PdCu alloy anchored defective titania for photocatalytic conversion of carbon dioxide into methane with 100% selectivity

The photoreduction of CO_(2)into CH_(4)with simultaneous high activity and selectivity is a promising strategy to increase energy supply and alleviate global warming.However,the absence of the active sites that is responsible for the adsorption and activation of CO_(2)and the generation of CO and H2via side reactions often lead to poor efficiency and low selectivity of the catalyst.Herein,Cu,Pd,and PdCu metal clusters cocatalyst-anchored defective TiO_(2)nanotubes(Cu/TiO_(2)-SBO,Pd/TiO_(2)-SBO,and Pd1Cu1/TiO_(2)-SBO)were designed via a simple solution impregnation reduction and applied for photocatalytic conversion of CO_(2)to CH_(4).The Pd1Cu1/TiO_(2)-SBO photocatalyst exhibits excellent catalytic performance among the other catalysts for photoreduction of CO_(2)into CH_(4).More interestingly,the product selectivity of CH_(4)reaches up to 100%with a rate of 25μmol g^(-1)h^(-1).In-situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)and density functional theory(DFT)simulations indicate that the main reasons for the high selectivity of CH_(4)are attributed to the PdCu alloy and oxygen vacancies,which jointly enhance the photoinduced carrier separation and lower energy barriers of key intermediates.Moreover,due to the tunable d-band center of the Cu site in the PdCu alloy,the generated intermediates can be well prevented from poisoning and promoted to participate in further reactions.Hopefully,the current study will provide insight into the development of new,highly selective photocatalysts for the visible light-catalytic reduction of CO_(2)into CH_(4).

Unveiling the redox electrochemistry of 1D,urchin-like vanadium sulfide electrodes for high-performance hybrid supercapacitors

Exploring novel versatile electrode materials with outstanding electrochemical performance is the key to the development of advanced energy conversion and storage devices.In this work,we aim to construct new-fangled one-dimensional(1D)quasi-layered patronite vanadium tetrasulfide(VS_(4))nanostructures by using different sulfur sources,namely thiourea,thioacetamide,and L-cysteine through an ethyleneaminetetraacetic-acid(EDTA)-mediated solvothermal process.The as-prepared VS4exhibits several unique morphologies such as urchin,fluffy nanoflower,and polyhedron with appropriate surface areas.Among the prepared nanostructures,the VS_(4)-1@NF nanostructure exhibited excellent electrochemical properties in 6 M KOH solution,and we explored its redox electrochemistry in detail.The asprepared VS_(4)-1@NF electrode exhibited battery-type redox characteristics with the highest capacity of280 C g^(-1)in a three-electrode assembly.Moreover,it offered a capacity of 123 F g^(-1)in a hybrid twoelectrode set-up at 1 A g^(-1)with the highest specific energy and specific power of 38.5 W h kg^(-1)and750 W kg^(-1),respectively.Furthermore,to ensure the practical applicability and real-world performance of the prepared hybrid AC@NF//VS_(4)-1@NF cell,we performed a cycling stability test with more than 5,000galvanostatic charge–discharge cycles at 2 A g^(-1),and the cell retained around 84.7%of its capacitance even after 5,000 cycles with a CE of 96.1%.

