Efficient water splitting over a hybrid photocatalyst with (002) active facets and heterostructure.

A series of P-CdS@P-MWOx (M = Ni, Mn, Co, Zn, Fe, Cu) hybrid photocatalysts was constructed using different transition metal polyoxometalates [SiW11M(H2O)O39]n- as precursors via a pyrolysis-phosphidation strategy. Under visible light irradiation (λ = 420 nm), P-CdS@P-NiWOx shows a good H2 evolution rate of 418.4 µmol g-1 h-1 and an AQE of 29.9% at 420 nm without adding a sacrificial reagent, which is a nearly 140-fold enhancement over CdS. This study provides a feasible strategy for designing efficient photocatalysts with highly active facets and heterostructure.

CBCT study on the safe location of palatal microscrew implant anchorage nail between maxillary first and second molars / 口腔疾病防治

Objective@#Conebeam CT (CBCT) was used to measure the palatine between the maxillary first and second molars. The proximal and distal palatal widths of the maxillary first and second molar and the palatal mucosal thickness and bone tissue thickness when microscrew implant anchorage nail were implanted at different angles provided a reference for the clinical selection of microscrew implant placement.@* Methods@#The image data of 90 adult patients were selected as the research object, and the jaw bone was reconstructed by scanning. In maxillary palatine, selection of distances at 12 mm, 14 mm, 16 mm, and 18 mm from the palatal apex of maxillary first molar between the maxillary first and second molar were used as measurement, measured the proximal and distal palatal widths of maxillary first and second molar and the palatal mucosal thickness and bone tissue thickness when microscrew implant anchorage nails were implanted at 30 °, 45 °, 60 °, and 90 °. SPSS 26.0 software was used for one-way ANOVA and LSD pair comparison. @*Results@#The larger the angle of the microscrew implant anchorage nail was, the smaller the proximal and distal medial widths between the maxillary first and second molar, and the difference was statistically significant (P < 0.05). Compared with the 90° direction, the proximal and distal medial widths of the microscrew implant anchorage nail were larger in the 60° direction. The greater the angle of implantation, the smaller the mucosal thickness and the greater the bone tissue thickness, and the results showed a significant difference (P < 0.001). Compared with the direction of 30° and 45°, the mucosal thickness at the direction of 60° was smaller, and the bone tissue thickness was larger. The higher the position of the microscrew implant anchorage nail, the greater the width of the proximal and distal medial, and the difference was statistically significant (P < 0.05). Compared with the positions 12 and 14 mm from the palatal tip, the proximal and distal medial widths of the microscrew implant anchorage nail were larger. The higher the implant position was, the greater the mucosal thickness and the smaller the bone tissue thickness. The results showed a significant difference (P < 0.001). Compared with the position of 18 mm from the palatal tip of the maxillary first molar, the mucosal thickness was smaller and the bone tissue thickness was larger.@*Conclusion@#It is most appropriate to implant microscrew implant anchorage nail at least 10 mm in length in the direction of 60° at the palatal apex 16 mm from the maxillary first molar in palatine between the first and second molar.

Morphology Engineering of BiVO4 with CoOx Derived from Cobalt-containing Polyoxometalate as Co-catalyst for Oxygen Evolution.

Bismuth vanadate (BiVO4 ) as a metal oxidation semiconductor has stimulated extensive attention in the photocatalytic water splitting field. However, the poor transport ability and easy recombination of charge carriers limit photocatalytic water oxidation activity of pure BiVO4 . Herein, the photocatalytic activity of BiVO4 is enhanced via adjusting its morphology and combination co-catalyst. First, the Cu-BiVO4 was synthesized by copper doping to control the growth of {110} facet of BiVO4 , which is regarded for the separation of photo-generated charge carriers. Then the CoOx in-situ generated from K6 [SiCoII (H2 O)W11 O39 ] ⋅ 16H2 O was photo-deposited on Cu-BiVO4 surface as co-catalyst to speed up reaction kinetics. Cu-BiVO4 @CoOx hybrid catalyst shows highest photocatalytic activity and best stability among all the prepared catalysts. Oxygen evolution is about 34.6 µmol in pH 4 acetic acid buffer under 420 nm LED irradiation, which is nearly 20 times higher than that of pure BiVO4 . Apparent quantum efficiency (AQE) in 1 h and O2 yield are 1.83% and 23.1%, respectively. O2 evolution amount nearly maintains the original value even after 5 cycles.

A homogeneous Cu-based polyoxometalate coupled with mesoporous TiO2 for efficient photocatalytic H2 production.

