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

Microwave Shock Process for Rapid Synthesis of 2D Porous La_(0.2)Sr_(0.8)CoO_(3)Perovskite as an Efficient Oxygen Evolution Reaction Catalyst

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。

The oxygen evolution reaction(OER)is considered the rate-limiting step in electrochemical water splitting,and has been widely used to solve energy and environmental issues.Perovskite oxides(ABO_(3))exhibit good OER activity,owing to their tunable electronic structures and highly flexible elemental compositions.However,the preparation of perovskite oxides usually requires long exposure to high temperatures,resulting in metal agglomeration and undesirable effects on intrinsic activity.Vapor-phase microwave technology can significantly reduce the duration of heat treatment and subsequently reduce the associated carbon emissions.This technology not only addresses the growing demand for carbon-neutral processes but also enables increased control of the synthesis to avoid undesirable agglomeration of the product.In this study,a 2D porous La_(0.2)Sr_(0.8)CoO_(3)perovskite was rapidly prepared using a microwave shock method.The rapid entropy increase associated with the microwave process can effectively expose abundant active sites in the La_(0.2)Sr_(0.8)CoO_(3)structure.Furthermore,the high-energy microwave shock process can precisely introduce Sr2+into the lattice of LaCoO_(3),increasing the number of oxygen vacancies by increasing the oxidation state of Co.The oxygen vacancies introduced by replacing La with Sr can considerably improve the intrinsic catalytic activity of the material.For the OER in alkaline electrolytes,the prepared La_(0.2)Sr_(0.8)CoO_(3)catalyst displayed an excellent overpotential of 360 mV at 10 mA·cm^(−2)and a Tafel slope of 76.6 mV·dec^(−1).After a long-term cycle test of 30000 s,97%of the initial current density was maintained.This study presents a facile and rapid strategy for the synthesis of highly active 2D perovskites.