2D MXene(Ti_(3)CNT_(x))has been considered as the most promising electrode material for flexible supercapacitors owing to its metallic conductivity,ultra-high capacitance,and excellent flexibility.However,it suffers f...2D MXene(Ti_(3)CNT_(x))has been considered as the most promising electrode material for flexible supercapacitors owing to its metallic conductivity,ultra-high capacitance,and excellent flexibility.However,it suffers from a severe restacking problem during the electrode fabrication process,limiting the ion transport kinetics and the accessibility of ions in the electrodes,especially in the direction normal to the electrode surface.Herein,we report a NH_(3)-induced in situ etching strategy to fabricate 3D-interconnected porous MXene/carbon dots(p-MC)films for high-performance flexible supercapacitor.The pre-intercalated carbon dots(CDs)first prevent the restacking of MXene to expose more inner electrochemical active sites.The partially decomposed CDs generate NH_(3)for in situ etching of MXene nanosheets toward 3D-interconnected p-MC films.Benefiting from the structural merits and the 3D-interconnected ionic transmission channels,p-MC film electrodes achieve excellent gravimetric capacitance(688.9 F g^(-1)at 2 A g^(-1))and superior rate capability.Moreover,the optimized p-MC electrode is assembled into an asymmetric solid-state flexible supercapacitor with high energy density and superior cycling stability,demonstrating the great promise of p-MC electrode for practical applications.展开更多
Ti3CNTx MXenes with unique electrical conductivity can be widely applied for supercapacitors and electromagnetic shielding.However,its relatively low-yield quaternary nitrogen-containing Ti3AlCN ce ramics precursor(le...Ti3CNTx MXenes with unique electrical conductivity can be widely applied for supercapacitors and electromagnetic shielding.However,its relatively low-yield quaternary nitrogen-containing Ti3AlCN ce ramics precursor(less than 50%),due to the inevitable Al segregation during the synthesizing process,significantly hindered its widely commercial applications.Herein,we employed the controllable AlNoversaturation precursor strategy to precisely tune the phase transition point of quaternary Ti3AlCN ceramics to obtain high-yield Ti3 AlCN precursor for the purpose of high conductivity Ti3 CNTx MXenes.Combined energy dispersive X-ray spectrometer(XRD)with X-ray photoelectron spectroscopy(XPS)characterizations,the yield of the quaternary nitrogen-containing Ti3 AlCN ceramics was evidently proved to be up to 70%,which is 1.4 times than that of previously reported works.Such relatively highyield quaternary Ti3AlCN is mainly ascribed to the elimination of Al segregation.Based on it,we further developed accordion-like two-dimensional(2D)MXene via hydrofluoric acid etch and vacuum freezedry.This novel accordion-like 2D Ti3CNTx MXene possesses high electrochemical capacitive properties(209 F/g).Therefore,this controllable AlN-oversaturation precursor strategy will pave a way to exploit costly high-yield MAX ceramics precursor for high conductivity MXenes and also play a powerful role in promoting their practical applications including electrical and magnetic engineering fields.展开更多
基金The authors gratefully acknowledge financial support from the National Natural Science Foundation of China(Grant Nos.21805261 and 51972277)Sichuan Science and Technology Program(Grant Nos.2021YFG0251 and 2022YFG0293)Fundamental Research Funds for the Central Universities(Grant No.2682021CX105)。
文摘2D MXene(Ti_(3)CNT_(x))has been considered as the most promising electrode material for flexible supercapacitors owing to its metallic conductivity,ultra-high capacitance,and excellent flexibility.However,it suffers from a severe restacking problem during the electrode fabrication process,limiting the ion transport kinetics and the accessibility of ions in the electrodes,especially in the direction normal to the electrode surface.Herein,we report a NH_(3)-induced in situ etching strategy to fabricate 3D-interconnected porous MXene/carbon dots(p-MC)films for high-performance flexible supercapacitor.The pre-intercalated carbon dots(CDs)first prevent the restacking of MXene to expose more inner electrochemical active sites.The partially decomposed CDs generate NH_(3)for in situ etching of MXene nanosheets toward 3D-interconnected p-MC films.Benefiting from the structural merits and the 3D-interconnected ionic transmission channels,p-MC film electrodes achieve excellent gravimetric capacitance(688.9 F g^(-1)at 2 A g^(-1))and superior rate capability.Moreover,the optimized p-MC electrode is assembled into an asymmetric solid-state flexible supercapacitor with high energy density and superior cycling stability,demonstrating the great promise of p-MC electrode for practical applications.
基金supported by the National Natural Science Foundation of China(No.51602265)the Special Fund of China Postdoctoral Science Foundation(No.2018T110992)+1 种基金the Sichuan Science and Technology Program(No.2018RZ0074)the Cultivation Program for the Excellent Doctoral Dissertation of Southwest Jiaotong University(No.D-YB201709)。
文摘Ti3CNTx MXenes with unique electrical conductivity can be widely applied for supercapacitors and electromagnetic shielding.However,its relatively low-yield quaternary nitrogen-containing Ti3AlCN ce ramics precursor(less than 50%),due to the inevitable Al segregation during the synthesizing process,significantly hindered its widely commercial applications.Herein,we employed the controllable AlNoversaturation precursor strategy to precisely tune the phase transition point of quaternary Ti3AlCN ceramics to obtain high-yield Ti3 AlCN precursor for the purpose of high conductivity Ti3 CNTx MXenes.Combined energy dispersive X-ray spectrometer(XRD)with X-ray photoelectron spectroscopy(XPS)characterizations,the yield of the quaternary nitrogen-containing Ti3 AlCN ceramics was evidently proved to be up to 70%,which is 1.4 times than that of previously reported works.Such relatively highyield quaternary Ti3AlCN is mainly ascribed to the elimination of Al segregation.Based on it,we further developed accordion-like two-dimensional(2D)MXene via hydrofluoric acid etch and vacuum freezedry.This novel accordion-like 2D Ti3CNTx MXene possesses high electrochemical capacitive properties(209 F/g).Therefore,this controllable AlN-oversaturation precursor strategy will pave a way to exploit costly high-yield MAX ceramics precursor for high conductivity MXenes and also play a powerful role in promoting their practical applications including electrical and magnetic engineering fields.
