摘要
Electrocatalysis is key to improving energy efficiency,reducing carbon emissions,and providing a sustainable way of meeting global energy needs.Therefore,elucidating electrochemical reaction mechanisms at the electrolyte/electrode interfaces is essential for developing advanced renewable energy technologies.However,the direct probing of real-time interfacial changes,i.e.,the surface intermediates,chemical environment,and electronic structure,under operating conditions is challenging and necessitates the use of in situ methods.Herein,we present a new lab-based instrument commissioned to perform in situ chemical analysis at liquid/solid interfaces using ambient pressure X-ray photoelectron spectroscopy(APXPS).This setup takes advantage of a chromium source of tender X-rays and is designed to study liquid/solid interfaces by the“dip and pull”method.Each of the main components was carefully described,and the results of performance tests are presented.Using a three-electrode setup,the system can probe the intermediate species and potential shifts across the liquid electrolyte/solid electrode interface.In addition,we demonstrate how this system allows the study of interfacial changes at gas/solid interfaces using a case study:a sodium–oxygen model battery.However,the use of APXPS in electrochemical studies is still in the early stages,so we summarize the current challenges and some developmental frontiers.Despite the challenges,we expect that joint efforts to improve instruments and the electrochemical setup will enable us to obtain a better understanding of the composition–reactivity relationship at electrochemical interfaces under realistic reaction conditions.
在“双碳”目标背景下,推进产业和能源结构调整,发展可再生能源和提高能源利用效率成为当务之急.电催化在提高能源效率、减少碳排放和实现全球能源体系的可持续发展中扮演重要角色.阐明电解质/电极界面的反应机制是从原子分子层面理解电催化反应机理的前提,对于理性合成高效催化剂以及开发先进可再生能源技术至关重要.在界面反应机制的研究中,一项关键要求是如何在工况条件下原位探测界面处的反应中间体、化学环境和电子结构的实时变化.该要求对传统的X射线电子谱学实验方法提出了挑战.由于传统的X射线电子能谱需要在超高真空的环境中开展实验,导致该技术很难直接应用于电催化反应条件下的表征.为了克服这一难题,本文发展了用于电化学体系中液/固和气/固界面原位探测的实验室近常压光电子能谱.该装置利用中能X射线(金属Cr的Kα发射谱线,能量5.4 keV)作为激发光源,配备HiPP-2电子能量分析器.为满足电化学体系研究,整套系统采用紧凑型设计,通过分析测试腔体将X光源和电子能量分析器相连.该近常压X光电子能谱仪的工作压力为30 Torr(室温下水的饱和蒸汽压为20 Torr),可以直接将电化学溶液体系放入测试腔体.分析测试腔体配备快门,通过X射线窗口和分析器挡板,可在不影响X光源和分析器真空的条件下快速更换研究体系.通过原位样品杆的设计,满足电化学三电极装置在测试腔体内的使用.借助“浸-拉”方法在工作电极表面制备10纳米量级的连续液膜,从而实现液/固界面的探测.通过使用三电极装置,该近常压光电子能谱系统可以表征电极表面物种、电解液以及电解液/电极界面随电位的变化.此外,还通过对钠氧模型电池的研究,展示了该系统如何探测气/固界面在电化学反应中的变化.本文还总结了当前在电化学研究中应用近常压光电子能谱的一些挑战和发展前沿,期望通过仪器研发和电化学研究两个领域科学家的共同努力,为现实反应条件下电化学界面的组成-反应性能关系的理解做出贡献.
基金
国家自然科学基金(21832004,21802096,22072093,21902179,21991152,21991150,11227902)
上海市青年科技启明星计划(21QA1406200)
上海市科学技术委员会(14520722100)
活细胞结构与功能成像等线站工程(31011505505885920161A2101001).
