Mechanism of hydrogen plasma chemo-mechanical effect on properties of a MXene-based energy storage system

Direct-current hydrogen plasma (DCHP) parameters such as time of exposure, power, and temperature of treatment were examined in this study to find the optimum conditions regarding highest specific capacitance (sCap) enhancement of supercapacitor (SCs) electrodes fabricated by multi-layer nanostructure of Ti3C2Tx MXene. High sCap of 642 mF cm-2 was achieved in the three-electrode C-V measurements (more than doubled from the primary value of untreated MXene electrode). The underlying mechanism of the observed enhancement in plasmatreated SCs is discussed as well and DCHP was found to have three important effects on the MXenebased SCs: i) MXenes are mechanically delaminated and disturbed, ii) dangling bonds of MXene were increased leading to generation of Ti4+ ions, and iii) higher proportion of H+ functional groups were generated on the surface of the SC. All of these have important role in increment of capacitance and also the decrease in impedance and stability enhancement of the fabricated MXene-based SC are attributed to the proposed optimum recipe of plasma treatment. Therefore, this experimental feasibility study confirms successfulness of DCHP method in dramatic life-time enhancement of devices and development of new internet-of-things systems as well as durable wearable devices.