Reducing dielectric confinement effect in ionic covalent organic nanosheets to promote the visible-light-driven hydrogen evolution  

作　　者：Guoqing Li Xiaolong Zhao Qihong Yue Ping Fu Fangpei Ma Jun Wang Yu Zhou 

机构地区：[1]State Key Laboratory of Materials-Oriented Chemical Engineering,College of Chemical Engineering,Nanjing Tech University,Nanjing 211816,Jiangsu,China

出　　处：《Journal of Energy Chemistry》2023年第7期40-46,I0002,共8页能源化学（英文版）

基　　金：the National Natural Science Foundation of China(22072065,22178162,22222806);the Distinguished Youth Foundation of Jiangsu Province(BK20220053);the Six Talent Peaks Project in Jiangsu Province(JNHB-035)。

摘　　要：Ultra-thin two-dimensional(2D)organic semiconductors are promising candidates for photocatalysts because of the short charge diffusion pathway and favorable exposure of active sites plus the versatile architecture.Nonetheless,the inherent dielectric confinement of 2D materials will induce a strong exciton effect hampering the charge separation.Herein,we demonstrated an effective way to reduce the dielectric confinement effect of 2D ionic covalent organic nanosheets(iCONs)by tailoring the functional group via molecular engineering.Three ultra-thin CONs with different functional groups and the same ionic moieties were synthesized through Schiff base condensation between ionic amino monomer triaminoguanidinium chloride(TG)and aldehyde linkers.The integration of the hydroxyl group was found to significantly increase the dielectric constant by enhancing the polarizability of ionic moieties,and thus reduced the dielectric confinement and the corresponding exciton binding energy(E_(b)).The champion hydroxyl-functional iCON exhibited promoted exciton dissociation and in turn a high photocatalytic hydrogen production rate under visible-light irradiation.This work provided insights into the rationalization of the dielectric confinement effect of low-dimensional photocatalysts.

关 键 词：PHOTOCATALYSIS H_(2)evolution Ionic covalent organic framework NANOSHEETS 2D material Polarization 

分 类 号：O643.36[理学—物理化学] O644.1[理学—化学] TB383.1[一般工业技术—材料科学与工程]