Developing a photocatalytic system for water splitting to H2 is a promising strategy to address fossil fuel consumption. Exploring photocatalysts with high-performance, steady and low-cost has been the essential goals toward photo-reduction of water. Herein, noble-metal-free polyoxometalate Na12[(α-SbW9O33)2Cu3(H2O)3]·46H2O (Cu3POM) was coupled with mesoporous, multiphase TiO2 (Meso-TiO2) for the first time to catalyze hydrogen production. The composite system exhibited excellent photocatalytic hydrogen production activity. After 2.5 h of illumination, the activity was enhanced 77 times (1284.8 µmol/g) in the presence of Cu3POM compared to the blank Meso-TiO2 (16.6 µmol/g). Nitrogen adsorption-desorption isotherms results reveal the mesoporous characteristics of Meso-TiO2 which could increase the active sites of the reaction. The cycling experiment demonstrated the composite system remained stable after five cycles without activity loss. Multiple characterizations reveal that Ti3+ is generated after the reaction, which further narrows the band gap and promotes the photocatalytic performance of the composite system. The suitable LUMO energy level of Cu3POM was confirmed by electrochemical tests. It accelerates the transfer of photo-generated electrons from the CB of Meso-TiO2 to the protons in the solution, resulting in a high photocatalytic H2 production performance. The combination of Meso-TiO2 with reductive polyoxometalate innovatively provides novel insights into the design of efficient photocatalytic materials for H2 production.

Immobilization of Metal-Organic Framework MIL-100(Fe) on the Surface of BiVO4: A New Platform for Enhanced Visible-Light-Driven Water Oxidation.

The development of new dual functional photocatalysts is highly desirable for conversion and storage of solar energy. Herein, we first constructed hierarchical structure MIL-100(Fe)@BiVO4 in situ growing MIL-100(Fe) nanoparticles (NPs) on the surface of decahedron BiVO4 under mild hydrothermal conditions. The as-synthesized hybrid nanostructure is unambiguously determined using a series of characterization methods. These results demonstrate that the ultra-tiny MOF MIL-100(Fe) particles are immobilized on the surface of decahedron BiVO4 and the composite exhibits a strong interaction between BiVO4 and MIL-100(Fe). This hybrid material MIL-100(Fe)@BiVO4 is employed as a photocatalyst for water oxidation reaction and demonstrates higher O2 production activity in comparison with bare BiVO4. The best performance obtained at the optimal mass percentage of MIL-100(Fe) (8.0 wt %) reaches 333.3 µmol h-1 g-1 of the O2 evolution rate irradiated with visible light, which is almost 4.3 times higher than bare BiVO4 (77.3 µmol h-1 g-1). The enhanced water oxidation performance is due to the more efficient interfacial electron-hole transfer between MIL-100(Fe) and BiVO4, which is verified by the results of various photo-electrochemical characterizations. Moreover, the as-prepared composite MIL-100(Fe)@BiVO4 also displays excellent stability for visible-light-driven water oxidation. This study affords a rational strategy for the controllable construction by loading metal-organic frameworks on a semiconductor surface, which is a good reference for other artificial photosystems.

A stable iron-containing polyoxometalate coupled with semiconductor for efficient photocatalytic water oxidation under acidic condition.

A robust water oxidation system using BiVO4 as light-harvesting material and iron-containing polyoxometalate Fe11 as cocatalyst is constructed, in which an apparent quantum efficiency of 25.3% and a turnover frequency (TOFinitial) of 173 h-1 are obtained. Most importantly, the iron-containing polyoxometalate remains stable and intact during the reaction process through the pH adjustment strategy and plays a true molecular cocatalyst role in the semiconductor photocatalytic water oxidation system.

Enhanced Photoelectrochemical Performance of WO3 -Based Composite Photoanode Coupled with Carbon Quantum Dots and NiFe Layered Double Hydroxide.

An attractive photoanode material, WO3 , has suffered from its limited visible-light absorption and sluggish surface reaction kinetics, as well as poor stability in neutral electrolytes. Herein, a NiFe/CQD/WO3 composite photoanode was designed and fabricated, with loading of carbon quantum dots (CQDs) and electrodeposition of NiFe layered double hydroxide. The NiFe/CQD/WO3 photoanode obtained a photocurrent density of 1.43 mA cm-2 at 1.23 V vs. reversible hydrogen electrode, which is approximately three times higher than that of bare WO3 . During the test period of 3 h, the stability of WO3 was improved substantially after the loading of cocatalysts. Furthermore, mechanistic insights of the favored band structure and beneficial charge-transfer pathway elucidate the high photoelectrochemical performance of the NiFe/CQD/WO3 composite photoanode.