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The quick recombination of photogenerated carriers and the high surface reaction barrier are two important aspects influencing photocatalytic hydrogen generation. In this paper, a sulfur vacancy-modified two-dimensional (2D) fluorinated-TiO2 nanosheet/Mn0.2Cd0.8S (F-TiO2/MCS) S-scheme heterojunction was synthesized by a simple hydrothermal method to accelerate photogenerated electron transfer. The formation of an S-scheme heterojunction between MCS nanoflowers and 2D F-TiO2 enhances the efficacy of photocatalytic hydrogen generation by facilitating the separation of photogenerated electron–hole pairs. Meanwhile, the sulfur vacancies of F-TiO2/MCS change the local electronic structure of the heterojunction surface by capturing photogenerated electrons, resulting in a photocatalytic hydrogen evolution rate for F-TiO2/MCS of 3197 μmol g–1 h–1, which is 4.42 times greater than that of the pure MCS. Experimental measurements and density functional theory (DFT) calculations show that the mutual synergy between the S-scheme heterojunction and the sulfur vacancies not only provides abundant H2 adsorption active sites but also promotes interfacial charge separation and migration, which improves the photocatalytic performance of the F-TiO2/MCS composite. This work holds significance for the photocatalytic hydrogen production of sulfur vacancy-modified S-scheme heterojunctions. [ABSTRACT FROM AUTHOR]

Electrochemical N2 reduction reaction (NRR) provides an alternative approach to producing ammonia (NH3) under ambient conditions. However, the sluggish kinetic process and existence of the competitive reaction of hydrogen evolution reaction make the catalytic activity and selectivity of NRR catalysts still very low. To tackle this challenge, gold-modified molybdenum carbide (Mo2C) nanoparticles (NPs) supported on nitrogen-doped carbon nanotubes (Au/Mo2C/NCNTs) was synthesized using a strategy that combines laser irradiation and carbothermal reaction. For such a composite, pony-sized Mo2C nanocrystals play important roles in cleavage of the NN bond and the occurrence of N2 adsorption, while Au NPs promote charge transfer and intermediate protonation to enhance the selectivity of NRR. Using these advantages, the NH3 yield rate and Faradaic efficiency of Au/Mo2C/NCNTs reached 46.89 μg mgcat.–1 h–1 and 2.78% at −0.3 V versus reversible hydrogen electrode, which were 2.36 and 3.20 times those of Mo2C/NCNTs, respectively. Our effort provides a unique pathway for preparing Au/Mo2C/NCNTs composites and gives insight into the mechanism of the NRR performance enhanced by metal NP loading and heteroatom doping. [ABSTRACT FROM AUTHOR]

Re-based transition metal dichalcogenides have attracted extensive attention owing to their anisotropic structure and excellent properties in applications such as optoelectronic devices and electrocatalysis. The present study methodically investigated the evolution of specific Raman phonon mode behaviors and phase transitions in monolayer and bulk ReSe 2 under high pressure. Considering the distinctive anisotropic characteristics and the vibration vectors of Re and Se atoms exhibited by monolayer ReSe 2 , we perform phonon dispersion calculations and propose a methodology utilizing pressure-dependent polarized Raman measurements to explore the precise structural evolution of monolayer ReSe 2 under the stress fields. Varied behaviors of the E g -like and A g -like modes, along with their specific vector transformations, have been identified in the pressure range 0-14.59 GPa. The present study aims to offer original perspectives on the physical evolution of Re-based transition metal dichalcogenides, elucidating their fundamental anisotropic properties and exploring potential applicability in diverse devices.

Ferroelectric lead-free K x Na 1- x NbO 3 (KNN) perovskite, whose piezoelectric properties can be comparable to those of traditional Pb-based systems, has aroused wide concern in recent years. However, the specific influences of the stress field on KNN's structure and piezoelectric properties have not been well clarified and there are few descriptions about the temperature-pressure phase diagram. Here, we analyzed the phonon mode behavior and structural evolution of K 0.5 Na 0.5 NbO 3 -0.05LiNbO 3 (KNN-LN) and MnO 2 -doped single crystals with pressure- and temperature-dependent phase structure variations by theoretical calculation, polarized Raman scattering, and infrared reflectance spectra. The different phase structures can be predicted at high pressure using the CALYPSO method with its same-name code. The rhombohedral → orthorhombic → tetragonal → cubic phase transition process can be discovered in detail by Raman spectra under different temperatures and pressures. The phase coexistence on the thermal phase boundary was confirmed by basic anastomosis. Meanwhile, it was found that the substitution of Mn in the NbO 6 octahedron aggravates the deformation of high pressure on KNN-LN and the substitution of Mn at the B-site intensifies the structural evolution more severely than at the A-site. The present study aims at exploring octahedra tilt, phonon vibrations, and the internal structure on the general critical phase boundary in KNN-LN crystals. It provides effective help for the study of lead-free perovskite phase transformation and the improvement in piezoelectric properties under a high-pressure field.

