Temperature-Dependent Anisotropy and Two-Band Superconductivity Revealed by Lower Critical Field in Organic Superconductorκ-(BEDT-TTF)_(2)Cu[N(CN)_(2)]Br

Resistivity and magnetization have been measured at different temperatures and magnetic fields in organic superconductorsκ-(BEDT-TTF)_(2)Cu[N(CN)_(2)]Br.The lower critical field and upper critical field are determined,which allow to depict a complete phase diagram.Through the comparison between the upper critical fields with magnetic field perpendicular and parallel to the conducting ac-planes,and the scaling of the in-plane resistivity with field along different directions,we find that the anisotropyΓis strongly dependent on temperature.It is realized thatΓis quite large(above 20)near Tc,which satisfies the 2D model,but approaches a small value in the low-temperature region.The 2D-Tinkham model can also be used to fit the data at high temperatures.This is explained as a crossover from the orbital depairing mechanism in high-temperature and low-field region to the paramagnetic depairing mechanism in the high-field and low-temperature region.The temperature dependence of lower critical field,Hc1(T),shows a concave shape in wide temperature region.It is found that neither a single d-wave nor a single s-wave gap can fit the Hc1(T),however a two-gap model containing an s-wave and a d-wave can fit the data rather well,suggesting two-band superconductivity and an unconventional pairing mechanism in this organic superconductor.

Overlapping community‐based particle swarm optimization algorithm for influence maximization in social networks

Influence maximization,whose aim is to maximise the expected number of influenced nodes by selecting a seed set of k influential nodes from a social network,has many applications such as goods advertising and rumour suppression.Among the existing influence maximization methods,the community‐based ones can achieve a good balance between effectiveness and efficiency.However,this kind of algorithm usually utilise the network community structures by viewing each node as a non‐overlapping node.In fact,many nodes in social networks are overlapping ones,which play more important role in influence spreading.To this end,an overlapping community‐based particle swarm opti-mization algorithm named OCPSO for influence maximization in social networks,which can make full use of overlapping nodes,non‐overlapping nodes,and their interactive information is proposed.Specifically,an overlapping community detection algorithm is used to obtain the information of overlapping community structures,based on which three novel evolutionary strategies,such as initialisation,mutation,and local search are designed in OCPSO for better finding influential nodes.Experimental results in terms of influence spread and running time on nine real‐world social networks demonstrate that the proposed OCPSO is competitive and promising comparing to several state‐of‐the‐arts(e.g.CGA,CMA‐IM,CIM,CDH‐SHRINK,CNCG,and CFIN).

CoxP@NiCo-LDH heteronanosheet arrays as efficient bifunctional electrocatalysts for co-generation of value-added formate and hydrogen with less-energy consumption

The inefficiency of water splitting is mainly due to the sluggish anodic water oxidation reaction. Replacing water oxidation with thermodynamically more favorable selective methanol oxidation reaction and developing robust bifunctional electrocatalysts are of great significance. Herein, a hierarchical heteronanostructure with Ni–Co layered double hydroxide(LDH) ultrathin nanosheets coated on cobalt phosphide nanosheets arrays(CoxP@NiCo-LDH) are fabricated and used for co-electrolysis of methanol/water to co-produce value-added formate and hydrogen with saving energy. Benefiting from the fast charge transfer introduced by phosphide nanoarrays, the synergy in nanosheets catalysts with hetero-interface,CoxP@NiCo-LDH/Ni foam(NF) exhibits superior electrocatalytic performance(10 mA cm-2@ 1.24 V and-0.10 V for methanol selective oxidation and hydrogen evolution reaction, respectively). Furthermore,CoxP@NiCo-LDH/NF-based symmetric two-electrode electrolyzer drives a current density of 10 m A cm-2 with a low cell voltage of only 1.43 V and the Faradaic efficiency towards the generation of formate and H2 are close to 100% in the tested range of current density(from 40 to 200 m A cm-2). This work highlights the positive effect of hetero-interaction in the design of more efficient eletrocatalysts and might guide the way towards facile upgrading of alcohols and energy-saving electrolytic H2 co-generation.

Effect of Cu loading content on the catalytic performance of Cu-USY catalysts for selective catalytic reduction of NO with NH_(3)

Series of Cu-USY zeolite catalyst with different Cu loading content were synthesized through simple impregnation method.The obtained catalysts were subjected to selective catalytic reduction of NOxwith NH_(3)(NH_(3)-SCR) performance evaluation,structural/chemical characterizations such as X-ray diffraction (XRD),N2adsorption/desorption,H_(2)temperature-programmed reduction (H_(2)-TPR),NH_(3)temperature-programmed desorption (NH_(3)-TPD) as well as detailed in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments including CO adsorption,NH_(3)adsorption and NO+O_(2)in situ reactions.Results show that Cu-USY with proper Cu loading (in this work 5Cu-USY with5 wt.%Cu) could be promising candidates with highly efficient NH_(3)-SCR catalytic performance,relatively low byproduct formation and excellent hydrothermal stability,although its SO_(2)poisoning tolerability needs alleviation.Further characterizations reveal that such catalytic advantages can be attributed to both active cu species and surface acid centers evolution modulated by Cu loading.On one hand,Cu species in the super cages of zeolites increases with higher Cu content and being more conducive for NH_(3)-SCR reactivity.On the other hand,higher Cu loading leads to depletion of Br?nsted acid centers and simultaneous formation of abundant Lewis acid centers,which facilitates NH_(4)NO_(3)reduction via NH_(3)adsorbed on Lewis acid centers,thus improving SCR reactivity.However,Cu over-introduction leads to formation of surface highly dispersed CuOx,causing unfavorable NH_(3)oxidation and inferior N2selectivity.

An Iron-Based High-Entropy Alloy with Highly Efficient Degradation for p-Nitrophenol

High-entropy alloys(HEAs)have attracted widespread attention due to their excellent mechanical properties.However,their functional properties arising from the supersaturated solid solution state can be improved.Advanced oxidation processes(AOPs)are considered to be an effective method for decomposing organic pollutants,and HEAs are proposed as effective candidates for AOP catalysts.Currently,several HEAs used for organic pollutant degradation are prepared through mechanical alloying.In this work,FeAlCoNi and FeAlCoNiB Fenton-like catalysts were prepared by single roll melt spinning and subsequent ball milling techniques.We found that the FeAlCoNiB HEA exhibits highly efficient degradation for p-nitrophenol(p-NP).The degradation efficiency of FeAlCoNiB is 120 times higher than that of FeAlCoNi,which confirms that boron functions effectively during the degradation process.FeAlCoNiB has a better degradation efficiency than pure iron powder and a degradation efficiency comparable to that of the amorphous Fe_(78)Si_(11)B_(11) alloy.Additionally,the degradation efficiency of FeAlCoNiB_(X) increases(k values from 0.13 to 0.55 min^(−1))when the boron content increases from an X value of 0.25 to 1.25.We speculate that Fe_(2)B favors the degradation process and promotes zero-valent iron to decompose organic pollutants through a galvanic cell effect.Possible p-NP degradation pathways are proposed after LC–MS analysis.This study provides a new series of HEA Fenton-like catalysts,which have the potential to be prepared into bulk devices for industrial applications.