School of Chemistry, Xi'an Key Laboratory of Sustainable Energy Materials Chemistry, State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Xi'an, 710049, China.
Laboratory of Inorganic Materials and Catalysis, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands.
Chemphyschem. 2022 Aug 3;23(15):e202200165. doi: 10.1002/cphc.202200165. Epub 2022 Jun 7.
Iron-nitrogen-carbon materials have been known as the most promising non-noble metal catalyst for proton-exchange membrane fuel cells (PEMFCs), but the genuine active sites for oxygen reduction reaction (ORR) are still arguable. Herein, by the thorough density functional theory investigations, we unravel that the planar Fe N site exhibits excellent ORR catalytic activity over both FeN and FeN sites, and the potential-determining step is determined to be the *OH hydrogenation step with an overpotential of 0.415 V. The ORR activity of Fe N site originates from the low spin magnetic moment (1.11 μ ), which leads to high antibonding states and low d-band center of the Fe center, further leads to weak binding strength of *OH species. The density of FeN sites only has little influence on the ORR activity owing to the similar interaction between active site and intermediates in ORR. Our research sheds light on the activity origin of iron-nitrogen-carbon materials for ORR.
铁氮碳材料一直被认为是质子交换膜燃料电池（PEMFCs）中最有前途的非贵金属催化剂，但对于氧还原反应（ORR）的真正活性位点仍存在争议。在此，通过深入的密度泛函理论研究，我们揭示了平面 FeN 位在 FeN 和 FeN 位上均表现出优异的 ORR 催化活性，并且决速步骤被确定为具有 0.415 V 过电势的OH 加氢步骤。FeN 位的 ORR 活性源于低自旋磁矩（1.11 μ），导致 Fe 中心的反键态高和 d 带中心低，从而导致OH 物种的结合强度较弱。FeN 位的密度对 ORR 活性的影响很小，这是由于活性位点与 ORR 中间物之间的相互作用相似。我们的研究揭示了铁氮碳材料用于 ORR 的活性起源。
