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邵翠萍,王文杰,程育汶. Ti基MXenes表面氮气还原机理的第一性原理研究[J]. 安徽工业大学学报(自然科学版),2024,41(3):265-275. doi: 10.12415/j.issn.1671-7872.23160
引用本文: 邵翠萍,王文杰,程育汶. Ti基MXenes表面氮气还原机理的第一性原理研究[J]. 安徽工业大学学报(自然科学版),2024,41(3):265-275. doi: 10.12415/j.issn.1671-7872.23160
SHAO Cuiping, WANG Wenjie, CHENG Yuwen. A Study of First Principles on Nitrogen Reduction Mechanism at the Surface of Ti Based Two-dimensional Transition Metal Carbides[J]. Journal of Anhui University of Technology(Natural Science), 2024, 41(3): 265-275. DOI: 10.12415/j.issn.1671-7872.23160
Citation: SHAO Cuiping, WANG Wenjie, CHENG Yuwen. A Study of First Principles on Nitrogen Reduction Mechanism at the Surface of Ti Based Two-dimensional Transition Metal Carbides[J]. Journal of Anhui University of Technology(Natural Science), 2024, 41(3): 265-275. DOI: 10.12415/j.issn.1671-7872.23160

Ti基MXenes表面氮气还原机理的第一性原理研究

A Study of First Principles on Nitrogen Reduction Mechanism at the Surface of Ti Based Two-dimensional Transition Metal Carbides

  • 摘要: 基于第一性原理,计算二维过渡金属碳氮化物(MXenes)Ti2CT2和Ti3C2T2 (T=O*或OH*)催化剂表面N2吸附前后的态密度(DOS)、反应中间结构的吉布斯自由能(ΔG)、差分电荷(CDD)、功函数φ及活化能(Ea),探究OH*终端MXene表面发生N2还原反应(NRR)反应的机制。结果发现:N2在Ti2CO2和Ti3C2O2表面发生物理吸附(∆q≈0e),在Ti2C(OH)2和Ti3C2(OH)2表面发生化学吸附(∆q>0.2e),Ti2CO2 (ηNRR=2.13 V)和Ti3C2O2 (ηNRR=2.03 V)催化剂由于过高的加氢过电位(ηNRR)而不利于发生NRR;Ti2C(OH)2和Ti3C2(OH)2表面可在起始步骤N2吸附时提供H原子,并通过Enzymatic机制发生NRR,相应的ηNRR分别降至0.29,0.38 V;此外,ηNRR与功函数φ存在ηNRR=0.44φ−0.71函数关系,线性相关系数(R2)为0.97,两者存在较大的线性相关性;在*OH终端与*O终端表面N 2p轨道和O 2p轨道能级杂化强度不同,导致OH* MXene的NRR活性不同。由此认为,N2在Ti2C(OH)2和Ti3C2(OH)2表面的N2通过“N2+2*H=*N2H2”进行吸附,然后沿Enzymatic机制进行NRR。

     

    Abstract: The density of states (DOS) , Gibbs free energy (ΔG)of the reaction intermediate structure, charge density difference (CDD), work function and activation energies (Ea) of the reaction intermediate structure on the surface of two-dimensional transition metal carbon nitride (MXenes) Ti2CT2 and Ti3C2T2 (T=O* or OH*) catalysts before and after N2 adsorption were calculated by first-principles, to explore the new mechanism of N2 reduction reaction (NRR) on the surface of OH* terminal MXene. The results show that N2 undergoes physical adsorption on Ti2CO2 and Ti3C2O2 surfaces (∆q≈0e), while chemical adsorption occurs on Ti2C(OH)2 and Ti3C2(OH)2 surfaces (∆q>0.2e), Ti2CO2 and Ti3C2O2 are not conducive to NRR due to high ηNRR. While Ti2C(OH)2 and Ti3C2(OH)2 surfaces can provide H atoms during the initial adsorption step and undergo NRR through the Enzymatic mechanism, with the corresponding ηNRR decreasing to 0.29 V and 0.38 V, respectively. Moreover, the calculated ηNRR can be used as a function of φ: ηNRR=0.44φ−0.71, where the correlation coefficient (R2) is 0.97, showing a strong linear relationship between overpotential and work function. The hybridization intensity of N 2p and O 2p orbitals on the surface of *OH terminal and *O terminal is different, resulting in different NRR activity of OH* MXene. Therefore, it is believed that N2 is adsorbed on Ti2C(OH)2 and Ti3C2(OH)2 via “N2+2*H=*N2H2” , followed by NRR along the Enzymatic mechanism.

     

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