一维g-C_(3)N_(4)/二维Ti_(3)C_(2)Tx界面调制促进光催化CO_(2)还原活性与选择性  

Regulating interfacial coupling of 1D crystalline g‐C_(3)N_(4) nanorods with 2D Ti_(3)C_(2)T_(x)MXene for boosting photocatalytic CO_(2) reduction

作　　者：钟蕤羽 梁玉洁 黄菲 梁诗诺 刘升卫 Ruiyu Zhong;Yujie Liang;Fei Huang;Shinuo Liang;Shengwei Liu(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)

机构地区：[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

出　　处：《Chinese Journal of Catalysis》2023年第10期109-122,共14页催化学报（英文）

基　　金：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).

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CO_(2)还原.反应(CO_(2)RR)为核心的人工光合成技术极具发展前景.石墨相氮化碳(g-C_(3)N_(4))作为一种二维层状光催化剂,化学性质稳定,且满足CO_(2)RR的热力学要求,但传统的g-C_(3)N_(4)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(Ti_(3)C_(2)Tx)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-C_(3)N_(4)光催化CO_(2)RR效率的有效手段.然而,g-C_(3)N_(4)光催化剂与Ti_(3)C_(2)Tx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-C_(3)N_(4)/Ti_(3)C_(2)Tx肖特基结光催化CO_(2)RR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-C_(3)N_(4)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 Ti_(3)C_(2)Tx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-C_(3)N_(4)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-C_(3)N_(4)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CO_(2)还原效率(2.13μmol^(-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 Ti_(3)C_(2)Tx助催化剂上富集的更高密度�Two-dimensional(2D)layered photocatalysts coupled with 2D Ti_(3)C_(2)T_(x)(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-C_(3)N_(4)(CCN)nanorods are grown along the c-axis using the molten-salt method and assembled onto a 2D Ti_(3)C_(2)T_(x)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 radialπ-conjugated plane to the hydrogen-bonded 2D Ti_(3)C_(2)T_(x)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-Ti_(3)C_(2)T_(x)hybrid photocatalyst assembled by freeze-drying(TC/CCN-FD)exhibited an outstanding photocatalytic CO_(2) reduction activity at a rate of 2.13μmol g^(–1)h^(–1),being 5.6 and 8.9 times more efficient than the pristine 1D CCN and 2D bulk g-C_(3)N_(4) counterparts,respectively.Moreover,the selectivity towards the multielectron reduction product(CH_(4))was significantly enhanced over TC/CCN-FD owing to the faster interfacial charge transfer across the CCN/Ti_(3)C_(2)T_(x)interface and the higher density of photoelectrons on the Ti_(3)C_(2)T_(x)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.

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 

分 类 号：O64[理学—物理化学]