School of Mechanical, Medical and Process Engineering, Queensland University of Technology, 2 George Street, Brisbane, QLD 4000, Australia.
Centre for Materials Science, Queensland University of Technology, 2 George Street, Brisbane, QLD 4000, Australia.
Mater Horiz. 2023 Feb 6;10(2):632-645. doi: 10.1039/d2mh01217k.
Iron (Fe) sites play a critical role in boosting the catalytic activity of transition metal layered double hydroxide (LDH) electrocatalysts for the oxygen evolution reaction (OER), but the contribution of the Fe content to the catalysis of Fe-doped LDHs is still not well understood. Herein, a series of two-dimensional (2D) Fe-doped MFe-LDHs (M = Co, Ni, Cu, and Mn) was synthesized a general molecular self-assembly method to track the role of Fe in their electrocatalytic OER activities. Besides the revelation of the intrinsic activity trend of NiFe > CoFe > MnFe > CuFe, volcano-shaped relationships among the catalytic activity descriptors, , overpotential, Tafel slope, and turnover frequency (TOF), and the Fe-content in MFe-LDHs, were identified. Specifically, a ∼20% Fe content resulted in the highest OER performance for the LDH, while excess Fe compromised its activity. A similar volcano relationship was determined between the intermediate adsorption and Fe content operando impedance spectroscopy (EIS) measurements, and it was shown that the intermediate adsorption capacitance (CPE) can be a new activity descriptor for electrocatalysts. In this work, we not only performed a systematic study on the role of Fe in 2D Fe-doped LDHs but also offer some new insights into the activity descriptors for electrocatalysts.
铁（Fe）位点在提高过渡金属层状双氢氧化物（LDH）电催化剂的氧析出反应（OER）催化活性方面起着关键作用，但 Fe 含量对掺杂 LDH 的催化作用仍未得到很好的理解。在此，采用通用的分子自组装方法合成了一系列二维（2D）Fe 掺杂的 MFe-LDHs（M=Co、Ni、Cu 和 Mn），以跟踪 Fe 在其电催化 OER 活性中的作用。除了揭示 NiFe>CoFe>MnFe>CuFe 的固有活性趋势外，还确定了催化活性描述符、过电势、塔菲尔斜率和周转频率（TOF）与 MFe-LDH 中 Fe 含量之间的火山形关系。具体而言，在 LDH 中，约 20%的 Fe 含量导致了最高的 OER 性能，而过量的 Fe 则会降低其活性。在中间吸附和 Fe 含量之间也确定了类似的火山关系，通过操作阻抗谱（EIS）测量进行了研究，表明中间吸附电容（CPE）可以成为电催化剂的新活性描述符。在这项工作中，我们不仅对 Fe 在 2D Fe 掺杂 LDH 中的作用进行了系统研究，还为电催化剂的活性描述符提供了一些新的见解。
