Dual-functional ionic liquids additive enables dendrite-free Zn anode with ultra-long cycle life over one year.

Zn anodes suffer from the formation of uncontrolled dendrites aggravated by the uneven electric field and the insulating by-product accumulation in aqueous zinc-ion batteries (AZIBs). Here, an effective strategy implemented by 1-butyl-3-methylimidazolium hydrogen sulfate (BMIHSO4) additive is proposed to synergistically tune the crystallographic orientation of zinc deposition and suppress the formation of zinc hydroxide sulfate for enhancing the reversibility on Zn anode surface. As a competing cation, BMI+ is proved to preferably adsorb on Zn-electrode compared with H2O molecules, which shields the "tip effect" and inhibits the Zn-deposition agglomerations to inducing the horizontal growth along Zn (002) crystallographic texture. Simultaneously, the protonated BMIHSO4 additives could remove the detrimental OH- in real-time to fundamentally eliminate the accumulation of 6Zn(OH)2·ZnSO4·4H2O and Zn4SO4(OH)6·H2O on Zn anode surface. Consequently, Zn anode exhibits an ultra-long cycling stability of one year (8762 h) at 0.2 mA cm-2/0.2 mAh cm-2, 3600 h at 2 mA cm-2/2 mAh cm-2 with a high plating cumulative capacity of 3.6 Ah cm-2, and a high average Coulombic efficiency of 99.6 % throughout 1000 cycles. This work of regulating Zn deposition texture combined with eliminating notorious by-products could offer a desirable way for stabilizing the Zn-anode/electrolyte interface in AZIBs.

Efficient C2H2-selective separation in a microporous Zn(II)-based metal-organic framework via the dual-ligand strategy.

Implementing the dual-ligand strategy, a microporous Zn-based MOF 1 with nitro and amino groups was effectively produced. The activated interconnected pores of 1 exhibited high C2H2 uptake capacity and preferential adsorption behaviour for C2H2 over CO2, as identified by the experiments and simulations. This work provides a new approach for designing and synthesizing the MOFs with desired structures and properties by optimizing their pore environment via the dual-ligand strategy.

Coral-like Fe-doped MoO2/C heterostructures with rich oxygen vacancies for efficient electrocatalytic N2 reduction.

Molybdenum (Mo) is one of the most important constituent elements in natural nitrogenase and theoretical calculation results show that Mo-based materials can be used as potential NRR electrocatalysts. The design of advanced catalysts with a special structure is very essential for promoting the development of electrocatalytic N2 into NH3. In this paper, Fe-doped MoO2/C heterostructured nanoparticles with rich oxygen vacancies (Vo) are designed and they exhibit highly efficient catalytic activity for artificial N2 fixation in neutral electrolytes under ambient conditions. The influence of the atomic ratio of the Fe source to the Mo source and the NaBH4 ethanol solution treatment on the structure and electrocatalytic performance are systematically investigated. The Vo-Fe-MoO2/C (1 : 50) catalyst with rich oxygen vacancies shows a satisfactory electrocatalytic N2 reduction reaction (e-NRR) activity in 0.1 M Na2SO4 with a high ammonia yield rate of 15.87 ± 0.3 µg h-1 mg-1 at -0.5 V versus the reversible hydrogen electrode (vs. the RHE) and a FE of 13.4% at -0.3 V (vs. the RHE). According to the results of DFT calculations, the active center of the electro-catalytic nitrogen reduction reaction is the molybdenum atom between the iron atom and the O vacancy. Oxygen vacancies can not only reduce the energy barrier of the RDS but also facilitate the desorption of ammonia and the first step hydrogenation of nitrogen. The doping of Fe will change the electronic state of the Mo atom in MoO2.

Electro-wetting of a nanoscale water droplet on a polar solid surface in electric fields.

Molecular dynamics simulations were applied to study the wetting properties of nanoscale droplets on a polar silica solid substrate subjected to constant and alternative electric fields with various field frequencies. Results show that the external applied electric fields have significant effects on the wetting of the nanoscale droplet on a polar solid substrate. The droplet spreads asymmetrically under the effect of the external applied field, and this asymmetry culminates to the maximum when the electric field equals to 0.45 V nm-1. For an electric field of 1.0 V nm-1, the dynamic electro-wetting process undergoes two stages even with a symmetric equilibrium spreading state. The stage A-B transition happens suddenly when molecules on the leading edge drop onto the solid surface due to the strong attraction of the solid substrate. Furthermore, under the alternative electric field with a different GHz frequency range, it was observed that the spreading asymmetry was weakened by increasing the field frequency and the nanoscale water droplet shape changes very slightly above a threshold frequency. Accompanied by the shape variation of water droplets, the molecular dipole orientations of water molecules experience a remarkable change from a random disordered distribution to an ordered profile because of the realignment of water molecules induced by electric fields. In addition, the polar solid surface has significant effects on the rearrangement of water molecules compared with a single droplet. Thus, the electro-wetting behaviors of water droplets on a silica solid surface are determined by the competing intermolecular forces among water, solid and the electric field.

Mechanical properties of hollow and water-filled graphyne nanotube and carbon nanotube hybrid structure.

By performing molecular dynamics simulations, a GNT/CNT hybrid structure constructed via combing (6, 6) graphyne nanotube (GNT) with (6, 6) carbon nanotube (CNT) has been designed and investigated. The mechanical properties induced by the percentage of GNT, water content and electric field were examined. Calculation results reveal that the fracture strain and strength of hollow hybrid structure are remarkably smaller than that of perfect (6, 6) CNT. In addition, the Young's modulus decreases monotonously with the increase of percentage of GNT. More importantly, the tunable mechanical properties of hybrid structure can be achieved through filling with water molecules and applying an electric field along tensile direction. Specifically, increasing water content from 0.0 to 8.70 mmol g-1 in the absence of electric field could result in fracture strain and strength reducing by 15.09% and 12.87%, respectively. Besides, enhancing fracture strain and strength of water-filled hybrid structure with water content of 8.70 mmol g-1 can also be obtained with rising electric field intensity. These findings would provide a valuable theoretical basis for designing and fabricating a nanodevice with controllable mechanical performances.