Lopez-Astacio Hiram, Vargas-Perez Brenda Lee, Del Valle-Perez Angelica, Pollock Christopher J, Cunci Lisandro
Department of Chemistry and Physics, Universidad Ana G. Mendez at Gurabo, Gurabo, Puerto Rico, USA.
Department of Chemistry, University of Puerto Rico at Rio Piedras, San Juan, Puerto Rico, USA.
J Synchrotron Radiat. 2024 Mar 1;31(Pt 2):322-327. doi: 10.1107/S1600577524000122. Epub 2024 Feb 2.
X-ray spectroscopy is a valuable technique for the study of many materials systems. Characterizing reactions in situ and operando can reveal complex reaction kinetics, which is crucial to understanding active site composition and reaction mechanisms. In this project, the design, fabrication and testing of an open-source and easy-to-fabricate electrochemical cell for in situ electrochemistry compatible with X-ray absorption spectroscopy in both transmission and fluorescence modes are accomplished via windows with large opening angles on both the upstream and downstream sides of the cell. Using a hobbyist computer numerical control machine and free 3D CAD software, anyone can make a reliable electrochemical cell using this design. Onion-like carbon nanoparticles, with a 1:3 iron-to-cobalt ratio, were drop-coated onto carbon paper for testing in situ X-ray absorption spectroscopy. Cyclic voltammetry of the carbon paper showed the expected behavior, with no increased ohmic drop, even in sandwiched cells. Chronoamperometry was used to apply 0.4 V versus reversible hydrogen electrode, with and without 15 min of oxygen purging to ensure that the electrochemical cell does not provide any artefacts due to gas purging. The XANES and EXAFS spectra showed no differences with and without oxygen, as expected at 0.4 V, without any artefacts due to gas purging. The development of this open-source electrochemical cell design allows for improved collection of in situ X-ray absorption spectroscopy data and enables researchers to perform both transmission and fluorescence simultaneously. It additionally addresses key practical considerations including gas purging, reduced ionic resistance and leak prevention.
X射线光谱学是研究许多材料体系的一种有价值的技术。原位和实时表征反应可以揭示复杂的反应动力学，这对于理解活性位点组成和反应机理至关重要。在本项目中，通过在电池上下游两侧具有大开口角的窗口，完成了一种开源且易于制造的电化学电池的设计、制造和测试，该电池用于与透射和荧光模式下的X射线吸收光谱兼容的原位电化学。使用业余爱好者的计算机数控机器和免费的三维计算机辅助设计软件，任何人都可以利用这种设计制造出一个可靠的电化学电池。将铁钴比为1:3的洋葱状碳纳米颗粒滴涂在碳纸上，用于原位X射线吸收光谱测试。碳纸的循环伏安法显示出预期的行为，即使在夹层电池中，欧姆降也没有增加。计时电流法用于施加相对于可逆氢电极0.4 V的电压，有和没有进行15分钟的氧气吹扫，以确保电化学电池不会由于气体吹扫而产生任何假象。正如在0.4 V时所预期的那样，X射线吸收近边结构（XANES）和扩展X射线吸收精细结构（EXAFS）光谱在有和没有氧气的情况下均未显示出差异，并且没有由于气体吹扫而产生的任何假象。这种开源电化学电池设计的开发有助于改进原位X射线吸收光谱数据的收集，并使研究人员能够同时进行透射和荧光测试。它还解决了包括气体吹扫、降低离子电阻和防止泄漏等关键实际问题。
