Synthesis And Electrochemical Properties Of Polyaniline Composites Supported By Polyhydroxylated Ti₃C₂T_x

MXenes are a novel class of two-dimensional transition metal carbide/nitride family with excellent energy storage,which are regarded as promising electrode materials for high-performance supercapacitors.Ti₃C₂T_x is the most studied MXenes with extensive applications.However,the addition of OH^-and F^-groups belong to competiting substitution reaction during the etching process,Ti₃C₂T_x has a large number of-F functional groups with low chemical activity.In addition,the obtained flakes trend to easily stackable and borken,resulting in low chemical activity and electrochemical performance,along with the oxidization of Ti₃C₂T_x flackes to TiO₂ in oxidable medium.In this context,we modifie the surface functional groups of Ti₃C₂T_x to reduce the low chemical activity functional groups content.The purpose is to reduce the self-stacking of Ti₃C₂T_x sheets and increase the chemical activity and electrochemical performance.Futhermore,the hybrid composites composed of Ti₃C₂T_x and polyaniline?PANI?hybrid materials were synthesized through electrostatic adsorption processes,aiming to improve the electrochemical performance with complementary synergistic effects.This article mainly includes the following aspects:?1?For the above-mentioned reasons,the content of-O and-OH was effectively increased based on the dominance of-OH on the surface termination structure under alkali treatment followed by the formation of two-dimensional structure with aid of acid treatment.As a result,the proportion of-OH and-O suface active terminated groups increase from 47.28%to 74.61%.Furthermore,the increase of hydrophilic functional groups have better dispersion properties,larger interlayer spacing and lower self-stacking.The specific surface area was increased from 4.388 m²/g to 7.375 m²/g,which improved the electric double layer capacitance content of the material.Cyclic voltammetry tests showed that the Ti₃C₂T_x exhibited specific capacitance of 103 F/g at a scan rate of 10mV/s and 90 F/g at a scan rate of 50 mV/s with capacitance retention more than 87%.Moreover,up to 94%capacitance retention is achieved after 10000 cycles at 0.5 A/g.?2?Ti₃C₂T_x and polyaniline?PANI?composite materials?PNH,PH?were synthesized through electrostatic adsorption of PANI on the surface of MXene sheets in the liquid medium.The presence of then mild reaction condition suppress the oxidation of Ti₃C₂T_x flakes.Moreover,the synergistic effect of Ti₃C₂T_x and PANI prevents the restacking of the material,as Ti₃C₂T_x/PANI composite material with hierarchical porous increases the electrochemical performance.Moreover,the electrochemical performance of PNH is higher than of PH with same content.For example,the specific areas of PH and PNH increase to 19.72 and 22.91 m²/g respectively,the specific capacitance of PH and PNH could achieve 348 and 464 F/g at 1 A/g,which increased 13.4%and 51%than the specific capacitance of PANI respectively.Importantly composite material remain at 72%after5000 cycles at 5 A/g.