Constructing ultrafine monodispersed Co_(2)P/(0.59-Cu_(3)P)on Cu doped CoZn-ZIF derived porous N-doped carbon for highly efficient dehydrogenation of ammonia borane

Rational construction of highly dispersed,small size,low cost catalysts for release of hydrogen from ammonia borane(AB)is regarded as a prospective approach for promoting the development of upcoming hydrogen economy.However,the high price and scarcity of precious metal catalysts impose restrictions on their large-scale application.To this end,with the aid of a Cu doped CoZn-zeolitic imidazolate frameworks(ZIFs)template strategy,we successfully construct ultrafine monodispersed Co_(2)P/(0.59-Cu_(3)P)on CoZn-ZIF derived porous N-doped carbon(Co_(2)P/(0.59-Cu_(3)P)-NC)as an efficient non-noble-metal catalyst.Specifically,Co and Cu atoms can be geometrically separated to high degree due to the presence of Zn in the CuCoZn-ZIF precursor,evaporation of Zn during pyrolysis can generate porous structure with the framework well maintained.The results show that porous Co_(2)P/(0.59-Cu_(3)P)-NC bimetallic phosphide exhibits large specific surface area,hierarchical pore structure,well-exposed active sites.Based on the kinetics analyses and ion effects,the catalyst has achieved an unprecedentedly high total turnover frequency(TOF)of 798 mol·molcat^(−1)·min^(−1)in 0.4 M NaOH solution at 298 K,which surpasses all the ever-reported transition-metal phosphides catalysts for hydrogen generation from AB.Experiments and theoretical studies confirm that the highly porous structure of the support,the ultrafine and high dispersion of nanoparticles,the N/P doping and their synergistic effects(e.g.,M-P,M-N,N-C,M-M',M-support)jointly induce strong electron transfer,which can reduce the reaction energy barrier and enhance their interaction with AB,thus correspondingly obtaining excellent catalytic performance.The mechanism and strategy presented in this work pave an avenue for the design of non-noble metal catalyst for hydrogen energy system.

Consideration on aircraft tire spray when running on wet runways

The tire spray produced by aircraft running on wet runways may enter the intake of engines,which may lead to the compressor stall,surge,or even combustion flameout.Therefore,it is necessary to do some research work on the tire spray to help to solve this problem.Firstly,the mechanism of tire spray is analyzed,and some parameters are defined to describe the spray pattern.Secondly,the numerical model of tire spray is established by coupled Smoothed Particle Hydrodynamics(SPH)and Finite Element Method(FEM)in LS-DYNA software,and the model is validated by a simplified water spray experiment.Then some influence factors on the spray pattern are studied by numerical simulation.Finally,some suggestions are proposed on different types of aircraft to avoid too much tire spray being ingested into the engine intakes.

SE2IR Invest Market Rumor Spreading Model Considering Hesitating Mechanism

According to the actual situation of investor network, a SE2IR rumor spreading model with hesitating mechanism is proposed, and the corresponding mean-?eld equations is obtained on scale-free network. In this paper, we ?rst combine the theory of spreading dynamics and ?nd out the basic reproductive number R0. And then analyzes the stability of the rumor-free equilibrium and the?nal rumor size. Finally, we discuss random immune strategies and target immune strategies for the rumor spreading, respectively. Through numerical simulation, we can draw the following conclusions:Reducing the fuzziness and attractiveness of invest market rumor can effectively reduce the impact of rumor. And the target immunization strategy is more effective than the random immunization strategy for the communicators in the invest investor network.