The regulatory function of the d-orbital structure in TM@g-t-CN for bifunctional catalysis of the oxygen evolution/reduction reaction

• Published in: Physical chemistry chemical physics : PCCP 2023-12, Vol.26 (1), p.558-568
• Main Authors: Wang, Zhenduo, Wu, Meichen, Huang, Yuhong, Zhang, Jianmin, Wei, Xiumei
• Format: Article
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/d3cp04249a

Highly efficient catalysts for the oxygen evolution/reduction reaction (OER/ORR) have attracted great attention in research for energy devices with high conversion efficiency. Herein, systematic first-principles investigations are performed to explore the catalytic performance of graphitic C 4 N 3 loaded with single transition metal atoms (TM@g-t-C 4 N 3 ) for the OER/ORR. The results show that Fe, Co, Ni and Rh@g-t-C 4 N 3 exhibit fascinating bifunctional catalytic activities for both the OER and ORR. Moreover, it is observed that better activities are easily achieved when the valence d orbitals of doped TM atoms are nearly fully occupied. Further analysis reveals the volcano relationship between the OER/ORR performance and the adsorption Gibbs free energy. The adsorption free energy of intermediates in the OER/ORR process is also found to highly correlate with the electronic structures of TM@g-t-C 4 N 3 , which are mainly characterized by two quantities, one is the descriptor related to the electronegativity and the number of valence electrons in d orbitals, and the other is the projected d band center. The results indicate that it is possible to predict the catalytic performance of TM@g-t-C 4 N 3 by a detailed examination of the electronic properties of the doped TM atoms to some extent. This research not only provides several highly active g-t-C 4 N 3 -based single-atom catalysts (SACs) for the OER/ORR, but also reveals some potential regularities of SAC systems. A series of bifunctional OER/ORR SACs supported on g-t-C 4 N 3 is proposed. It is found from DFT calculations that the d-orbital structure can regulate the catalytic activity of g-t-C 4 N 3 -based SACs.