Density functional calculations of efficient H_2 separation from impurity gases(H_2,N_2,H_2O,CO,Cl_2, and CH_4)via bilayer g-C_3N_4 membrane

Membrane technology has been used for H_2 purification. In this paper, the systematic density functional simulations are conducted to study the separation of H_2 from the impurity gases(H_2, N_2, H_2 O, CO, Cl_2, and CH_4) by the bilayer porous graphitic carbon nitride(g-C_3 N_4) membrane. Theoretically, the bilayer g-C3 N4 membrane with a diameter of about3.25 A? should be a perfect candidate for H_2 purification from these mixed gases, which is verified by the high selectivity(S) for H_2 over other kinds of gases(3.43 × 1028 for H_2/N2; 1.40 × 1028 for H_262/H_2 O; 1.60 × 10 for H_2/CO; 4.30 × 10^(14) for H_2/Cl_2; 2.50 × 10^(55) for H_2/CH_4), and the permeance(P) of H_2(13 mol/m^2·s·Pa) across the bilayer g-C_3 N_4 membrane at 300 K, which should be of great potential in energy and environmental research. Our studies highlight a new approach towards the final goal of high P and high S molecular-sieving membranes used in simple structural engineering.

环氧合酶2及相关microRNA在心力衰竭患者血浆中表达水平研究

目的探讨环氧合酶2(COX-2)及相关微小RNA(microRNA)在心力衰竭患者血浆中的表达水平,为心力衰竭患者诊断和治疗提供更多帮助。方法选取我院2018年3月-2019年5月期间收治的60例冠心病合并心力衰竭患者,将其作为本次调查研究的主要观察对象,纳入观察组。同时选取60例冠心病未合并心力衰竭患者,将其作为对照组,对比两组患者COX-2、microRNA水平。结果观察组COX-2水平高于对照组,观察组microRNA下调趋势明显高于对照组,对比差异有统计学意义(P<0.05);观察组与对照组超声心动图检查相关指标左心室射血分数(LVEF)、左室后壁厚度(LVPW)、左室舒张末期内径(LVEDD)水平存在明显差异,对比有统计学意义(P<0.05);观察组和对照组三酰甘油(TG)、高密度脂蛋白(HDL-C)、低密度脂蛋白(LDL-C)、肌酐(Cr)水平对比无明显差异(P>0.05)。结论合并心力衰竭的冠心病患者,其COX-2、microRNA在血浆中呈高表达状态,对评估患者病情具有较大帮助。

Efficient Photolytic Halogenation and Oxidation of Unactivated Alkyl sp^(3) C—H Bonds with Iodine(III)

A metal-free,green,and sustainable functionalization of unactivated alkyl sp^(3) C—H bonds is reported using iodine(III)as a feasible dehydrogenation agent under visible light or KBr,and alkyl chlorides,bromides,alcohols,and ketones could be constructed by addition of different coupling reagents.Cheap and safe iodobenzene diacetate was used to form a radical to activate the alkyl sp^(3) C—H bond in a highly efficient manner,which can construct different alkylation products by adding corresponding coupling reagents.

Advanced 2D molybdenum disulfide for green hydrogen production: Recent progress and future perspectives

The development of renewable and affordable energy is crucial for building a sustainable society. In this context, establishing a sustainable infrastructure for renewable energy requires the integration of energy storage, specifically use of renewable hydrogen. The hydrogen evolution reaction (HER) of electrochemical water splitting is a promising method for producing green hydrogen. Recently, two-dimensional nanomaterials have shown great promise in promoting the HER in terms of both fundamental research and practical applications due to their high specific surface areas and tunable electronic properties. Among them, molybdenum disulfide (MoS2), a non-noble metal catalyst, has emerged as a promising alternative to replace expensive platinum-based catalysts for the HER because MoS_(2)has a high inherent activity, low cost, and abundant reserves. At present, greatly improved activity and stability are urgently needed for MoS_(2)to enable wide deployment of water electrolysis devices. In this regard, efficient strategies for precisely modifying MoS_(2)are of interest. Herein, the progress made with MoS_(2)as an HER catalyst is reviewed, with a focus on modification strategies, including phase engineering, morphology design, defect engineering, heteroatom doping, and heterostructure construction. It is believed that these strategies will be helpful in designing and developing high-performance and low-cost MoS2-based catalysts by lowering the charge transfer barrier, increasing the active site density, and optimizing the surface hydrophilicity. In addition, the challenges of MoS_(2)electrocatalysts and perspectives for future research and development of these catalysts are discussed.

Remarkable-cycle-performanceβ-bismuthene/graphene heterostructure anode for Li-ion battery

Remarkable Li-ion battery(LIB)anode materials need to have long cycle life and fast charge/discharge rate,however they are difficult to be realized in the monolayer anode materials.The monolayerβ-Bi has the stiffness of only 33.0 N/m,thus the Bi/G heterostructure is proposed to improve the electronic and mechanical properties and to produce better LIB anode performance in this paper.The calculated results show that Bi/G heterostructure has excellent thermodynamic,dynamical and mechanical stability.The band gap is only 0.04 eV,which ensures remarkable electrical conductivity.In addition,the Bi/G heterostructure has higher stiffness(369.2 N/m)than that of monolayerβ-Bi and graphene.The diffusion barrier(E_(barrier)) of 0.32 e V and volume expansion ratio(VER)of only 4%can ensure the rapid transport of Li^(+) ions in the charge/discharge cycling process and long life of the LIB.These calculated theoretical results for describing the detail properties of Li storage and diffusion in the Bi/G heterostructure can supply adequate conclusive evidence for the prediction of remarkable properties of Bi/G heterostructure as an anode material for LIBs.

