A direct Z-scheme g-C3N4/SnS2 photocatalyst with superior visible-light CO2 reduction performance

Highlights - SnS2 quantum dots anchored in situ on g-C3N4 by a simple one-step hydrothermal method. - The internal electric field between g-C3N4 and SnS2 was confirmed. - Internal-electric-field-induced direct Z-scheme g-C3N4/SnS2 charge transfer for enhanced photocatalytic CO2 reduction. - In situ FTIR analysis further proved the suggested photocatalytic mechanism. Abstract Photocatalytic reduction of CO2 to solar fuels is an ideal approach to simultaneously solve the global warming and energy crisis issues. Constructing a direct Z-scheme heterojunction is an effective way to overcome the drawbacks of single-component or conventional heterogeneous photocatalysts for photocatalytic CO2 reduction. Here, a novel type of direct Z-scheme g-C3N4/SnS2 heterojunction was constructed by depositing SnS2 quantum dots onto the g-C3N4 surface in situ via a simple one-step hydrothermal method. l-Cysteine not only acted as the sulfur source, but also grafted ammine groups onto g-C3N4 in the hydrothermal process, which greatly enhanced the CO2 uptake of the composite. XPS analysis and density functional theory (DFT) calculation show that electron transfer occurred from g-C3N4 to SnS2, resulting in the formation of interfacial internal electric fields (IEF) between the two semiconductors at equilibrium. As a result, Z-scheme charge transfer took place under photoexcitation, with the electrons in SnS2 combining with the holes in g-C3N4, which improved the extraction and utilization of photoinduced electron in g-C3N4. The g-C3N4/SnS2 hybrid shows superior photocatalytic CO2 reduction as compared with individual g-C3N4 and SnS2, which should be attributed to the IEF-induced direct Z-scheme as well as improved CO2 adsorption capacity. In situ FTIR spectra illustrate that HCOOH appeared as an intermediate during the CO2 conversion, which can only be generated by g-C3N4 according to the energy level of the photoinduced electrons, further confirming the Z-scheme configuration for the g-C3N4/SnS2 system

Coupling mechanisms of static and dynamic loads during the ultrasonic impact strengthening of Ti-6Al-4V

The ultrasonic impact-strengthening technology was used to effectively improve the fatigue resistance of the key components, which could be attributed to the association of static and dynamic impact loads. It is widely used in the high-performance manufacturing of critical aerospace components, such as titanium alloys. During the ultrasonic impact-strengthening process, the static and dynamic loading can provide two different deformation mechanisms, which may cause differences in the strengthening effect of the titanium alloys. This study developed an ultrasonic impact-strengthening test platform to investigate the influence mechanisms of static loads and cyclic dynamic impact loads in the ultrasonic impact-strengthening process. Meanwhile, the experiment platform was based on displacement control and could apply either static loads or cyclic dynamic impact loads individually on the surface of the Ti-6Al-4V. The force values in the static load experiments, cyclic dynamic impact experiments, and ultrasonic impact strengthening experiments were analyzed. The results show that the force value in the ultrasonic impact strengthening process is not only the superposition of the static load and the cyclic dynamic impact load, but indicating a coupling effect. The force of ultrasonic impact strengthening process increased by more than 55% compared to the sum of the static load and the maximum dynamic impact load. Moreover, the deformation strain rate of Ti-6Al-4V under separate cyclic dynamic impact loading was simulated. During the ultrasonic impact strengthening process, the deformation strain rate of Ti-6Al-4V could reach 960 s−1, 1587 s−1, and 2043 s−1 when the cyclic impact depths of 5 μm, 10 μm, and 15 μm, respectively. At the same time, the material surface hardening mechanism under the high strain rate cyclic impact loading was analyzed. The hardness of Ti-6Al-4V after the ultrasonic impact-strengthening process increased by more than 11% compared to the original hardness. At last, the strengthening performance of Ti-6Al-4V after the ultrasonic impact strengthening was evaluated. The strengthening mechanisms of static and dynamic loads during the ultrasonic impact strengthening of Ti-6Al-4V was investigated

MMP-2 and 9 in Chronic Kidney Disease

Gelatinases are members of the matrix metalloproteinase (MMPs) family; they play an important role in the degradation of the extracellular matrix (ECM). This effect is also crucial in the development and progression of chronic kidney disease (CKD). Its expression, as well as its activity regulation are closely related to the cell signaling pathways, hypoxia and cell membrane structural change. Gelatinases also can affect the development and progression of CKD through the various interactions with tumor necrosis factors (TNFs), monocyte chemoattractant proteins (MCPs), growth factors (GFs), oxidative stress (OS), and so on. Currently, their non-proteolytic function is a hot topic of research, which may also be associated with the progression of CKD. Therefore, with the in-depth understanding about the function of gelatinases, we can have a more specific and accurate understanding of their role in the human body

