Investigation of Electrical and Electrochemical Properties of Ascorbic Acid-Treated SnO2/MXene Heterostructures for Hybrid Supercapacitors

Recently, Ti3C2Tx (MXene) and its heterostructures (HSs) with metal oxides have emerged as excellent materials for supercapacitors considering its distinctive electrochemical properties. However, environmental instability and poor interfacial interactions in two-dimensional (2D) Ti3C2Tx (MXene) and its HSs with metal oxides (due to surface group repulsion) have been a great challenge. Moreover, restacking of MXene passivates the active sites of the electrode. Here, we presented a novel approach to synthesizing ascorbic acid-treated MXene/SnO2 HS-based flexible electrodes for SCs. As-synthesized 3D SnO2 nanoflowers (NFs) were treated with ascorbic acid to activate their surface and provide a linkage site for MXene sheets. SnO2 NFs not only act as nanopillars between these layers but also maintain an appropriate space between the 2D layers and provide a 2D surface for charge storage. In conclusion, the self-assembly of these 2D–3D structures is retained, making it a more promising material for high-performance SC electrodes. The reported material not only presented an appreciable specific capacitance of 643 F/g but also demonstrated great electrochemical stability (only a 2% decrease) after 1000 cycles. In addition, the SnO2-anchored MXene showed great resistance against environmental humidity.