Ag3PO4 Microcrystals Synthesized by Room-Temperature Solid State Reaction:Enhanced Photocatalytic Activity and Photoelectronchemistry Performance

Ag3PO4 microcrystals with highly enhanced visible light photocatalytic activity are prepared by a facile and simple solid state reaction at room temperature. The composition, morphology and optical properties of the asprepared Ag3PO4 microcrystMs are characterized by x-ray diffraction, scanning electron microscopy and UV-vis diffuse reflectance spectra. The photocatalytie properties of Ag3PO4 are investigated by the degradation of both methylene blue and methyl orange dyes under visible light irradiation. The as-prepared Ag3PO4 microcrystals possess high photocatalytic oxygen production with the rate of 673μmolh-1g-1. Moreover, the as-prepared Ag3PO4 microcrystals show an enhanced photoelectrochemistry performance under irradiation of visible light.

Understanding Sulfur Redox Mechanisms in Different Electrolytes for Room-Temperature Na-S Batteries

This work reports influence of two different electrolytes,carbonate ester and ether electrolytes,on the sulfur redox reactions in room-temperature Na-S batteries.Two sulfur cathodes with different S loading ratio and status are investigated.A sulfur-rich composite with most sulfur dispersed on the surface of a carbon host can realize a high loading ratio(72%S).In contrast,a confined sulfur sample can encapsulate S into the pores of the carbon host with a low loading ratio(44%S).In carbonate ester electrolyte,only the sulfur trapped in porous structures is active via‘solid-solid’behavior during cycling.The S cathode with high surface sulfur shows poor reversible capacity because of the severe side reactions between the surface polysulfides and the carbonate ester solvents.To improve the capacity of the sulfur-rich cathode,ether electrolyte with NaNO_(3) additive is explored to realize a‘solid-liquid’sulfur redox process and confine the shuttle effect of the dissolved polysulfides.As a result,the sulfur-rich cathode achieved high reversible capacity(483 mAh g^(−1)),corresponding to a specific energy of 362 Wh kg^(−1) after 200 cycles,shedding light on the use of ether electrolyte for high-loading sulfur cathode.

Room-temperature conversion of ethane and the mechanism understanding over single iron atoms confined in graphene

The catalytic conversion of ethane to high value-added chemicals is significantly important for utilization of hydrocarbon resources.However, it is a great challenge due to the typically required high temperature(> 400 ℃) conditions.Herein, a highly active catalytic conversion process of ethane at room temperature(25 ℃) is reported on single iron atoms confined in graphene via the porphyrin-like N4-coordination structures.Combining with the operando time of flight mass spectrometer and density functional theory calculations, the reaction is identified as a radical mechanism, in which the C–H bonds of the same C atom are preferentially and sequentially activated, generating the value-added C2 chemicals, simultaneously avoiding the over-oxidation of the products to CO2.The in-situ formed O–FeN4–O structure at the single iron atom serves as the active center for the reaction and facilitates the formation of ethyl radicals.This work deepens the understanding of alkane C–H activation on the FeN4 center and provides the reference in development of efficient catalyst for selective oxidation of light alkane.

Synthesis and Characterization of Rare Earth Ion Doped Nano ZnO

Zinc oxide(ZnO) doped with erbium at different concentrations was synthesized by solid-state reaction method and characterized by X-ray diffraction(XRD), scanning electron microscopic(SEM), UVabsorption spectroscopy, photoluminescence(PL) study and vibrating sample magnetometer. The XRD studies exhibit the presence of wurtzite crystal structure similar to the parent compound ZnO in 1% Er^(3+)doped Zn O,suggesting that doped Er^(3+)ions sit at the regular Zn^(2+)sites. However, same studies spread over the samples with Er^(3+)content>1% reveals the occurrence of secondary phase. SEM images of 1% Er^(3+)doped ZnO show the polycrystalline nature of the synthesized sample. UV-visible absorption spectrum of Er^(3+)doped ZnO nanocrystals shows a strong absorption peak at 388 nm due to ZnO band to band transition. The PL study exhibits emission in the visible region, due to excitonic as well as defect related transitions. The magnetizationfield curve of Er^(3+)doped ZnO nanocrystals showed ferromagnetic property at room-temperature.

Tailorable Multi-Photoresponsive Behavior Triggered by Different Sulfur Oxidation States

Photoresponsive materials are considered as promising systems for intelligent technology applications owing to the contactless spatial and temporal control.Herein,controllable multi-photoresponsive behaviors are realized in benzo[b]thiophene derivatives(o-DMP-S,o-DMP-SO,and o-DMP-SO_(2))by modulating the sulfur oxidation state.Among them,o-DMP-S is photo-unreactive but possesses denser molecular packing upon ultraviolet(UV)light irradiation,exhibiting photoenhanced room-temperature phosphorescence properties.Through stoichiometric oxidation of the sulfur atom in o-DMP-S,the resulting sulfoxide compound o-DMP-SO undergoes a radical photolysis reaction involving photodeoxygenation and photochemical rearrangement,thereby leading to the photomechanical effect.The sulfone compound o-DMP-SO_(2)displays prominent reversible photochromism,resulting from the radical photocyclization under 365 nm UV light irradiation.Based on comprehensive experimental and computational investigations,the diverse photoresponsive behaviors of these benzo[b]thiophene derivatives are demonstrated to depend on the intersystem crossing efficiency and radical-mediated photochemical reaction activity in excited states due to the different sulfur oxidation states.This work provides an insightful understanding of the relationship between molecular structure and photoresponsive behavior and opens up the opportunity for the development of photoresponsive materials with potential applications.

Solid-Liquid State Bonding of Si3N4 Ceramics with Ceramic-Modified Brazing Alloy

Solid-liquid state bonding of Si3N4 ceramics with TiN-modified Ag-Cu-Ti brazing alloy was used'- to enhance joint strength. The effects of the TiN particles on the microstructures, interfacial reactions, and room-temperature properties of the joints were investigated. The results show that the TiN particles are gen- erally well dispersed in the Ag-Cu eutectic base and the interface between them is both clean and com-pact. Changes in the TiN volume fractions from 0 to 20% exert no noticeable effect on the interfacial reac-tion between Ag-Cu-Ti and the substrates. Other bonding parameters being constant, the TiN volume frac-tion in the filler material plays a key role in the joint properties. For TiN volume fractions below 20%, the joints are reinforced, especially joints with 5% and 20% TiN. The average shearing strength of joints with 5% TiN is 200.8 MPa, 30% higher than that of joints with no TiN (154.1 MPa). However, for TiN volumes frac- tions above 20%, the joint strengths decrease.