Zhang Zhe, Zhang Fan, Cui Yu, Luo Wen, Shu Miao, Wang Shuren, Lu Zhouguang, Hou Yanglong, Hao Rui
Department of Chemistry, Southern University of Science and Technology, 518055 Shenzhen, China.
Songshan Lake Materials Laboratory, 523808 Dongguan, China.
J Am Chem Soc. 2025 Jul 9;147(27):23617-23624. doi: 10.1021/jacs.5c04465. Epub 2025 Jun 27.
The (0001) crystal facet of β-Co(OH) has been widely accepted as an inert facet for the oxygen evolution reaction (OER), while the (101̅0) facet is considered more active. However, mechanistic details regarding the origin of the differences at the coordination environment and the electronic state level remain unexplored to date. Herein, we used a multimode optical imaging method to track the evolving heterogeneous dynamics of cobalt species during the OER process and correlate it with the OER performance. Cobalt underwent the oxidation to Co, distorted to Co, and subsequently oxidized to Co, in which the distribution was mapped by vis-absorption imaging. It indicates that cobalt was negligibly oxidized to Co on the (0001) facet, because of the coordination-saturated environment, while it was relatively facile on the (101̅0) facet. The adsorbate evolution mechanism (AEM) process and lattice-oxygen-mediated mechanism (LOM) process during OER were spatiotemporally decoupled by electrochemiluminescence (ECL) imaging. Furthermore, the cobalt oxidation kinetics was tailored by the atom topping (Fe/Ni) strategy, which was accelerated by iron doping and retarded by nickel doping. On this basis, we propose a lattice O-involved mechanism for transforming Co to Co, which is a crucial step to Co. The accelerated oxidation kinetics is from the enrichment of O, which induces abundant coordination-unsaturated cobalt, facilitating the transformation to Co. This study examined the oxidation kinetics of cobalt with high spatiotemporal resolution and further tailors the distribution of Co, which is expected to promote future research on the kinetic tuning of crystal facets.
β-Co(OH) 的 (0001) 晶面已被广泛认为是析氧反应 (OER) 的惰性晶面，而 (101̅0) 晶面则被认为更具活性。然而，迄今为止，关于配位环境和电子态水平差异起源的机理细节仍未得到探索。在此，我们使用多模光学成像方法来跟踪OER过程中钴物种不断演变的异质动力学，并将其与OER性能相关联。钴经历了氧化为Co，扭曲为Co，随后氧化为Co的过程，其分布通过可见吸收成像进行映射。这表明由于配位饱和环境，钴在 (0001) 晶面上氧化为Co的程度可忽略不计，而在 (101̅0) 晶面上则相对容易。通过电化学发光 (ECL) 成像在时空上解耦了OER过程中的吸附质演化机制 (AEM) 过程和晶格氧介导机制 (LOM) 过程。此外，通过原子封顶 (Fe/Ni) 策略调整了钴的氧化动力学，铁掺杂加速了氧化，镍掺杂则减缓了氧化。在此基础上，我们提出了一种涉及晶格O将Co转化为Co的机制，这是转化为Co的关键步骤。加速的氧化动力学源于O的富集，这诱导了大量配位不饱和的钴，促进了向Co的转化。本研究以高时空分辨率研究了钴的氧化动力学，并进一步调整了Co的分布，有望推动未来关于晶面动力学调控的研究。
