Ga₄B₂O₉: An Efficient Borate Photocatalyst for Overall Water Splitting without Cocatalyst

Borates are well-known candidates for optical materials, but their potentials in photocatalysis are rarely studied. Ga³⁺-containing oxides or sulfides are good candidates for photocatalysis applications because the unoccupied 4s orbitals of Ga usually contribute to the bottom of the conducting band. It is therefore anticipated that Ga₄B₂O₉ might be a promising photocatalyst because of its high Ga/B ratio and three-dimensional network. Various synthetic methods, including hydrothermal (HY), sol–gel (SG), and high-temperature solid-state reaction (HTSSR), were employed to prepare crystalline Ga₄B₂O₉. The so-obtained HY-Ga₄B₂O₉ are micrometer single crystals but do not show any UV-light activity unless modified by Pt loading. The problem is the fast recombination of photoexcitons. Interestingly, the samples obtained by SG and HTSSR methods both possess a fine micromorphology composed of well-crystalline nanometer strips. Therefore, the excited e^– and h⁺ can move to the surface easily. Both samples exhibit excellent intrinsic UV-light activities for pure water splitting without the assistance of any cocatalyst (47 and 118 μmol/h/g for H₂ evolution and 22 and 58 μmol/h/g for O₂ evolution, respectively), while there is no detectable activity for P25 (nanoparticles of TiO₂ with a specific surface area of 69 m²/g) under the same conditions

Systematic Study of Cr³⁺ Substitution into Octahedra-Based Microporous Aluminoborates

Single crystals of pure aluminoborate PKU-1 (Al₃B₆O₁₁(OH)₅·<i>n</i>H₂O) were obtained, and the structure was redetermined by X-ray diffraction. There are three independent Al atoms in the <i>R</i>3 structure model, and Al3 locates in a quite distorted octahedral environment, which was evidenced by ²⁷Al NMR results. This distortion of Al3O₆ octahedra release the strong static stress of the main framework and leads to a symmetry lowering from the previously reported <i>R</i>3̅ to the presently reported <i>R</i>3. We applied a pretreatment to prepare Al³⁺/Cr³⁺ aqueous solutions; as a consecquence, a very high Cr³⁺-to-Al³⁺ substitution content (∼50 atom %) in PKU-1 can be achieved, which is far more than enough for catalytic purposes. Additionally, the preference for Cr³⁺ substitution at the Al1 and Al2 sites was observed in the Rietveld refinements of the powder X-ray data of PKU-1:0.32Cr³⁺. We also systematically investigated the thermal behaviors of PKU-1:<i>x</i>Cr³⁺ (0 ≤ <i>x</i> ≤ 0.50) by thermogravimetric–differential scanning calorimetry, in situ high-temperature XRD in vacuum, and postannealing experiments in furnace. The main framework of Cr³⁺-substituted PKU-1 could be partially retained at 1100 °C in vacuum. When 0.04 ≤ <i>x</i> ≤ 0.20, PKU-1:<i>x</i>Cr³⁺ transferred to the PKU-5:<i>x</i>Cr³⁺ (Al₄B₆O₁₅:<i>x</i>Cr³⁺) structure at ∼750 °C by a 5 h annealing in air. Further elevating the temperature led to a decomposition into the mullite phase, Al₄B₂O₉:<i>x</i>Cr³⁺. For <i>x</i> > 0.20 in PKU-1:<i>x</i>Cr³⁺, the heat treatment led to a composite of Cr³⁺-substituted PKU-5 and Cr₂O₃, so the doping upper limit of Cr³⁺ in PKU-5 structure is around 20 atom %

Additional file 1 of Immunoregulatory and neutrophil-like monocyte subsets with distinct single-cell transcriptomic signatures emerge following brain injury

Additional file 1: Figure S1. Dil-Liposome localizes in white blood cells, and is distributed in Iba1 + cells of liver and spleen, but not the brain. (A-B) Representative confocal images for brain cortex showing Dil-LPM (red) inside blood vessels (CD31 + , white) and not in microglia (Iba-1 + , green) or brain parenchyma. (E–G) Dil-LPM is not detected in the brain of naïve mice at 1 h (F) or 24 h after injection (G). (H) Representative confocal images showing Dil-LPM (red) staining in Iba1 + (green) cells in kidney, (I) liver parenchyma (J) and spleen. n = 5/group, *P < 0.05; **P < 0.01; ****P < 0.0001. One-way ANOVA with Bonferroni post hoc

Dendritic, Transferable, Strictly Monolayer MoS₂ Flakes Synthesized on SrTiO₃ Single Crystals for Efficient Electrocatalytic Applications

Controllable synthesis of macroscopically uniform, high-quality monolayer MoS₂ is crucial for harnessing its great potential in optoelectronics, electrocatalysis, and energy storage. To date, triangular MoS₂ single crystals or their polycrystalline aggregates have been synthesized on insulating substrates of SiO₂/Si, mica, sapphire, <i>etc.</i>, <i>via</i> portable chemical vapor deposition methods. Herein, we report a controllable synthesis of dendritic, strictly monolayer MoS₂ flakes possessing tunable degrees of fractal shape on a specific insulator, SrTiO₃. Interestingly, the dendritic monolayer MoS₂, characterized by abundant edges, can be transferred intact onto Au foil electrodes and serve as ideal electrocatalysts for hydrogen evolution reaction, reflected by a rather low Tafel slope of ∼73 mV/decade among CVD-grown two-dimensional MoS₂ flakes. In addition, we reveal that centimeter-scale uniform, strictly monolayer MoS₂ films consisting of relatively compact domains can also be obtained, offering insights into promising applications such as flexible energy conversion/harvesting and optoelectronics

PKU-3: An HCl-Inclusive Aluminoborate for Strecker Reaction Solved by Combining RED and PXRD

A novel microporous aluminoborate, denoted as PKU-3, was prepared by the boric acid flux method. The structure of PKU-3 was determined by combining the rotation electron diffraction and synchrotron powder X-ray diffraction data with well resolved ordered Cl^– ions in the channel. Composition and crystal structure analysis showed that there are both proton and chlorine ions in the channels. Part of these protons and chlorine ions can be washed away by basic solutions to activate the open pores. The washed PKU-3 can be used as an efficient catalyst in the Strecker reaction with yields higher than 90%

Controlled Growth of High-Quality Monolayer WS₂ Layers on Sapphire and Imaging Its Grain Boundary

Atomically thin tungsten disulfide (WS₂), a structural analogue to MoS₂, has attracted great interest due to its indirect-to-direct band-gap tunability, giant spin splitting, and valley-related physics. However, the batch production of layered WS₂ is underdeveloped (as compared with that of MoS₂) for exploring these fundamental issues and developing its applications. Here, using a low-pressure chemical vapor deposition method, we demonstrate that high-crystalline mono- and few-layer WS₂ flakes and even complete layers can be synthesized on sapphire with the domain size exceeding 50 × 50 μm². Intriguingly, we show that, with adding minor H₂ carrier gas, the shape of monolayer WS₂ flakes can be tailored from jagged to straight edge triangles and still single crystalline. Meanwhile, some intersecting triangle shape flakes are concomitantly evolved from more than one nucleus to show a polycrystalline nature. It is interesting to see that, only through a mild sample oxidation process, the grain boundaries are easily recognizable by scanning electron microscopy due to its altered contrasts. Hereby, controlling the initial nucleation state is crucial for synthesizing large-scale single-crystalline flakes. We believe that this work would benefit the controlled growth of high-quality transition metal dichalcogenide, as well as in their future applications in nanoelectronics, optoelectronics, and solar energy conversions