properties. The rational construction of perovskite‐based heterojunction has proved as an efficient way to achieve self‐powered photodetection.

Optimizing junction interface integrity between 3D/2D defect pyrochlore Bi1.8Fe0.2WO6 and g-C3N4 nanostructures: A novel multifunctional nanocomposite for enhanced photocatalytic and photo-electrocatalytic water splitting and water remediation applications

In this work, a simplistic composite fabrication of defect pyrochlore Bi1.8Fe0.2WO6 (BFWO) and g-C3N4 (g-CN) was carried out to augment the photocatalytic degradation kinetics and Hydrogen (H2) evolution rate. The structural confirmation through XRD and FTIR confirmed the successful formation of pristine g-C3N4, BFWO NPs, and their composites. FESEM micrographs revealed multilayered sheet-like formation for C3N4 whereas irregular cuboid-shaped structure for BFWO NPs. In the composite formation, the sheets tended to appear wrapped around the BFWO NPs. The UV-DRS absorbance spectra exhibited a highlighted increase in the absorbance region towards the visible light region following a decrease in the band gap. The photoluminescence lifetime studies revealed an enhanced lifetime of excitons to 6.21 ns for 50:50 (g-C3N4: BFWO) composite formation, whereas pristine g-CN displayed an average lifetime of about 4.79 ns. The degradation efficacy in the removal of RhB and MB from water revealed up to 100% and 95.5% removal rates in under 90 mins and 180 mins respectively using the 50:50 composite formation. Similarly, the H2 evolution rate was significantly improved and exhibited up to 370 μmol/h/g. The photo-electrochemical studies revealed a sharp charge separation of excitons for 50:50 (g-C3N4: BFWO) with a maximum photocurrent density of -0.54 μA/cm2 @ 0 V which is 3.6 times and 13.5 times higher than bare g-CN and BFWO. 1.33 V vs. RHE for OER kinetics and -0.09 V vs RHE for HER kinetics were the minimal onset potential exhibited for equal ratios of BFWO and g-CN. Coupled with the heightened charge separation, reduced recombination rate, and optimal band edge positions, the photocatalytic efficiency in the degradation of RhB and MB and water-splitting reactions were improved.

Investigation of structural, optical characteristics of Gd3+ doped phosphate glass for radiation shielding applications

Gadolinium doped phosphate glass was created with a composition of 70 P2O5 + 5Al2O3 + 5 Ba2CO3 + 9 KF2 + 5 MnO2 + 5 SnO+1 Gd2O3 by using the melt-quenching process. The prepared glass sample’s amorphous nature was confirmed by the X-ray diffraction analysis. FT-IR examination confirms the presence of phosphate functional groups. Glass’s optical band gap was found to be 3.5 eV using Tauc’s plot method. The photoluminescence analysis indicates that the emission band at around 311 nm. The Commission International de I’Eclairage (CIE) was employed. It was identified that the computed chromaticity coordinate values (x = 0.3164 and y = 0.3371) were situated in the summer sunlight zone, close to the white light region. The attenuation capabilities of the gadolinium-doped phosphate glass sample were validated by the gamma ray shielding parameters. The mass attenuation coefficient and Mean free path of the prepared glass were fund to be 4.41 × 105 cm2/g at 0.015 MeV and 12.4 cm at 15 MeV respectively. In terms of infiltration deepness up to 40 MFP, the energy-related energy buildup factor (EBF) and energy absorption buildup factor (EABF) of glasses were calculated using the five (a, b, c, d, and Xk) parameters of the G-P fitting scheme. All of the results show that the synthetic glass can be used as shielding materials against gamma radiation.

Synergistic Approach of TiO2@MnZnO3 Heterostructure for Efficient Photoelectrochemical Water Splitting

The superior kinetics of charge carriers and greater visible light absorption are important factors for enhancing photoelectrochemical performance. Herein, the core–shell heterostructure has been developed by encapsulating single-phase MnZnO3 over TiO2 nanotubes by aerosol-assisted chemical vapor deposition approach. The fabricated photoanodes have been characterized by employing various techniques including X-ray diffraction, Raman spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, atomic force microscopy, and photoluminescence. Moreover, the mechanism for electron/hole transfer has been focused by a brief electrochemical investigation. The bilayer 1D/2D TiO2@MnZnO3 photoanode exhibited higher current density (2 mA cm−2) as compared to pristine TiO2-nanotubes (0.174 mA cm−2) at 1.52 V vs RHE. The superior photoactivity of heterostructure is attributed to the rapid transfer of photogenerated charge carriers via the Type-II mechanism. Furthermore, the reduced band gap (2.05 eV) accounts for good absorption in the visible region of light, while the interfacial electric field allowed the improved charge separation. The synergistic strategy in the present work demonstrates the promising significance of a heterojunction interface to optimize photovoltaic devices.

Research on optical properties of Eu3+ doped bismuth silicate crystals based on first principles

This paper is based on the first principles of density functional theory and uses the virtual crystal approximation method to calculate and analyze the optical properties of differently proportioned Eu3+-doped Bismuth silicate (Bi4Si3O12, or BSO). The results show that minor Eu3+ doping (1/12–1/3) improves the polarization ability of BSO and reduces energy loss. Additionally, doping an appropriate amount of Eu3+ (1/12–1/3) can improve light absorption and transmission of BSO to some extent. That is to say, Eu3+ doping improves the response of BSO to infrared light, and the absorption capacity in the ultraviolet and visible light regions is also enhanced. The theoretical research in this paper elucidates the changes in the optical properties of BSO after doping with Eu3+, providing a theoretical basis for expanding its application as a scintillation crystal in high-energy physics experiments, nuclear medicine, and other fields.