Zephyranthes-like Co2NiSe4 arrays grown on 3D porous carbon frame-work as electrodes for advanced supercapacitors and sodium-ion batteries

Developing suitable electrode materials for electrochemical energy storage devices by biomorph assisted design has become a fascinating topic due to the fantastic properties derived from bio-architectures.Herein,zephyranthes-like Co_(2)NiSe_(4)arrays grown on butterfly wings derived three-dimensional(3D)carbon framework(Z-Co_(2)NiSe_(4)/BWC)is fabricated via hydrothermal assembly and further conversion method.Benefiting from its unique structure and multi-components,the obtained Z-Co_(2)NiSe_(4)/BWC electrode for supercapacitor delivers an excellent specific capacitance of 2,280 F·g^(-1)at 1 A·g^(-1).Impressively,the constructed asymmetric supercapacitor using Co_(2)NiSe_(4)/BWC as positive electrode and activated butterfly wings carbon as negative electrode acquires a high energy density of 42.9 Wh·kg^(-1)at a power density of 800 W·kg^(-1)with robust stability of 94.6%capacitance retention at 10 A·g^(-1)after 5,000 cycles.Moreover,the Z-Co_(2)NiSe_(4)/BWC as anode for sodium-ion batteries exhibits a high specific capacity of 568 mAh·g^(-1)at 0.1 A·g^(-1)and high cycling stability(maintaining 80.1%of the second cycle after 100 cycles).The outstanding electrochemical performances are ascribed to that the synergistic effect of bimetallic selenides and N-doped carbon improves electrochemical activities and conductivity.One-dimensional(1D)nanoneedles grown on 3D porous framework increase the exposure of redox-active sites,endow adequate transmission channels of electrons/ions,and guarantee stability of the electrode during charge/discharge processes.This study will shed light on the avenue towards extending such nanohybrids to excellent energy storage applications.

A channel-confined strategy for synthesizing CoN-CoO_(x)/C as efficient oxygen reduction electrocatalyst for advanced zinc-air batteries

Designing hybrid transition metal compounds with optimized electronic structure and firmly dispersing them on a matrix to avoid aggregation and shedding is of great significance for achieving high electrocatalytic performances.Herein,an adsorption-complexation-calcination strategy based on channel confining effect is explored to obtain CoN-CoO_(x)hybrid nanoparticles uniformly dispersed in mesoporous carbon.The CoN-CoO_(x)/C composite exhibits excellent electrocatalytic behavior for oxygen reduction reaction(ORR).The half-wave potential and durability are comparable or superior to those of Pt/C.When applying as cathode catalyst for a primary zinc-air battery,the open-circuit voltage and peak power density reach up to 1.394 V and 109.8 mW·cm^(−2),respectively.A high gravimetric energy density of 950.3 Wh·kgZn^(−1) is delivered at 10 mA·cm^(−2) with good rate capability and stability.Density functional theory(DFT)calculation demonstrates the favorable ORR intermediate adsorbability and metallic characteristics of CoN grains with oxide hybridization to optimize the electronic structure.This work provides a facile adjustable approach for obtaining highly dispersed nanoparticles with controllable hybrid composition on a substrate,which is important for future design and optimization of high-performance electrocatalysts.

Recent progress on preparation and applications of layered double hydroxides

The properties of layered double hydroxides(LDHs),including the adjustability of cations in host layers,exchangeability of anions between layers,and tunability of the crystal structure,render them unique characteristics in preparation and applications.Relating to the structural characteristics of LDHs,this work analyzes the research status,advantages and disadvantages of the synthetic methods for LDHs,including hydrothermal,electrodeposition,co-precipitation and anion exchange methods.In addition,the application status and prospects are reviewed,such as photo/electrocatalysis,electrochemical energy storage,magnetic materials,pollutant adsorption,and other fields.Lastly,the critical issues and solutions in the developing process of LDHs are analyzed and proposed.