金属离子辅助转化法助力Ti_(3)C_(2)T_(x)前驱体衍生制备儿茶酚基MOF

Metal ion assistant transformation strategy to synthesize catechol-based metal-organic frameworks from Ti_(3)C_(2)T_(x)precursors

MXene具有丰富的高电负性末端原子、较大的比表面积和较小的原子厚度等优点,已被用作前驱体制备多种纳米材料.然而,目前已报道的用于衍生金属有机框架(MOF)的MXene仅限于V_(2)CT_(x).因此,通过增加MXene和有机配体的种类,合理设计和合成新型MOF,并进一步深入探索其合成机理仍是目前面临的重要挑战.本文采用金属离子辅助转化策略,以二维Ti_(3)C_(2)T_(x)为前驱体,合成了具有非互穿SrSi2(srs)框架的基于儿茶酚的三维(3D)TiCu-HHTP(HHTP=2,3,6,7,10,11-六羟基三苯)MOF.该策略表现出了良好的普适性,Ti3C2和辅助Cu^(2+)离子可以扩展到V2C MXene和其他辅助金属离子Mn^(+)(M=Ni^(2+)、Co^(2+),Mn^(2+)和Zn^(2+)).转化机制包括从Ti3C2纳米片到辅助金属离子的电荷转移、Ti-C键断裂促进释放Ti^(4+)离子以及Ti^(4+)/Mn^(+)与HHTP之间的强螯合配位协同促进TiCu-HHTP的形成.独特的3D导电网络和丰富的氧化还原位点赋予了TiCu-HHTP-7/PPy复合柔性透明电极快速的离子/电子传输和可逆的法拉第反应.在0.02 mA cm^(-2)电流密度下,TiCu-HHTP/PPy透明电极的面积比电容值达到3.63 mF cm^(-2),明显高于纯PPy电极的面积电容值(1.79 mF cm^(-2)).TiCu-HHTP/PPy透明电容器在0.75μW cm^(-2)的功率密度下,能量密度为0.042μWh cm^(-2).

Chemical transformation strategy is capable of fabricating nanomaterials with well-defined structures and fascinating performance via controllable crystallization kinetics in the phase transformation.V_(2)CT_(x) MXene has been used as precursors to fabricate vanadium porphyrin metal–organic frameworks(VPMOFs)via the coordination of deprotonated carboxylic acid ligands.However,the rational and indepth exploration of synthesis mechanism with the aim of enriching the variety of MXene(i.e.,Ti_(3)C_(2)T_(x))and organic ligands(i.e.,catechol-based)to design new MOFs is rarely reported.Herein,we have first developed a metal ion assistant transformation strategy to synthesize three-dimensional catecholbased TiCu-HHTP(HHTP=2,3,6,7,10,11-hexahydroxytriphenylene)MOFs with a non-interpenetrating SrSi2(srs)framework using two-dimensional Ti_(3)C_(2)T_(x)as precursors.The unique synergetic transformation mechanism involves the electron transfer from Ti_(3)C_(2)T_(x)to electrostatically adsorbed Cu^(2+)ion for redox reaction,the subsequent Ti–C bond rupture for Ti^(4+)ion release,and the continuous chelation coordination between Ti^(4+)/Cu^(2+)and HHTP.Ti_(3)C_(2)T_(x)precursors and auxiliary metal ion could be rationally substituted by V_(2)CT_(x) and Mn^(+)(e.g.,Ni^(2+),Co^(2+),Mn^(2+),and Zn^(2+)),respectively.This strategy lays the foundation for the design and synthesis of innovative and multifarious MOFs derived from MXene or other unconventional metal precursors.