Timely restoration of blood supply following ischemia is critical to rescue damaged tissue. However, clinical efficacy is hampered by the inflammatory response after ischemia. Whether inflammation fine tunes the angiogenesis and the function of blood vessels via the heterogeneity of neutrophils remain poorly understood. Herein, the objective of this work is to incorporate the growth factors secreted by neutrophils into a porous gelatin methacrylate (GelMA) hydrogel, which subsequently is used as a novel regenerative scaffold with defined architecture for ischemia. We demonstrate that anti-inflammatory neutrophils (N 2 -polarized neutrophils) play an important role in promoting the migration of human umbilical vein endothelial cells (HUVECs) and formation of capillary-like networks in vitro . More importantly, vascular anastomosis can be achieved by modulating the neutrophils to N 2 phenotype. In addition, N 2 -polarized composite hydrogel scaffolds can regulate inflammation, maintain the survival of exogenous cells, and promote angiogenesis in vivo . Notably, the composite hydrogel scaffolds promote neovascularization during exogenous introduction of endothelial cells by anastomosis. Taken together, this study highlights N 2 -polarized neutrophils composite hydrogels can achieve vascularization rapidly by regulating inflammation and promoting vascular anastomosis. This work lays the foundation for research into the treatment of ischemia and may inspire further research into novel treatment options.

It is of great importance to understand the thermal properties of MoSe 2 films for electronic and optoelectronic applications. In this work, large-area polycrystalline MoSe 2 films are prepared using a low-cost, controllable, large-scale, and repeatable chemical vapor deposition method, which facilitates direct device fabrication. Raman spectra and X-ray diffraction patterns indicate a hexagonal (2H) crystal structure of the MoSe 2 film. Ellipsometric spectra analysis indicates that the optical band gap of the MoSe 2 film is estimated to be ∼1.23 eV. From the analysis of the temperature-dependent and laser-power-dependent Raman spectra, the thermal conductivity of the suspended MoSe 2 films is found to be ∼28.48 W/(m·K) at room temperature. The results can provide useful guidance for an effective thermal management of large-area polycrystalline MoSe 2 -based electronic and optoelectronic devices., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

Unprecedented copper-catalyzed regiodivergent hydrosilylation reactions of substituted 1,3-dienes with hydrosilanes have been developed. The 1,2- and 1,4-hydrosilylations of 1-(hetero)aryl-substituted 1,3-dienes were highly selectively controlled via variation of the catalytic systems. Meanwhile, the 1,4-hydrosilylation reaction of 2-aryl-substituted 1,3-dienes with diphenylsilane was also successfully realized for the first time. These methods provide convenient and efficient approaches for the synthesis of structurally diverse allylsilanes.

Emerging evidence suggests that successful healing of bone substitutes depends on the osteogenesis-angiogenesis interplay. Bone morphogenetic protein-2 (BMP-2) and vascular endothelial growth factor (VEGF) have been identified as key regulators of osteogenesis and angiogenesis during bone regeneration. While the importance of growth factors is now widely accepted, the impact and mechanisms of different releasing sequences on bone repair have not been fully understood. Here, a composite vehicle (Gel/PMs), constructed with hydrogels and microspheres, was developed, which is capable of achieving two distinct releasing modes: BMP-2 first release followed by VEGF release (B/V) and VEGF first release followed by BMP-2 release (V/B). In our results, the B/V mode exhibited more extensive vascular network formation by up-regulating angiogenic genes during the bone remolding, thus facilitating rapid bone transformation which was confirmed by radiography. Further histological and immune-staining analysis revealed that fast release of BMP-2 made for rapidly initiating osteogenesis, while later VEGF release promoted persistent angiogenesis and mature bone formation. Moreover, interest arises from the introduction of 2- N ,6- O -sulfated chitosan (SCS), a sulfonated heparin-like polysaccharide. It has synergistic effects with both BMP-2 and VEGF, which can further accelerate bone healing by efficiently improving osteogenesis and angiogenesis. The results demonstrated that disparate releasing sequence of growth factors might influence regenerative efficiency. Such a strategy may provide insights toward designing bioactive materials and give promising application in tissue regeneration.