Kavalsky Lance, Viswanathan Venkatasubramanian
Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States.
Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States.
J Phys Chem C Nanomater Interfaces. 2024 Aug 22;128(35):14611-14620. doi: 10.1021/acs.jpcc.4c01867. eCollection 2024 Sep 5.
A promising route toward room-temperature ironmaking is electrowinning, where iron ore dissolution is coupled with cation electrodeposition to grow pure iron. However, poor faradaic efficiencies against the hydrogen evolution reaction (HER) is a major bottleneck. To develop a mechanistic picture of this technology, we conduct a first-principles thermodynamic analysis of the Fe110 aqueous electrochemical interface. Constructing a surface Pourbaix diagram, we predict that the iron surface will always drive toward adsorbate coverage. We calculate theoretical overpotentials for terrace and step sites and predict that growth at the step sites are likely to dominate. Investigating the hydrogen surface phases, we model several hydrogen absorption mechanisms, all of which are predicted to be endothermic. Additionally, for HER we identify step sites as being more reactive than on the terrace and with competitive limiting potentials to iron plating. The results presented here further motivate electrolyte design toward HER suppression.
一种有前景的室温炼铁途径是电解沉积，即将铁矿石溶解与阳离子电沉积相结合以生长纯铁。然而，析氢反应（HER）的法拉第效率低下是一个主要瓶颈。为了建立该技术的机理模型，我们对Fe110水相电化学界面进行了第一性原理热力学分析。通过构建表面Pourbaix图，我们预测铁表面将始终趋向于吸附质覆盖。我们计算了平台和台阶位点的理论过电位，并预测台阶位点的生长可能占主导。通过研究氢表面相，我们对几种氢吸收机制进行了建模，所有这些机制预计都是吸热的。此外，对于HER，我们确定台阶位点比平台更具反应性，并且对铁电镀具有竞争性极限电位。此处给出的结果进一步推动了抑制HER的电解质设计。
