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析氧电催化剂的相关operando显微镜研究
作者:小柯机器人 发布时间:2021/5/8 16:43:37

美国斯坦福大学William C. Chueh小组近日取得一项新成果。经过不懈努力,他们提出了对析氧电催化剂的相关operando显微镜观察。 相关论文于2021年5月5日发表在《自然》杂志上。

该工作中,研究人员利用一系列相关operando扫描探针和x射线显微技术,建立了单晶β-Co(OH)2小型板状颗粒的局部操作化学、物理和电子纳米级结构与析氧活性之间的联系。在预催化电压下,粒子膨胀形成α-CoO2H1.5·0.5 H2O样结构(通过氢氧根插层产生),钴的氧化态为+2.5。在增加电压以驱动氧气逸出后,层间水和质子脱嵌,形成含有Co3+物种的收缩的β-CoOOH颗粒。

虽然这些转变通过大量粒子体表现为异质相变,但电化学电流主要局限于它们的边缘面。观察到的Tafel行为与这些反应边缘位点Co3+的局部浓度相关,表明了大量离子插入和表面催化活性之间的联系。

据悉,过渡金属(氧)氢氧化物是用于氧释放反应的有前途的电催化剂。这些材料的性质随外加电压通过离子插入氧化还原反应动态地和异质性地演化,在操作过程中将开路条件下不活跃的材料转化为活性电催化剂。催化状态本身就远离平衡状态,这使得直接观察它变得复杂。

附:英文原文

Title: Correlative operando microscopy of oxygen evolution electrocatalysts

Author: J. Tyler Mefford, Andrew R. Akbashev, Minkyung Kang, Cameron L. Bentley, William E. Gent, Haitao D. Deng, Daan Hein Alsem, Young-Sang Yu, Norman J. Salmon, David A. Shapiro, Patrick R. Unwin, William C. Chueh

Issue&Volume: 2021-05-05

Abstract: Transition metal (oxy)hydroxides are promising electrocatalysts for the oxygen evolution reaction1,2,3. The properties of these materials evolve dynamically and heterogeneously4 with applied voltage through ion insertion redox reactions, converting materials that are inactive under open circuit conditions into active electrocatalysts during operation5. The catalytic state is thus inherently far from equilibrium, which complicates its direct observation. Here, using a suite of correlative operando scanning probe and X-ray microscopy techniques, we establish a link between the oxygen evolution activity and the local operational chemical, physical and electronic nanoscale structure of single-crystalline β-Co(OH)2 platelet particles. At pre-catalytic voltages, the particles swell to form an α-CoO2H1.5·0.5H2O-like structure—produced through hydroxide intercalation—in which the oxidation state of cobalt is +2.5. Upon increasing the voltage to drive oxygen evolution, interlayer water and protons de-intercalate to form contracted β-CoOOH particles that contain Co3+ species. Although these transformations manifest heterogeneously through the bulk of the particles, the electrochemical current is primarily restricted to their edge facets. The observed Tafel behaviour is correlated with the local concentration of Co3+ at these reactive edge sites, demonstrating the link between bulk ion-insertion and surface catalytic activity.

DOI: 10.1038/s41586-021-03454-x

Source: https://www.nature.com/articles/s41586-021-03454-x

期刊信息

Nature:《自然》,创刊于1869年。隶属于施普林格·自然出版集团,最新IF:42.778
官方网址:http://www.nature.com/