组成可调的ZnS1-xSex纳米带固溶体的构筑与高效太阳燃料制备

在光能作用下,利用半导体催化剂将CO2和H2O转化为太阳燃料(H2和CO),有望同时减少碳排放和获取高附加值的替代能源与化工产品,因而成为研究热点之一.半导体光催化剂具有较宽的光谱响应范围和合适的导价带位置(即光生电子/空穴应具有适宜的还原/氧化能力),这是其作为高效催化剂的前提条件之一.但是,当调控半导体的禁带宽带以使其有利于捕获太阳能时,通常也会同时改变其导价带位置,从而影响光生电子/空穴的还原/氧化能力,降低反应驱动力,进而可能导致光催化活性降低.根据能带工程理论,构筑固溶体是一种有效地改变该窘境的方法.它主要是通过调控固溶体组成,进而调控其能带结构,即不仅能够调控半导体材料的光谱响应范围(调控禁带宽带),还能调控半导体的导价带位置(调控光生电子/空穴的还原/氧化能力),从而实现反应光捕获与驱动力之间的最佳平衡,达到提高半导体催化剂光催化性能的目的.ZnS具有较好的光催化性能,但其禁带宽度较高,不利于对可见光的吸收.考虑到ZnS和ZnSe都具有六方纤锌矿结构,且S和Se的电负性和二价负离子半径相近,因此,本文以ZnS1–xSex(en)0.5为前驱体,通过简便易行的热处理法,成功制备了具有不同组成的ZnS1–xSex纳米带固溶体.结果发现,通过改变反应物中的Se/S摩尔比可调控所得固溶体的组成,进而调控其能级排列(禁带宽度与导价带位置等),第一性原理计算进一步证实了该实验结果.当Se/S的摩尔比从0增加到1时,所得固溶体的禁带宽度在3.69~2.68 eV之间连续可调;同时,导带底不断向下移动,而价带顶持续向上移动,即光生电子/空穴的还原/氧化能力不断降低.利用所得样品进行光催化还原制备太阳燃料实验,发现ZnS0.75Se0.25表现出最高的光催化活性.这主要是因为在该固溶体中实现了光捕获(禁带宽带)与反应驱动力(光生电子/空穴的还原/氧化能力)的最佳平衡.因此,本文有助于更好地设计与制备基于固溶体的高效光催化剂,从而为将来的实际应用奠定理论与实验基础.

红壤有机矿物复合体吸附Cu(Ⅱ)的分子机制

采用元素分析、X射线衍射分析(XRD)、同步辐射扫描透射显微术(STXM)等手段,表征湖南祁阳红壤中颗粒态有机质(Particle organic matter,POM)和有机矿物复合体(Organo-mineral complexes,OMC)的元素组成、矿物组成,以及Cu(Ⅱ)在土体土壤(Bulksoil,BS)和OMC表面的吸附行为、元素微区分布和分子固定机制,以明确实际土壤系统有机矿物复合体对铜吸附的能力及其固定机制。元素分析、XRD结果表明,土体土壤主要由OMC组成,富含黏土矿物,且所含有机质矿化度较BS和POM组分高。等温吸附实验结果表明,BS和OMC等温吸附曲线符合Langmuir和Freundlich方程,BS及OMC对Cu(Ⅱ)吸附等温线类似,且理论最大吸附量相当,说明供试土壤对Cu(Ⅱ)的吸附主要由OMC决定。STXM在亚微米尺度上表征了BS和OMC吸附样品中Cu与C、Fe、Al、Si的微区分布特征,发现Cu在红壤中分布具有空间异质性,Cu主要与羧基碳与铁氧化物形成的有机矿物复合体相结合,控制着红壤中Cu(Ⅱ)的形态分布与有效性。

Numerical Solution for Accelerated Rotating Disk in a Viscous Fluid

The problem of a disk rotating in a viscous fluid has been investigated. The disk is accelerated with angular velocity proportional to time. Employing suitable similarity transformations the governing partial differential equations are transformed in to ordinary differential form. The resulting equations are solved numerically using SOR method and Simpson’s (1/3) rule. The results have been improved by using Richardson’s extrapolation. The effect of the non-dimensional parameter s which measures unsteadiness is observed on velocity components, skin friction coefficient and torque of the disk.

Novel MAC Layer Proposal for URLLC in IndustrialWireless Sensor Networks

Ultra-reliable and low-latency communications(URLLC) has become a fundamental focus of future industrial wireless sensor net-works(IWSNs). With the evolution of automation and process control in industrial environments, the need for increased reliabilityand reduced latencies in wireless communications is even pronounced. Furthermore, the 5G systems specifically target the URLLCin selected areas and industrial automation might turn into a suitable venue for future IWSNs, running 5G as a high speed inter-process linking technology. In this paper, a hybrid multi-channel scheme for performance and throughput enhancement of IWSNsis proposed. The scheme utilizes the multiple frequency channels to increase the overall throughput of the system along with theincrease in reliability. A special purpose frequency channel is defined, which facilitates the failed communications by retransmis-sions where the retransmission slots are allocated according to the priority level of failed communications of different nodes. Ascheduler is used to formulate priority based scheduling for retransmission in TDMA based communication slots of this channel.Furthermore, in carrier-sense multiple access with collision avoidance(CSMA/CA) based slots, a frequency polling is introducedto limit the collisions. Mathematical modelling for performance metrics is also presented. The performance of the proposed schemeis compared with that of IEEE802.15.4e, where the performance is evaluated on the basis of throughput, reliability and the num-ber of nodes accommodated in a cluster. The proposed scheme offers a notable increase in the reliability and throughput over theexisting IEEE802.15.4e Low Latency Deterministic Networks(LLDN) standard.

