Liu Kang, Fu Junwei, Lin Yiyang, Luo Tao, Ni Ganghai, Li Hongmei, Lin Zhang, Liu Min
Hunan Joint International Research Center for Carbon Dioxide Resource Utilization, School of Physics and Electronics, Central South University, Changsha, 410083, Hunan, P. R. China.
School of Metallurgy and Environment, Central South University, Changsha, 410083, Hunan, P. R. China.
Nat Commun. 2022 Apr 19;13(1):2075. doi: 10.1038/s41467-022-29797-1.
Single-atom Fe-N-C catalysts has attracted widespread attentions in the oxygen reduction reaction (ORR). However, the origin of ORR activity on Fe-N-C catalysts is still unclear, which hinder the further improvement of Fe-N-C catalysts. Herein, we provide a model to understand the ORR activity of Fe-N site from the spatial structure and energy level of the frontier orbitals by density functional theory calculations. Taking the regulation of divacancy defects on Fe-N site ORR activity as examples, we demonstrate that the hybridization between Fe 3dz, 3dyz (3dxz) and O π* orbitals is the origin of Fe-N ORR activity. We found that the Fe-O bond length, the d-band center gap of spin states, the magnetic moment of Fe site and *O as descriptors can accurately predict the ORR activity of Fe-N site. Furthermore, these descriptors and ORR activity of Fe-N site are mainly distributed in two regions with obvious difference, which greatly relate to the height of Fe 3d projected orbital in the Z direction. This work provides a new insight into the ORR activity of single-atom M-N-C catalysts.
单原子Fe-N-C催化剂在氧还原反应（ORR）中引起了广泛关注。然而，Fe-N-C催化剂上ORR活性的起源仍不清楚，这阻碍了Fe-N-C催化剂的进一步改进。在此，我们通过密度泛函理论计算提供了一个模型，从前沿轨道的空间结构和能级来理解Fe-N位点的ORR活性。以双空位缺陷对Fe-N位点ORR活性的调控为例，我们证明了Fe 3dz、3dyz（3dxz）与O π轨道之间的杂化是Fe-N ORR活性的起源。我们发现，Fe-O键长、自旋态的d带中心间隙、Fe位点和O的磁矩作为描述符可以准确预测Fe-N位点的ORR活性。此外，这些描述符和Fe-N位点的ORR活性主要分布在两个差异明显的区域，这与Fe 3d投影轨道在Z方向上的高度密切相关。这项工作为单原子M-N-C催化剂的ORR活性提供了新的见解。
