Quasi‑Solid Electrolyte Interphase Boosting Charge and Mass Transfer for Dendrite‑Free Zinc Battery

The practical applications of zinc metal batteries are plagued by the dendritic propagation of its metal anodes due to the limited transfer rate of charge and mass at the electrode/electrolyte interphase.To enhance the reversibility of Zn metal,a quasi-solid interphase composed by defective metal-organic framework(MOF)nanoparticles(D-UiO-66)and two kinds of zinc salts electrolytes is fabricated on the Zn surface served as a zinc ions reservoir.Particularly,anions in the aqueous electrolytes could be spontaneously anchored onto the Lewis acidic sites in defective MOF channels.With the synergistic effect between the MOF channels and the anchored anions,Zn^(2+)transport is prompted significantly.Simultaneously,such quasi-solid interphase boost charge and mass transfer of Zn^(2+),leading to a high zinc transference number,good ionic conductivity,and high Zn^(2+)concentration near the anode,which mitigates Zn dendrite growth obviously.Encouragingly,unprecedented average coulombic efficiency of 99.8%is achieved in the Zn||Cu cell with the proposed quasi-solid interphase.The cycling performance of D-UiO-66@Zn||MnO_(2)(~92.9%capacity retention after 2000 cycles)and D-UiO-66@Zn||NH_(4)V_(4)O_(10)(~84.0%capacity retention after 800 cycles)prove the feasibility of the quasi-solid interphase.

Electrocaloric effect in ferroelectric materials:From phase field to first-principles based effective Hamiltonian modeling

Electrocaloric effect(ECE)of ferroelectrics has attracted considerable interest due to its potential application in environmentally friendly solid-state refrigeration.The discovery of giant ECE in ferroelectric thin films has greatly renewed the research activities and significantly stimulated experimental and theoretical investigations.In this review,the recent progress on the theoretical modeling of ECE in ferroelectric and antiferroelectric materials are introduced,which mainly focuses on the phase field modeling and first-principles based effective Hamiltonian method.We firstly provide the theoretical foundation and technique details for each method.Then a comprehensive review on the progress in the application of two methods and the strategies to tune the ECE are presented.Finally,we outline the practical procedure on the development of multi-scale computational method without experiemtal parameters for the screening of optimized electrocaloric materials.

Intrinsic ferroelectrics and carrier doping-induced metallic multiferroics in an atomic wire

Low-dimensional multiferroic metals characterized by the simultaneous coexistence of ferroelectricity,conductivity,and magnetism hold tremendous potential for scientific and technological endeavors.However,the mutually exclusive mechanisms among these properties impede the discovery of multifunctional conducting multiferroics,especially at the atomic-scale.Here,based on first-principles calculations,we design and demonstrate intrinsic one-dimensional(1D)ferroelectrics and carrier dopinginduced metallic multiferroics in an atomicWOF4 wire.TheWOF4 atomic wire that can be derived from a 1D van derWaals crystal exhibits pronounced ferroelectricity manifested in the form of large cooperative atomic displacements.By performing Monte Carlo simulations with an effective Hamiltonian method,we obtain the nanowire that can sustain a high Curie temperature,indicating its potential for roomtemperature applications.Moreover,doping with electrons is found to induce magnetism and metallic conductivity that coexists with the ferroelectric distortion in the nanowire.These appealing properties in conjunction with the experimental feasibility enable the doped WOF4 nanowire to act as a promising atomic-scale multifunctional material.

1T@2H-MoSe2 nanosheets directly arrayed on Ti plate： An efficient electrocatalytic electrode for hydrogen evolution reaction

Few-layered MoSe2 nanosheets with mixed 1T/2H phase were successfully arrayed on a Ti substrate （forming 1T@2H-MoSe2/Ti） through a facile one-step solvothermal process. After testing different synthesis conditions, it was found that the optimal process involves a temperature of 200℃ and a reaction time of 12 h. Structural characterizations reveal that the morphology of 1T@2H-MoSe2 consists of edge- terminated nanosheets with one to five layers, composed of a mixed 1T/2H phase dominated by the 1T one. The 1T@2H-MoSe2/Ti electrode shows excellent HER catalytic activity, with a small onset potential （-120 mV vs. reversible hydrogen electrode, RHE） and an electrode potential of only -133 mV （vs. RHE） to achieve a current density of 20 mA·cm^-2. This excellent electrocatalytic activity is due to the synergistic effects of 1T metallic phase, few-layered nanosheet morphology, and direct growth of 1T@2H-MoSe2 on the Ti substrate. In addition, the 1T@2H-MoSe2/Ti electrode shows excellent stability towards long-term electrolysis. This is due to the long-term stability of the valence states of Mo and Se, as shown by post-electrolysis X-ray photoelectron spectroscopy analysis.