特定位点上CO2与（TiO2）n团簇相互作用的第一性原理研究（英文）

本文基于密度泛函理论系统地研究了(TiO2)n团簇上二氧化碳(CO2)的吸附和活化性质.计算结果表明,CO2更倾向于吸附在(TiO2)n团簇的桥氧原子上,形成"化学吸附"碳酸盐络合物.而CO更倾向于吸附到末端Ti-O的Ti原子上.发现计算得到的碳酸盐振动频率值与实验获得的结果非常吻合,这表明配合物中CO2的几何构型与其线性型相比,有微小的弯转.通过对电子结构、电荷密度、电离势、HOMO-LUMO以及态密度的分析,证实了CO2与团簇之间的电荷转移以及相互作用.从预测的能量分布图来看,(TiO2)n团簇上的CO2活化与结构密切有关,相比于块体的TiO2,CO2在团簇结构上更易于吸附和活化.

Cooperative Subcarrier Sensing Using Antenna Diversity Based Weighted Virtual Sub Clustering

The idea of cooperation and the clustering amongst cognitive radios(CRs) has recently been focus of attention of research community, owing to its potential to improve performance of spectrum sensing(SS) schemes. This focus has led to the paradigm of cluster based cooperative spectrum sensing(CBCSS). In perspective of high date rate 4th generation wireless systems, which are characterized by orthogonal frequency division multiplexing(OFDM) and spatial diversity, there is a need to devise effective SS strategies. A novel CBCSS scheme is proposed for OFDM subcarrier detection in order to enable the non-contiguous OFDM(NC-OFDM) at the physical layer of CRs for efficient utilization of spectrum holes. Proposed scheme is based on the energy detection in MIMO CR network, using equal gain combiner as diversity combining technique, hard combining(AND, OR and Majority) rule as data fusion technique and antenna diversity based weighted clustering as virtual sub clustering algorithm. Results of proposed CBCSS are compared with conventional CBCSS scheme for AND, OR and Majority data fusion rules. Moreover the effects of antenna diversity, cooperation and cooperating clusters are also discussed.

New Ninth Order J-Halley Method for Solving Nonlinear Equations

In the paper [1], authors have suggested and analyzed a predictor-corrector Halley method for solving nonlinear equations. In this paper, we modified this method by using the finite difference scheme, which had a quantic convergence. We have compared this modified Halley method with some other iterative methods of ninth order, which shows that this new proposed method is a robust one. Some examples are given to illustrate the efficiency and the performance of this new method.

Melting Characteristics of a Phase Change Material Mixed with Nano Particles of Cobalt Oxide Bounded in a Trapezoidal Structure

A novel trapezoidal design for storage of heat energy through melting of phase-change material(PCM)is investigated.Latent heat thermal energy storage system(LHTES)is a promising option to diminish mis-match between energy consumption and supply.For this purpose,Paraffin:Rubitherm-35(RT35)material is successively melted in aluminum structure which is heated from one side and the other sides are kept adiabatic.Melting of PCM is observed experimentally and melt fronts are photographed for various time lengths.The fluid-solid module in COMSOL Multiphysics 5.4 has been utilized.The transient heat conduction with enthalpy function is hired.Simulations are carried out for enhancement of thermal conductivity through addition of nano-entities of cobalt oxide Co3O4.Themelting time is notably reduced with inclusion of nano-entities to enhance thermal conductivity.The time spans for melt start and total melt in case of pure PCM are 375 and 4500(s)respectively whereas for the nano mix case,these are 150 and 3000 s.Thus 33%shorter time length is noticed for charging of the PCM trapezoidal matrix with nano entities of Co3O4 aremixed.The results fromsimulation and lab observations depict similar patterns and are in quite close comparison.

