Citation: HAN Mengru, ZHOU Yanan, ZHOU Xuan, CHU Wei. Tunable Reactivity of MNi₁₂ (M = Fe, Co, Cu, Zn) Nanoparticles Supported on Graphitic Carbon Nitride in Methanation[J]. Acta Physico-Chimica Sinica, ;2019, 35(8): 850-857. doi: 10.3866/PKU.WHXB201811040 shu

Tunable Reactivity of MNi₁₂ (M = Fe, Co, Cu, Zn) Nanoparticles Supported on Graphitic Carbon Nitride in Methanation

HAN Mengru ¹ ,
ZHOU Yanan ¹ ,
ZHOU Xuan ¹ ,
CHU Wei ^1,2,,

1.
School of Chemical Engineering, Sichuan University, Chengdu 610065, P. R. China
2.
Institute of New Energy and Low-Carbon Technology, Sichuan University, Chengdu 610065, P. R. China

Corresponding author: CHU Wei, chuwei1965@scu.edu.cn
Received Date: 28 November 2018
Revised Date: 11 January 2018
Accepted Date: 11 January 2019
Available Online: 16 August 2019
Fund Project: This work is financially supported by the National Natural Science Foundation of China 21476145This work is financially supported by the National Natural Science Foundation of China (21476145)

As a unique two-dimensional material, graphitic carbon nitride (g-C₃N₄) has received significant attention for its particular electronic structure and chemical performance. Its instinctive defect can provide a stable anchoring site for metals, potentially improving the surface reactivity. Ni-based catalysts are economical but their activity for CO₂ methanation is lower than that of noble metal catalysts. Ni nanoparticles (NPs) supported on a substrate can further enhance the stability and activity of catalysts. Based on the principles of strong metal-support interaction (SMSI) and the synergistic effect on an alloy, MNi₁₂/g-C₃N₄ composites as novel catalysts are expected to improve stability and catalytic performance of Ni-based catalysts. The configurations are established with core-shell structures of MNi₁₂ (M = Fe, Co, Cu, Zn) nanoparticles (NPs) supported on g-C₃N₄ in this work. In the CO₂ methanation reaction, the reactivity of CO on slab (E_CO) is a critical factor, which is relative to the catalytic activity. Thus, the catalytic reactivity of these complexes via CO adsorption were explored using density functional theory (DFT). The values of cohesive energy (E_coh) for MNi₁₂ NPs range from -39.90 eV to -34.82 eV, suggesting that the formation of these NPs is favored as per thermodynamics, and E_coh and partial density of state (PDOS) reveal that the central M atom with the less filled d-shell interacts more strongly with surface Ni atoms. Therefore, ZnNi₁₂ is the most unstable structure among all the studied alloy, and the synergistic effect is also the weakest among them. When MNi₁₂ NPs are supported on the g-C₃N₄ substrate, the binding energies (E_b) vary from -9.40 eV to -8.39 eV, indicating that g-C₃N₄ is indeed a good material for stabilizing these NPs. The PDOS analysis of pure g-C₃N₄ suggests the sp² dangling bonds of N atoms in g-C₃N₄ can stabilize these transition metal NPs. Furthermore, the results of CO adsorbed on MNi₁₂ NPs and MNi₁₂/g-C₃N₄ composites show that E_CO and d_CO reduced with the introduction of g-C₃N₄. According to the results of the analysis of the Hirshfeld charges and electrostatic potential (ESP), the reason is that CO obtains less electrons from MNi₁₂ NPs after deposition on the g-C₃N₄ substrate, which lowers the reactivity of CO on catalysts. Additionally, the deformation charge density is analyzed to investigate the interaction between the NPs and g-C₃N₄. With the introduction of g-C₃N₄, charge redistribution indicates the strong metal-support interaction, which further reduces the CO adsorption energy. In summary, MNi₁₂ supported on g-C₃N₄ exhibit not only high stability but also tunable reactivity in CO₂ methanation. These changes are beneficial for CO₂ methanation reaction.
- SMSI,
- Core-shell structure,
- CO,
- Adsorption,
- Density functional theory
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Tunable Reactivity of MNi12 (M = Fe, Co, Cu, Zn) Nanoparticles Supported on Graphitic Carbon Nitride in Methanation

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通讯作者: 陈斌, bchen63@163.com

Tunable Reactivity of MNi₁₂ (M = Fe, Co, Cu, Zn) Nanoparticles Supported on Graphitic Carbon Nitride in Methanation