Janus-TiNbCO₂ for Hydrogen Evolution Reaction with High Conductivity and Catalytic Activity

Authors

Li-Li Xu, 1. Mianyang Vocational and Technical College, Department of Materials Enginerring, Mianyang 621000, Sichuan, China;Follow
Dong-Yan Ren, 1. Mianyang Vocational and Technical College, Department of Materials Enginerring, Mianyang 621000, Sichuan, China;
Xiao-Feng Zhao, 2. School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, Sichuan, China;3. Department of Physics and Astronomy, Uppsala University, 75120 Uppsala, Sweden;Follow
Yong Yi, 2. School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, Sichuan, China;

Corresponding Author

Li-Li Xu(ll-xu2008@163.com);
Xiao-Feng Zhao(xfz_33@126.com)

Abstract

Exploring the potential hydrogen evolution reaction (HER) catalysts with the high activity and high conductivity has always been a hot spot in the research of renewable energy development. Ti₂C, as one of the 2D-MXene, has excellent properties relating to many active sites, mechanical stability, conductivity, etc., and has become a potential HER catalyst. However, the modification of the surface of Ti₂C by terminal O will reduce the conductivity, thereby limiting the transport of electrons between the valence band and the conduction band. In this study, an electric double layer Janus-TiNbCO₂ was constructed by Nb doping. The band property, HER activity and HER reaction path of Janus-TiNbCO₂ are studied by the first-principles calculations. The results show that Nb doping increases the distance between Ti and O atoms, which increases the lattice parameters of Janus-TiNbCO₂ comparing with that of Ti₂CO₂ structure. The Janus-TiNbCO₂ structure is stable by calculating the thermodynamic stability at 500 K using AIMD method. The band gap of Ti₂CO₂ is approximate 0.9 eV. After Nb doping, the orbital hybridization between Nd-3d and O-2p affects the electronic rearrangement of Ti-3d, leading that Janus-TiNbCO₂ has the metal band structure. In Janus-TiNbCO₂, both Ti and Nb surfaces adsorb H* by O site, where the ΔG_H*(@Ti) = -0.55 eV,ΔG_H*(@Nb) = 0.02 eV, showing Ti and Nb surfaces have different catalytic activities. Comparing with graphenes, e.g., h-B₂O, Pt, and g-C₃N₄, Janus-TiNbCO₂ has better catalytic activity. The charge distribution of Janus-TiNbCO₂ near the Fermi level was analyzed by HSE-06 function. The result reveals that O atoms on the Ti surface exhibit charge unsaturation at the Fermi level, while those on Nb surface strong saturation. Moreover, the effects of H* coverage and strains(+2% ~ +4%) on the catalyst activity of Janus-TiNbCO₂ are studied. When the H* coverage is low, the optimal ΔG_H* of Nb surface is approximate 0.02 eV, while Ti surface has an excellent catalytic activity at high H* coverages (θ = 7/9, ΔG_H* = -0.06 eV). Under the strain action, the H* coverage on surface is not affected. However, strains will reduce the HER activity of Nb surface, and increase the HER activity of Ti surface. Furthermore, oxygen defect is a stable point defect in Janus-TiNbCO₂ . Oxygen defect will increase the HER activity of Ti surface and decrease the HER activity of Nb surface. Comparing to the Tafel pathway, the Heyrovsky is a more suitable pathway for the HER, in which the migration barrier of Heyrovsky is 0.23 eV for H* on Nb surface. Janus-TiNbCO₂ can be used as a potential HER catalyst.

Graphical Abstract

Keywords

MXene, Janus-TiNbCO2, band, hydrogen evolution reaction

DOI Link

https://doi.org/10.13208/j.electrochem.201109

Publication Date

2021-10-28

Online Available Date

2021-02-09

Revised Date

2020-12-22

Received Date

2020-11-09

Recommended Citation

Li-Li Xu, Dong-Yan Ren, Xiao-Feng Zhao, Yong Yi. Janus-TiNbCO₂ for Hydrogen Evolution Reaction with High Conductivity and Catalytic Activity[J]. Journal of Electrochemistry, 2021 , 27(5): 570-578.
DOI: 10.13208/j.electrochem.201109
Available at: https://jelectrochem.xmu.edu.cn/journal/vol27/iss5/5