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

作　　者：邵翠萍 王文杰 程育汶 SHAO Cuiping;WANG Wenjie;CHENG Yuwen(School of Materials Science&Engineering,Anhui University of Technology,Maanshan 243002,China;Key Laboratory of Green Fabrication and Surface Technology of Advanced Metal Materials,Anhui University of Technology,Maanshan 243002,China)

机构地区：[1]安徽工业大学材料科学与工程学院,安徽马鞍山243002 [2]安徽工业大学先进金属材料绿色制造与表面技术教育部重点实验室,安徽马鞍山243002

出　　处：《安徽工业大学学报（自然科学版）》2024年第3期265-275,共11页Journal of Anhui University of Technology（Natural Science）

基　　金：国家自然科学基金项目(51971002);安徽省自然科学基金项目(2108085QE188);安徽省高校自然科学基金项目(KJ2021A0361)。

摘　　要：基于第一性原理,计算二维过渡金属碳氮化物(MXenes)Ti_(2)CT_(2)和Ti_(3)C_(2)T_(2)(T=O^(*)或OH^(*))催化剂表面N_(2)吸附前后的态密度(DOS)、反应中间结构的吉布斯自由能(△G)、差分电荷(CDD)、功函数φ及活化能(E_(a)),探究OH^(*)终端MXene表面发生N_(2)还原反应(NRR)反应的机制。结果发现:N_(2)在Ti_(2)CO_(2)和Ti_(3)C_(2)O_(2)表面发生物理吸附(△q≈0e),在Ti_(2)C(OH)_(2)和Ti_(3)C_(2)(OH)_(2)表面发生化学吸附(△q>0.2e),Ti_(2)CO_(2)(η_(NRR)=2.13 V)和Ti_(3)C_(2)O_(2)(η_(NRR)=2.03 V)催化剂由于过高的加氢过电位(η_(NRR))而不利于发生NRR;Ti_(2)C(OH)_(2)和Ti_(3)C_(2)(OH)_(2)表面可在起始步骤N_(2)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,η_(NRR)与功函数φ存在ηNRR=0.44φ−0.71函数关系,线性相关系数(R^(2))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,N_(2)在Ti_(2)C(OH)_(2)和Ti_(3)C_(2)(OH)_(2)表面的N_(2)通过“N_(2)+2^(*)H=^(*)N_(2)H_(2)”进行吸附,然后沿Enzymatic机制进行NRR。The density of states(DOS),Gibbs free energy(△G)of the reaction intermediate structure,charge density difference(CDD),work function and activation energies(E_(a))of the reaction intermediate structure on the surface of two-dimensional transition metal carbon nitride(MXenes)Ti_(2)CT_(2)and Ti_(3)C_(2)T_(2)(T=O^(*)or OH^(*))catalysts before and after N_(2)adsorption were calculated by first-principles,to explore the new mechanism of N_(2)reduction reaction(NRR)on the surface of OH^(*)terminal MXene.The results show that N_(2)undergoes physical adsorption on Ti_(2)CO_(2)and Ti_(3)C_(2)O_(2)surfaces(△q≈0e),while chemical adsorption occurs on Ti_(2)C(OH)_(2)and Ti_(3)C_(2)(OH)_(2)surfaces(△q>0.2e),Ti_(2)CO_(2)and Ti_(3)C_(2)O_(2)are not conducive to NRR due to high η_(NRR).While Ti_(2)C(OH)_(2)and Ti_(3)C_(2)(OH)_(2)surfaces can provide H atoms during the initial adsorption step and undergo NRR through the Enzymatic mechanism,with the corresponding η_(NRR) decreasing to 0.29 V and 0.38 V,respectively.Moreover,the calculatedηNRR can be used as a function ofφ:η_(NRR)=0.44φ−0.71,where the correlation coefficient(R^(2))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 N_(2)is adsorbed on Ti_(2)C(OH)_(2)and Ti_(3)C_(2)(OH)_(2)via“N_(2)+2^(*)H=^(*)N_(2)H_(2)”,followed by NRR along the Enzymatic mechanism.

关 键 词：二维过渡金属碳氮化物 氮气还原 加氢 第一性原理 

分 类 号：TB33[一般工业技术—材料科学与工程]