Discrete Particle Simulation of Gas-Solid Flow in Air-Blowing Seed Metering Device

In this paper,the gas and seed flow characters in the air-blowing seed metering device are investigated by using the coupled computational fluid dynamics and discrete element method(CFD-DEM)in three dimensions(3D).The method of establishing boundary model based on the computer-aided design(CAD)drawing,has been used to build the boundary model of seed metering device.The 3D laser scanning technique and multi-element method are adopted to establish the particle model.Through a combined numerical and experimental effort,using 3D CFD-DEM software,which is based on the in-house codes,the mechanisms governing the gas and solid dynamic behaviors in the seed metering device have been studied.The gas velocity field and the effect of different rotational speeds and air pressures on the seeding performance and particle velocity have been studied,similar agreements between numerical and experimental results are gained.This reveals that the 3D CFD-DEM model established is able to predict the performance of the air-blowing seed metering device.It can be used to design and optimize the air-blowing seed metering device and other similar agriculture devices.

NiCoP nanoleaves array for electrocatalytic alkaline H2 evolution and overall water splitting

The development of non-precious, high-efficient and durable electrocatalysts for H2 evolution in alkaline media is highly desirable. Herein we report NiCoP nanoleaves array vertically grown on Ni foam for H2 evolution and overall water splitting via simple hydrothermal treatment and phosphorization. The selfsupported NiCoP nanoleaves architecture contributes to more exposed active sites, the smaller contact resistance between catalyst and substrate, faster ion diffusion and electron transfer. As a result, the optimized electrode requires only overpotentials of 98 and 173 mV to achieve current densities of 10 and100 m A cm-2 in 1.0 M KOH,respectively. Besides, used as both anode and cathode simultaneously, the electrode delivers current densities of 100 and 200 m A cm-2 at cell voltages of only 1.8 and 1.87 V, respectively. Moreover, the relatively high efficiency of about 11.4% for solar-driven water splitting further illustrates the application of our catalyst to sustainable development based on green technologies.

Highly efficient oxygen evolution and stable water splitting by coupling NiFe LDH with metal phosphides

It is a great challenge to develop highly active oxygen evolution reaction(OER)electrocatalysts with superior durability.In this study,a NiFe layered double hydroxidedecorated phosphide(NiFe LDH@CoP/NiP_(3))was constructed to display satisfactory OER activity and good stability for water splitting in alkaline media.At an overpotential of 300 mV,NiFe LDH@CoP/NiP_(3) achieved a current density of 82 mA cm^(-2) for the OER,which was 9.1 and 2.3 times that of CoP/NiP_(3) and NiFe LDH,respectively.Moreover,the reconstruction behavior,during which oxyhydroxides formed,was studied by a combination of X-ray photoelectron spectroscopy,Raman spectroscopy,and scanning electron microscopy.A synergistic effect between NiFe LDH and CoP/NiP_(3) was also observed for the hydrogen evolution reaction.Furthermore,when NiFe LDH@CoP/NiP_(3) acted as both the cathode and anode for overall water splitting,a high current density of 100 mA cm^(-2) was maintained for more than 275 h.In addition,under Xe light irradiation,a solar-to-hydrogen efficiency of 9.89% was achieved for solar-driven water splitting.This work presents the coupling of different active compositions,and can provide a reference for designing bifunctional electrocatalysts.

Bimetallic chalcogenides for electrocatalytic CO_(2)reduction

Electrocatalytic CO_(2)reduction reaction(CO_(2)RR)converts CO_(2)into valuable chemical fuels,which can effectively alleviate global warming and energy crisis.However,limited by its slow reaction rate and low product selectivity,it is urgent to design efficient,cheap,safe,and highly selective CO_(2)RR electrocatalysts.Owing to the advantages of adjustable electronic structure,abundant active sites,low cost,environmental friendliness and excellent electrochemical performance,bimetallic chalcogenides have aroused great interest.Here,we briefly summarized different bimetallic oxides and sulfides for electrocatalytic CO_(2)RR in the past five years.In addition,different hybridizations formed between metal atoms,including intermetallic compounds,heterostructures and metal doping,were generalized.Their positive effects on CO_(2)RR catalytic selectivity and activity were deeply uncovered.Besides,we also put forward some views about the future research directions and perspectives in CO_(2)RR field.This review aims to provide a reference for the rational design of bimetallic chalcogenides towards electrocatalytic CO_(2)reduction.

Z-scheme systems of ASi_(2)N_4(A=Mo or W)for photocatalytic water splitting and nanogenerators

Z-scheme heterojunction catalysts have received great attention due to their efficient ability to separate electrons and holes.Here,using the first-principles calculations,we designed a series of promising two-dimensional(2D)/2D Z-scheme systems with interlayer inequivalent,including MoSi_(2)N_(4)/MoSi_(2)N_(4),WSi_(2)N_(4)/WSi_(2)N_(4) and MoSi_(2)N_(4)/WSi_(2)N_(4).Molecular dynamics simulation and phonon dispersion show that they have sufficient environmental stability.The inequivalent structure between the layers caused the directional formation of built-in potentials,driving the transfer of net charge between layers,which greatly enhanced their catalytic activity.The smaller band gap and enhanced light absorption performance further revealed their perfect catalytic performance.Moreover,all they met the redox potential requirements of water splitting in a range of pH 0-7,demonstrate they are very remarkable photocatalysts for H_(2)evolution.More interestingly,they also have good sliding ferroelectricity,and the opposite built-in potential can be obtained by sliding between layers,which is very promising for future nanogenerators.Our works may provide new insights into energy conversion devices.

Phosphating-induced charge transfer on CoO/CoP interface for alkaline H_(2)evolution

Designing non-noble metal electrocatalysts toward alkaline hydrogen evolution reaction(HER)with high performance at a large current density is urgent.Herein,a CoO/CoP heterostructure catalyst(termed POZ)was designed by a phosphating strategy.The strong electron transfer on the interface of CoO/CoP was experimentally and theoretically proven.POZ showed a low overpotential of 236 mV at 400 mA/cm^(2),which was 249 mV lower than non-phosphated sample.It also exhibited a remarkable solar-to-hydrogen conversion efficiency of 10.5%.In this work,the construction of CoO/CoP interface realized by a simple phosphating strategy could provide an important reference to boost the HER performance on those materials not merely metal oxides.

Multifunctional silicene/CeO_(2)heterojunctions:Desirable electronic material and promising water-splitting photocatalyst

The first-principles calculations demonstrate that covalently bonded(cb)heterojunction and van der Waals(vd W)heterojunction can coexist in silicene/CeO_(2) heterojunctions,due to the different stacking patterns.Especially,the cb heterojunction with band gap of 1.97 e V,forms a type-II heterojunction,exhibits good redox performance and has high-effective optical absorption spectra,thus it is a promising photocatalyst for overall water splitting.Besides,for the vd W heterojunction,the Dirac cone of silicene is well kept on CeO_(2) semiconducting substrate,with a considerable energy gap of 0.43 e V,which can be an ideal material in building silicene-based electronic device.These results may open a new gateway in both of nanoelectronic device and energy conversion for silicene/Ce O2 nanocomposites.