Catalyst-Free Thiol-Yne Click Polymerization: A Powerful and Facile Tool for Preparation of Functional Poly(vinylene sulfide)s

The "thio-click" polymerization is a well-expanded concept of click polymerization. Among the click polymerizations, the thiol-yne click polymerization is less developed and still in its infancy stage. In general, UV light, elevated temperature, amine, or transition metal complexes is needed to catalyze the thiol-yne click polymerization, which greatly complicates the experimental operation and limits its application. In this work, a facile and powerful thiol-yne click polymerization was developed, which could be carried out under very mild conditions without using external catalyst. Simply mixing the aromatic diynes (1a-1e) and dithiols (2-4) with equivalent molar ratio in THF at 30 degrees C will readily produce soluble and regioregular functional poly(vinylene sulfide)s (PIa-PIe, PII, and PIII) with high molecular weights (M-w, up to 85 200) in excellent yields (up to 97%) after as short as 2 h. Furthermore, no double addition product of an ethynyl group was found. This catalyst-free thiol-yne click polymerization has remarkably simplified the reaction conditions and will facilitate the preparation of functional materials applied in diverse areas

A Polytriazole Synthesized by 1,3-Dipolar Polycycloaddition Showing Aggregation-Enhanced Emission and Utility in Explosive Detection

The metal-free click polymerizations (MFCPs) of activated alkynes and azides have become a powerful technique for the preparation of functional polytriazoles. Recently, a new MFCP of activated azide and alkyne has been established, but no functional polytriazole is prepared. In this paper, polytriazole PIa with aggregation-enhanced emission (AEE) characteristics is prepared by this efficient polymerization in excellent yield (97.9%). PIa is thermally stable, with 5% loss of its weight at temperature as high as 440 degrees C. Thanks to its unique AEE feature of PIa, its nanoaggregates can be used to detect explosives with a superamplification quenching effect

Multi-Functional Hyperbranched Poly(vinylene sulfide)s Constructed via Spontaneous Thiol–Yne Click Polymerization

Multifunctional hyperbranched polymers have found wide applications in diverse areas. However, the preparation of these polymers is generally under harsh polymerization conditions with limited reactions. In this work, we prepared multifunctional hyperbranched poly­(vinylene sulfide)­s (<i>hb</i>-PVSs) by our established efficient and spontaneous thiol–yne click polymerization for the first time. A series of <i>hb</i>-PVSs with high molecular weights (<i>M</i>_w up to 63100) were obtained in high yields (up to 86%) from the polymerizations of monomers <b>1</b> and <b>2</b> with equivalent molar ratio in THF at 20 °C for 2 h. All the <i>hb</i>-PVSs are regioregular, soluble, and thermally stable. Thanks to the unreacted ethynyl groups on their peripheries, the <i>hb</i>-PVSs could be facilely functionalized by consecutive thiol–yne click reactions. Moreover, the solid films of <i>hb</i>-PVSs exhibit higher refractive index (RI) values (<i>n</i> > 1.64) than those of traditional optical plastics. The TPE-containing <i>hb</i>-PVS shows unique aggregation-enhanced emission characteristic and its aggregates could be used to detect explosives with superamplification effect. Therefore, this work not only proves the universality of our developed spontaneous thiol–yne click polymerization but also provides a powerful and versatile platform for the preparation of multifunctional sulfur-containing polymers

Catalyst-Free Thiol–Yne Click Polymerization: A Powerful and Facile Tool for Preparation of Functional Poly(vinylene sulfide)s

The “thio-click” polymerization is a well-expanded concept of click polymerization. Among the click polymerizations, the thiol–yne click polymerization is less developed and still in its infancy stage. In general, UV light, elevated temperature, amine, or transition metal complexes is needed to catalyze the thiol–yne click polymerization, which greatly complicates the experimental operation and limits its application. In this work, a facile and powerful thiol–yne click polymerization was developed, which could be carried out under very mild conditions without using external catalyst. Simply mixing the aromatic diynes (<b>1a</b>–<b>1e</b>) and dithiols (<b>2</b>–<b>4</b>) with equivalent molar ratio in THF at 30 °C will readily produce soluble and regioregular functional poly­(vinylene sulfide)­s (P<b>Ia</b>–P<b>Ie</b>, P<b>II</b>, and P<b>III</b>) with high molecular weights (<i>M</i>_w up to 85 200) in excellent yields (up to 97%) after as short as 2 h. Furthermore, no double addition product of an ethynyl group was found. This catalyst-free thiol–yne click polymerization has remarkably simplified the reaction conditions and will facilitate the preparation of functional materials applied in diverse areas