Hydrothermal synthesis of MXenes in alkali environment and development of MXene/PEDOT:PSS composite electrodes for supercapacitor applications

Abstract MXenes are conventionally synthesized by a top-down selective etching process using toxic fluoride-based chemicals. Here, we report a unique one-pot method for fabricating multilayer structures of Ti 3 C 2 OH MXene by etching Ti 3 AlC 2 with alkali. MXene is synthesized by hydrothermal etching of MAX phase (Ti 3 AlC 2 ) using relatively non-toxic alkali (potassium hydroxide) solutions. The quality of synthesized MXenes was studied as a function of alkali concentration, precursor pre-treatment, and total reaction time. Increase in alkali concentration exhibits improved etching capability, yield, and stability of MXene, whereas pre-treatment of precursor at elevated temperature and longer reaction time shows detrimental effects on the quality of synthesized MXene with formation of titanate nanofibers. Moreover, we also fabricated MXene/poly(3,4-ethylenedioxythiophene) polystyrene sulfonate composite aerogels and demonstrated its suitability as active electrode material for supercapacitor applications. Graphical abstract