Xu Hao, Wang Dan, Yang Peixia, Liu Anmin, Li Ruopeng, Li Yun, Xiao Lihui, Zhang Jinqiu, An Maozhong
MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, 150001, China.
Phys Chem Chem Phys. 2020 Dec 23;22(48):28297-28303. doi: 10.1039/d0cp04676k.
Carbon-based, non-noble metal catalysts for the oxygen reduction reaction (ORR) are crucial for the large-scale application of metal-air batteries and fuel cells. Density functional theory calculations were performed to explore the potential of atomically dispersed MN4/C (M = Fe or Mn) as an ORR catalyst in an acidic electrolyte and the ORR mechanism on MN4/C was systematically studied. The results indicated MN4 as the active site of MN4/C and a four-electron OOH transformation pathway as the preferred ORR mechanism on the MN4/C surface. The Gibbs free energy diagram showed that the rate-determining step of the FeN4/C and MnN4/C catalysts is the formation of the second H2O molecule and OOH*, respectively. FeN4/C exhibited higher thermodynamic limiting potential (0.79 V) and, thus, higher ORR activity than MnN4/C (0.52 V) in an acidic environment; its excellent catalytic performance is due to the nice electron structure and adsorption properties of the FeN4 site. Therefore, this work demonstrates that atomically dispersed MN4/C is a promising catalyst for the ORR.
用于氧还原反应（ORR）的碳基非贵金属催化剂对于金属空气电池和燃料电池的大规模应用至关重要。进行了密度泛函理论计算，以探索原子分散的MN4/C（M = Fe或Mn）作为酸性电解质中ORR催化剂的潜力，并系统地研究了MN4/C上的ORR机理。结果表明，MN4是MN4/C的活性位点，四电子OOH转化途径是MN4/C表面上首选的ORR机理。吉布斯自由能图表明，FeN4/C和MnN4/C催化剂的速率决定步骤分别是第二个H2O分子和OOH*的形成。在酸性环境中，FeN4/C表现出更高的热力学极限电位（0.79 V），因此比MnN4/C（0.52 V）具有更高的ORR活性；其优异的催化性能归因于FeN4位点良好的电子结构和吸附性能。因此，这项工作表明原子分散的MN4/C是一种很有前途的ORR催化剂。