Numerical Solution for a Similar Flow between Two Disks in the Presence of a Magnetic Field

Numerical solutions are obtained for non-steady, incompressible fluid flow between two parallel disks which at time t are separated by a distance H(1-αt)1/2 and a magnetic field proportional to B0(1-αt) -1/2 is applied perpendicular to the disks where H denotes a representative length, BO denotes a representative magnetic field and α-1 denotes a representative time. Similarity transformations are used to convert the governing partial differential equations of motion in to ordinary differential form. The resulting ordinary differential equations are solved numerically using SOR method, Richardson extrapolation and Simpson’s (1/3) Rule. Our numerical scheme is straightforward, efficient and easy to program.

The Rotationally Symmetric Flow of Micropolar Fluids in the Presence of an Infinite Rotating Disk

The rotationally symmetric flow of a micropolar fluid in the presence of an infinite rotating disk has been studied numerically. The equations of motion are reduced to a system of ordinary differential equations, which in turn are solved numerically using SOR method and Simpson’s (1/3) rule. The results are calculated for different values of the parameter s (the ratio of angular velocities of disc and fluid) and the suction parameter a. Moreover, three different sets of the values of non-dimensional material constants related to micropolar behavior of the fluid have been chosen arbitrarily. The calculations have been carried out using three different grid sizes to check the accuracy of the results. The research concludes that the micropolar fluids flow resembles with that of Newtonian fluids when the material constants become close to zero. The comparison of these results is presented for possible values of the parameter s.

The Accelerated Rotating Disk in a Micropolar Fluid Flow

The problem of a micropolar fluid about an accelerated disk rotating with angular velocity Ω proportional to time has been studied. By means of the usual similarity transformations, the governing equations are reduced to ordinary non-linear differential equations and then solved numerically, using SOR method and Simpson’s (1/3) rule for s ≥ 0, where s is non-dimensional parameter which measures unsteadiness. The calculations have been carried out using three different grid sizes to check the accuracy of the results. The results have been improved by using Richardson’s extrapolation.

Comparative Efficacy of Different Inactivated Hydro-Pericardium Syndrome Vaccines Prepared from Infected Liver and Vero Cell Line Adapted Adeno Type 4 Virus

Hydro-Pericardium Syndrome (HPS) is viral problem of commercial poultry caused by aviadeno virus type-4. In Pakistan the problems have been controlled by administering inactivated infected liver homogenate vaccine (ILHV). The use of liver based HPS vaccines remained potential threat for having hypersensitivity reactions in poultry. The current study was carried out to compare the serological potency of HPS ILHV to vero cell line adopted vaccine in term of anti HPS-ELISA antibody titers. 14 HPS virus vaccines were prepared based on different concentration of antigen, type of adjuvants and source of virus substrate. Total of 160 birds were divided into 16 groups each containing 10 birds. At day of 14th age each bird of every group was injected with 0.3 ml dose of respective vaccine. It was observed that HPS infected liver based vaccine having 1 × 105.6, 1 × 105.6 and 1 × 103.6 bird lethal dose 50 induced 1092.10, 875.25 and 702.2 anti-HPS ELISA antibody titer respectively. The 20, 25 and 30 doses/gm HPS infected liver vaccine induced 110.4, 1071.9 and 1037.8 anti-HPS ELISA antibody titer respectively. Montanide based tissue culture HPS vaccine showed significantly higher 1148.45 anti-HPS ELISA antibody titer to aluminium hydroxide based vaccine (137.2) (P 5.6 TCID50 is serological potent against field infection. The vaccines based on such formulation could be prepared in future for effective immuno-prophylaxis against HPS virus.

Molecular Detection and Sequencing for S1 Glycoprotein Gene of Bronchitis Virus of 2016 Epidemic from Sindh and Punjab