Preparation and thermoelectric properties of Cu1.8S/CuSbS2 composites

Chalcostibite(CuSbS2)is composed of earth-abundant elements and has a proper band gap(Eg=1.05 eV)as a thermoelectric(TE)material.Herein,we report the TE properties in the CuSbS2 based composites with a mole ratio of(1–x)CuSbS2–x Cu1.8S(x=0,0.1,0.2,0.3),which were prepared by mechanical alloying(MA)combined with spark plasma sintering(SPS).X-ray diffraction(XRD)and back-scattered electron image(BSE)results indicate that a single phase of CuSbS2 is synthesized at x=0 and the samples consist of CuSbS2,Cu3SbS4,and Cu12Sb4S13 at 0.1≤x≤0.3.The correlation between the phase structure,microstructure,and TE transport properties of the bulk samples is established.The electrical conductivity increases from 0.14 to 50.66 S·cm–1 at 723 K and at0≤x≤0.03,while the Seebeck coefficient holds an appropriate value of 190.51μV·K–1.The highest ZT value of 0.17 is obtained at 723 K and at x=0.3 owing to the combination of a high PF183μW·m–1·K–2 and a lowκ0.8 W·m–1·K–1.

Single-phase La_(0.8)Sr_(0.2)Co_(1-x)Mn_(x)O_(3-δ) electrocatalyst as a triple H^(+)/O^(2-)/e^(-) conductor enabling high-performance intermediate-temperature water electrolysis

Hydrogen,especially the“green hydrogen”based on water electrolysis,is of great importance to build a sustainable society due to its high-energy-density,zero-carbon-emission features,and wide-range applications.Today's water electrolysis is usually carried out in either low-temperature(<100℃),e.g.,alkaline electrolyzer,or high-temperature(>700℃)applications,e.g.,solid oxide electrolyzer.However,the low-temperature devices usually suffer from high applied voltages(usually>1.5 V@0.01 A cm^(-2))and high cost;meanwhile,the high-temperature ones have an unsatisfied lifetime partially due to the incompatibility among components.Reasonably,an intermediate-temperature device,namely,proton ceramic cell(PCC),has been recently proposed.The widely-used air electrode for PCC is based on double O^(2-)/e^(-)conductor or composited O^(2-)/e^(-)-H^(+)conductor,limiting the accessible reaction region.Herein,we designed a single-phase La_(0.8)Sr_(0.2)Co_(1-x)Mn_(x)O_(3-δ)(LSCM)with triple H^(+)/O^(2-)/e^(-)conductivity as the air electrode for PCCs.Specifically,the La_(0.8)Sr_(0.2)Co_(0.8)Mn_(0.2)O_(3-δ)(LSCM8282)incorporates 5.8%proton carriers in molar fraction at 400℃,indicating superior proton conducting ability.Impressively,a high current density of 1580 mA cm^(-2) for hydrogen production(water electrolysis)is achieved at 1.3 V and 650℃,surpassing most low-and high-temperature devices reported so far.Meanwhile,such a PCC can also be operated under a reversible fuel cell mode,with a peak power density of 521 mW cm^(-2) at 650℃.By correlating the electrochemical performances with the hydrated proton concentration of single-phase triple conducting air electrodes in this work and our previous work,a principle for rational design of high-performance PCCs is proposed.

Synthesis of nickel selenide thin films for high performance all-solid-state asymmetric supercapacitors

As a significant semiconductor,nickel selenide shows enormous potential and extensive application pro spects in the field of sensor,photocatalysis and supercapacito r.In this paper,nickel selenide(Ni3Se2,NiSe) thin films were successfully fabricated on stainless-steel sheet using a facile,effective electrodeposition technique.The morphologies,microstructures and chemical compositions of the thin films are characterized systematically.Electrochemical tests exhibit that the Ni3Se2 and NiSe possess high specific capacitance of 581.1 F/g and 1644.7 F/g,respectively.A flexible,all-solid-state asymmetric supercapacitor is assembled by utilizing NiSe film as positive electrode and activated carbon as negative electrode.The solid device delivers a high areal capacitance of 27.0 mF/cm2 at the current density of 0.7 mA/cm2.The maximum volumetric energy density and powerdensity of the NiSe//AC asymmetric SCs can achieve 0.26 mWh/cm3 and 33.35 mW/cm3,respectively.The device shows robust cycling stability with 84.6% capacitance retention after 10,000 cycles,outstanding flexibility and satis factory mechanical stability.Moreover,two devices in series can light up a red light-emitting diode,which displayed great potential applications for energy storage.

Green hydrogen production by intermediate-temperature protonic solid oxide electrolysis cells:Advances,challenges,and perspectives

Protonic solid oxide electrolysis cells(P-SOECs)operating at intermediate temperatures,which have low costs,low environmental impact,and high theoretical electrolysis efficiency,are considered promising next-generation energy conversion devices for green hydrogen production.However,the developments and applications of P-SOECs are restricted by numerous material-and interface-related issues,including carrier mismatch between the anode and electrolyte,current leakage in the electrolyte,poor interfacial contact,and chemical stability.Over the past few decades,considerable attempts have been made to address these issues by improving the properties of P-SOECs.This review comprehensively explores the recent advances in the mechanisms governing steam electrolysis in P-SOECs,optimization strategies,specially designed components,electrochemical performance,and durability.In particular,given that the lack of suitable anode materials has significantly impeded P-SOEC development,the relationships between the transferred carriers and the cell performance,reaction models,and surface decoration approaches are meticulously probed.Finally,the challenges hindering P-SOEC development are discussed and recommendations for future research directions,including theoretical calculations and simulations,structural modification approaches,and large-scale single-cell fabrication,are proposed to stimulate research on P-SOECs and thereby realize efficient electricity-to-hydrogen conversion.