催化学报 ›› 2023, Vol. 53: 109-122.DOI: 10.1016/S1872-2067(23)64513-9

• 论文 • 上一篇    下一篇

一维g-C3N4/二维Ti3C2Tx界面调制促进光催化CO2还原活性与选择性

钟蕤羽,1, 梁玉洁,1, 黄菲, 梁诗诺, 刘升卫()   

  1. 中山大学环境科学与工程学院, 广东省环境污染控制与修复技术重点实验室, 广东广州510006
  • 收稿日期:2023-06-26 接受日期:2023-07-27 出版日期:2023-10-18 发布日期:2023-10-25
  • 通讯作者: *电子信箱: liushw6@mail.sysu.edu.cn (刘升卫).
  • 作者简介:

    1共同第一作者.

  • 基金资助:
    国家自然科学基金(51872341);广东省“特支计划”科技创新青年拔尖人才项目(2019TQ05L196)

Regulating interfacial coupling of 1D crystalline g-C3N4 nanorods with 2D Ti3C2Tx MXene for boosting photocatalytic CO2 reduction

Ruiyu Zhong,1, Yujie Liang,1, Fei Huang, Shinuo Liang, Shengwei Liu()   

  1. School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou 510006, Guangdong, China
  • Received:2023-06-26 Accepted:2023-07-27 Online:2023-10-18 Published:2023-10-25
  • Contact: *liushw6@mail.sysu.edu.cn (S. Liu).
  • About author:

    1Contributed equally to this work.

  • Supported by:
    The National Natural Science Foundation of China(51872341);The Tip-top Scientific and Technical Innovative Youth Talents of Guangdong Special Support Program(2019TQ05L196)

摘要:

碳中和是实现绿色可持续发展重要途径之一, 以半导体光催化CO2还原反应(CO2RR)为核心的人工光合成技术极具发展前景. 石墨相氮化碳(g-C3N4)作为一种二维层状光催化剂, 化学性质稳定, 且满足CO2RR的热力学要求, 但传统的g-C3N4光催化活性和选择性较低, 这主要归因于高的电荷复合几率和低的光电子利用效率. 采用二维碳化钛(Ti3C2Tx)等碳基助催化剂作为电子受体, 促进光生载流子的快速分离与转移, 成为提高g-C3N4光催化CO2RR效率的有效手段. 然而, g-C3N4光催化剂与Ti3C2Tx助催化剂多数以2D/2D构型界面耦合, 受限于二者界面弱的范德华相互作用、高的界面静电势垒和缓慢的界面电荷转移速率, 2D/2D g-C3N4/Ti3C2Tx肖特基结光催化CO2RR活性与选择性仍普遍欠佳.

针对该问题, 本文采用熔盐法制备了沿c轴方向生长的1D高结晶g-C3N4纳米棒(CCN), 并通过冷冻干燥辅助界面耦合的方法将其组装到2D Ti3C2Tx基底上, 在冷冻干燥条件下, CCN边缘的NHx与MXene表面-O/-OH基团会形成更强的界面氢键耦合作用, 最终构筑具有独特界面氢键作用的1D/2D肖特基结光催化剂(记作1D/2D TC/CCN-FD). 扫描电镜和透射电镜结果证明了复合材料的成功制备. X射线光电子能谱和密度泛函理论(DFT)计算结果证明了界面电荷的定向转移. 瞬态光电流、Nyquist曲线、荧光光谱和DFT计算结果表明, 由于g-C3N4纳米棒光催化剂沿π共轭平面的电荷传输势垒远低于以范德华相互连接的g-C3N4层间的电荷传输势垒, 1D/2D构型界面耦合可以降低界面电荷转移能垒, 加快界面电荷转移速率. 气相色谱结果表明, 优化组成结构得到的1D/2D TC/CCN-FD复合光催化剂表现出较好的光催化CO2还原效率(2.13 μmol g-1 h-1), 分别是1D CCN和2D传统氮化碳的5.6和8.9倍. 同时, 2D Ti3C2Tx助催化剂上富集的更高密度的光电子, 促使多电子还原产物(CH4)的选择性显著提高到60%以上(产率为1.4 μmol g-1 h-1). 原位漫反射红外傅里叶变换光谱和同位素标定结果进一步明确了CO2RR反应路径和反应机理.

综上所述, 本文揭示了界面晶体取向匹配与界面强耦合作用对促进高效界面光电子定向迁移具有重要协同作用, 为未来开发高性能异质结光催化剂提供新思路.

关键词: 碳化钛, 高结晶氮化碳, 一维/二维, 光催化二氧化碳还原, 助催化剂

Abstract:

Two-dimensional (2D) layered photocatalysts coupled with 2D Ti3C2Tx (T = OH, O, or F) MXene cocatalysts in 2D/2D configuration have been extensively studied for use in artificial photosynthesis. Unfortunately, the overall photoreaction efficiency of these cocatalysts is often limited by weak 2D/2D interfacial van der Waals interactions, high interfacial electrostatic barriers, and slow interfacial charge transfer. In this study, 1D crystalline g-C3N4 (CCN) nanorods are grown along the c-axis using the molten-salt method and assembled onto a 2D Ti3C2Tx substrate by freeze-drying-assisted interfacial coupling, forming a unique Schottky junction photocatalyst in a 1D/2D configuration with interfacial hydrogen bonds. Transfer of photoelectrons in the CCN nanorods could along the radial π-conjugated plane to the hydrogen-bonded 2D Ti3C2Tx in the 1D/2D configuration is more efficient than the slow interlayer charge transfer in catalysts with a conventional 2D/2D configuration. Consequently, the optimized 1D-CCN/2D-Ti3C2Tx hybrid photocatalyst assembled by freeze-drying (TC/CCN-FD) exhibited an outstanding photocatalytic CO2 reduction activity at a rate of 2.13 μmol g-1 h-1, being 5.6 and 8.9 times more efficient than the pristine 1D CCN and 2D bulk g-C3N4 counterparts, respectively. Moreover, the selectivity towards the multielectron reduction product (CH4) was significantly enhanced over TC/CCN-FD owing to the faster interfacial charge transfer across the CCN/Ti3C2Tx interface and the higher density of photoelectrons on the Ti3C2Tx cocatalysts. This work will inspire further studies on suppressing the interfacial charge transfer barrier by matching the interfacial crystal orientation and strengthening the interfacial interactions.

Key words: Ti3C2Tx, Crystalline carbon nitride, 1 dimension/2 dimension, Photocatalytic CO2 reduction, Cocatalyst