Infectious Bronchitis (IB) is highly contagious disease of commercial poultry causing substantial economic loses by producing poor quality meat in broilers and effecting production in breeder birds. The causative agent has been reported as most hazardous pathogen among other infectious agent even after being immunized with multi-variant strain vaccine. Currently, different strain such as H-120, 4/91 and D274 have been used extensively for immunoprophylaxis against velogenic strain across Pakistan with minimal protection reported. In current study PCR analysis was used to investigate the molecular nature of IB isolates from Punjab and Sind province of Pakistan in 2016 epidemics. Total of 100 tracheal samples were considered for virus inoculation in 10 days old chicken embryonated eggs. The IBV infected amniotic fluid was neutralized with monoclonal antisera of H-120, 4/91 and D274 strains. The IBV screened samples were subjected for RNA extraction and subsequent to PCR using type specific primer of each strain. The amplified product of 840 bp was sequenced through Sanger sequencing. On the basis of PCR results, four similar amplified products from both regions were obtained showing similarities in agarose gel electrophoresis, but they differ from each other on the basis of nucleotides sequence. Phylogenetic analysis revealed that nucleotide sequences of isolates from Karachi were similar to the IBV H-120, Mass-41 and Connecticut 46 reference strains. Whereas, isolates from the Punjab province are analogous to the Mans-2, Mans-3, 9/41(UK) but did not show significant similarity with other reference strain. Therefore, it is recommended that use of M-41 and H-120 in vaccine production could be effective measure against velogenic infectious agent in Sindh particularly in Karachi, whereas, it would be better to incorporate either of the variant GQ281656.1, AY279533.1 in vaccine because of their highest level of resemblance with genetically sequenced isolates from Lahore and its surroundings.

CO oxidation on MXene(Mo_(2)CS_(2)) supported single-atom catalyst: A termolecular Eley-Rideal mechanism

Finding transition metal catalysts for effective catalytic conversion of CO to CO_(2)has attracted much attention.MXene as a new 2D layered material of early transition metal carbides,nitrides,and carbo-nitrides is a robust support for achoring metal atoms.In this study,the electronic structure,geometries,thermodynamic stability,and catalytic activity of MXene (Mo_(2)CS_(2)) supported single noble metal atoms (NM=Ru,Rh,Pd,Ir,Pt and Au) have been systematically examined using first-principles calculations and ab initio molecular dynamic (AIMD) simulations.First,AIMD simulations and phonon spectra demonstrate the dynamic and thermal stabilities of Mo_(2)CS_(2)monolayer.Three likely reaction pathways,LangmuirHinshelwood (LH),Eley-Rideal (ER),and Termolecular Eley–Rideal (TER) for CO oxidation on the Ru1-and Ir_(1)@Mo_(2)CS_(2)SACs,have been studied in detail.It is found that CO oxidation mainly proceeds via the TER mechanism under mild reaction conditions.The corresponding rate-determining steps are the dissociation of the intermediate (OCO-Ru_(1)-OCO) and formation of OCO-Ir_(1)-OCO intermediate.The downshift d-band center of Ru1-and Ir_(1)@Mo_(2)CS_(2)help to enhance activity and improve catalytst stability.Moreover,a microkinetic study predicts a maximum CO oxidation rate of 4.01×10^(2)s^(-1)and 4.15×10^(3)s^(-1)(298.15K) following the TER pathway for the Ru_(1)-and Ir_(1)@Mo_(2)CS_(2)catalysts,respectively.This work provides guideline for fabricating and designing highly efficient SACs with superb catalyts using MXene materials.

Exploring the experimental study and density functional theory calculations of symmetric and asymmetric chalcogen atoms interacted molybdenum dichalcogenides for lithium-ion batteries

Two-dimensional asymmetric chalcogen atoms attached to Janus nanoparticles have fascinated research attention owing to their distinctive properties and characteristics for various applications.This paper proposed a facile synthesis to produce efficient molybdenum-based symmetric and asymmetric chalcogens bounded by X Mo X and TeMo X nanostructures.Subsequently,the fabricated X Mo X and TeMo X nanostruc-tures were employed as anodes for lithiumion batteries(LIBs).Assembled LIBs using TeMoS and TeMoSe Janus anodes achieved 2610 and 2073 mAh g^(-1)reversible capacity at 0.1 A g^(-1),respectively for the halfcell configuration,which is outstanding performance compared with previous reports.Superior rate capability performances at 0.1-20 A g^(-1)and exceptional cycling solidity confirmed high charge and discharge capacities for TeMo X Janus lithium-ion battery anodes.In addition,the full cell device with TeMoS//LiCoO_(2)configuration explored the discharge capacity of 1605 mAh g^(-1)at 0.1 A g^(-1)which suggests their excellent electrochemical characteristics.The density functional theory approximations established the significance of assembled symmetric and asymmetric chalcogen atoms interacted with X Mo X and TeMo X anode materials for LIBs.Thus,the present investigation supports a new approach to creating two-dimensional materials based on asymmetric chalcogen atoms with core metal to effectively increase desirable energy storage characteristics.

