Microwave-assisted exploration of the electron configuration-dependent electrocatalytic urea oxidation activity of 2D porous NiCo_(2)O_(4) spinel

Urea holds promise as an alternative water-oxidation substrate in electrolytic cells.High-valence nickelbased spinel,especially after heteroatom doping,excels in urea oxidation reactions(UOR).However,traditional spinel synthesis methods with prolonged high-temperature reactions lack kinetic precision,hindering the balance between controlled doping and highly active two-dimensional(2D)porous structures design.This significantly impedes the identification of electron configuration-dependent active sites in doped 2D nickel-based spinels.Herein,we present a microwave shock method for the preparation of 2D porous NiCo_(2)O_(4)spinel.Utilizing the transient on-off property of microwave pulses for precise heteroatom doping and 2D porous structural design,non-metal doping(boron,phosphorus,and sulfur)with distinct extranuclear electron disparities serves as straightforward examples for investigation.Precise tuning of lattice parameter reveals the impact of covalent bond strength on NiCo_(2)O_(4)structural stability.The introduced defect levels induce unpaired d-electrons in transition metals,enhancing the adsorption of electron-donating amino groups in urea molecules.Simultaneously,Bode plots confirm the impact mechanism of rapid electron migration caused by reduced band gaps on UOR activity.The prepared phosphorus-doped 2D porous NiCo_(2)O_(4),with optimal electron configuration control,outperforms most reported spinels.This controlled modification strategy advances understanding theoretical structure-activity mechanisms of high-performance 2D spinels in UOR.

Microwave shock motivating the Sr substitution of 2D porous GdFeO_(3) perovskite for highly active oxygen evolution

The incorporation of partial A-site substitution in perovskite oxides represents a promising strategy for precisely controlling the electronic configuration and enhancing its intrinsic catalytic activity.Conventional methods for A-site substitution typically involve prolonged high-temperature processes.While these processes promote the development of unique nanostructures with highly exposed active sites,they often result in the uncontrolled configuration of introduced elements.Herein,we present a novel approach for synthesizing two-dimensional(2D)porous GdFeO_(3) perovskite with A-site strontium(Sr)substitution utilizing microwave shock method.This technique enables precise control of the Sr content and simultaneous construction of 2D porous structures in one step,capitalizing on the advantages of rapid heating and cooling(temperature~1100 K,rate~70 K s^(-1)).The active sites of this oxygen-rich defect structure can be clearly revealed through the simulation of the electronic configuration and the comprehensive analysis of the crystal structure.For electrocatalytic oxygen evolution reaction application,the synthesized 2D porous Gd_(0.8)Sr_(0.2)FeO_(3) electrocatalyst exhibits an exceptional overpotential of 294 mV at a current density of 10 mA cm^(-2)and a small Tafel slope of 55.85 mV dec^(-1)in alkaline electrolytes.This study offers a fresh perspective on designing crystal configurations and the construction of nanostructures in perovskite.

微波热冲快速制备二维多孔La_(0.2)Sr_(0.8)CoO_(3)钙钛矿用于高效电催化析氧反应

析氧反应(OER)被认为是电解水的关键限制步骤,已被广泛作为清洁能源方式用于解决能源和环境问题。钙钛矿氧化物(ABO_(3))具有可调的电子结构、高灵活性的元素组成,能在OER中表现出良好的催化活性。然而,钙钛矿氧化物的合成通常需要经历长时间的高温,极易导致金属的聚集和影响材料的本征活性。气相微波技术可以显著缩短热处理时间,从而减少相关的碳排放。这项技术不仅解决了对碳中性过程日益增长的需求,而且还增加了对合成的控制,以避免产品的不良团聚。本文采用微波热冲法快速制备了二维(2D)多孔La_(0.2)Sr_(0.8)CoO_(3)钙钛矿。伴随微波过程的快速熵增可以有效地暴露La_(0.2)Sr_(0.8)CoO_(3)结构中丰富的活性位点。此外,高能微波冲击过程可以精准地将Sr2+引入到LaCoO_(3)的晶格中,通过增加Co的氧化态来增加氧空位量。这种锶元素取代镧引入的氧空位能极大提高催化剂的本征催化活性。对于碱性电解液中的OER应用,制备的La_(0.2)Sr_(0.8)CoO_(3)在10 m A·cm^(-2)下展现出了360 m V的过电位,Tafel斜率为76.6 mV·dec^(-1)。且在经历30000秒的长时间循环测试后仍能维持初始电流密度的97%。这项研究为高活性二维钙钛矿的合成提供了一种简便、快速的策略。

Free-standing Na_(2)C_(6)O_(6)/MXene composite paper for highperformance organic sodium-ion batteries

Sodium-ion batteries(SIBs)are regarded as the ideal low-cost choice for next-generation large-scale energy storage system.Carbonyl-based organic salt-disodium rhodizonate(Na_(2)C_(6)O_(6))with high theoretical specific capacity(501 mAh·g−1)is considered as a promising cathode material for SIBs.However,the dissolution of active material in electrolyte and low electronic conductivity lead to rapidly capacity decay and poor rate performance.Herein,a simple method is designed to construct free-standing and flexible Ti3C2Tx Na2C6O6/MXene paper via vacuum-assisted filtration and antisolvent approach.The MXene can form an electronic conductive network,adsorb the active materials,and offer additional active sites for Na storage.The binder-free Na_(2)C_(6)O_(6)/MXene paper delivers excellent electrochemical property with a high rate performance of 231 mAh·g−1 at 1,000 mA·g−1 and a high capacity of 215 mAh·g−1 after 100 cycles.This work provides an attractive strategy for designing high-performance organic electrode materials of SIBs.

Room-temperature liquid metal engineered iron current collector enables stable and dendrite-free sodium metal batteries in carbonate electrolytes

Metallic sodium(Na)is believed to be a promising anode material for sodium-ion batteries(SIBs)due to its low electrochemical potential,high theoretical specific capacity,superior electrical conductivity,and so on.However,issues such as high chemical activity,the growth of Na dendrites,large volume change,and unstable interface impede its practical application.We design a cheap iron(Fe)-based substrate decorated by a thin liquid metal Ga layer for stable and dendrite-free Na metal anodes in low-cost carbonate electrolytes.The inherent mechanism of Ga-based liquid metal in inhibiting the growth of Na dendrites was revealed for the first time.Liquid metal Ga with sodiophilic property can act as nucleation seeds to decrease the nucleation barrier and induce homogeneous Na+flux,resulting in uniform and dendrite-free Na deposition.Full cells with Na_(3)V_(2)(PO_(4))_(3) cathode were also assembled to verify the practical application ability of the modified Na metal anode.Under the regulation of the liquid metal layer,the Coulombic efficiency,cycling life,and capacity of batteries are obviously enhanced.The strategy proposed here cannot only reduce the cost of batteries but also improve their electrochemical and safety performance.