非贵金属单原子催化剂Co_(1)/MXene(Mo_(2)CS_(2))的CO氧化反应机理研究

MXene是一类由前过渡态金属碳化物、氮化物或碳氮化物构成的新型二维材料.我们利用量子化学方法研究了单原子Co在新型二维MXene材料Mo2CS2上的吸附构型、稳定性和催化性质.研究发现Co原子可以稳定锚定在MXene材料的表面,形成的单原子催化剂适合于催化低温CO氧化.计算表明,吸附的CO和O2分子与Co_(1)/Mo_(2)CS_(2)催化剂表面之间的电荷转移在活化这些小分子时起着重要作用.我们研究了Co1/Mo2CS2催化氧化CO的三种机理:Eley-Rideal(ER),Langmuir-Hinshelwood(LH)和Termolecular Eley-Rideal(TER),发现在低温下这三种反应机理都是可行的.其中在Co_(1)/Mo_(2)CS_(2)催化剂上TER机理具有最高的催化活性,计算的决速步能垒分别为0.67(TER),0.78(LH)和0.88 eV(ER).我们的研究结果表明,利用二维材料MXene发展和设计经济的、非贵金属单原子催化剂具有重要应用前景.

A Review of Rechargeable Zinc-Air Batteries:Recent Progress and Future Perspectives

Zinc-air batteries(ZABs)are gaining attention as an ideal option for various applications requiring high-capacity batteries,such as portable electronics,electric vehicles,and renewable energy storage.ZABs offer advantages such as low environmental impact,enhanced safety compared to Li-ion batteries,and cost-effectiveness due to the abundance of zinc.However,early research faced challenges due to parasitic reactions at the zinc anode and slow oxygen redox kinetics.Recent advancements in restructuring the anode,utilizing alternative electrolytes,and developing bifunctional oxygen catalysts have significantly improved ZABs.Scientists have achieved battery reversibility over thousands of cycles,introduced new electrolytes,and achieved energy efficiency records surpassing 70%.Despite these achievements,there are challenges related to lower power density,shorter lifespan,and air electrode corrosion leading to performance degradation.This review paper discusses different battery configurations,and reaction mechanisms for electrically and mechanically rechargeable ZABs,and proposes remedies to enhance overall battery performance.The paper also explores recent advancements,applications,and the future prospects of electrically/mechanically rechargeable ZABs.

Eh耦合的稻田土壤镉、砷释放机制

镉(Cd)、砷(As)是稻田土壤的主要重(类)金属污染物,稻田土壤Cd、As的释放与其氧化还原电位(Eh)密切相关,但Eh耦合的稻田土壤砷、镉释放机制仍不清楚.本实验利用高精度土壤微反应器模拟Eh梯度变化过程(-250、-50、170 mV),研究其耦合的土壤Cd、As及相关元素(Fe、Al、Ca、S、P、DOC)的释放特征,并结合同步辐射微区X射线荧光光谱技术(μ⁃XRF)探讨了不同Eh(-250、-50、170 mV)条件下稻田土壤As释放机制.结果表明:随着供试体系Eh从-250 mV升高至170 mV,土水混合液中DOC和pH值逐步下降,但Cd、As及相关Al、S、P、Fe元素浓度则同时升高.其中,Cd与S、Al增长均呈先缓后快特征,而As与P、Fe增长则呈先快后缓趋势,说明在Eh升高过程中Cd与S,以及As与Fe间密切相关.同步辐射μ⁃XRF分析发现,在低Eh条件下,土壤颗粒上As、Fe和S的高含量点信号重合,As⁃S及As⁃Fe的可决系数分别在Eh为-250 mV和170 mV条件下最高,说明在低Eh条件下As很可能主要受硫化铁控制,但在高Eh条件下则受铁氧化物影响.综上可知,低Eh条件下,As、Cd主要受到硫化铁的控制.随着Eh的升高,土壤Cd的活性逐渐升高,As的活性则受到铁氧化物控制.本研究结果可为理解土壤Cd、As共同释放机制及调控土壤Cd、As活性提供重要理论依据.