MXene Surface Functional Groups Regulation: Enhancing Area Capacitance of Divalent Zinc Ion Micro-Supercapacitor

As an emerging two-dimensional material, MXene is widely used in the field of energy storage, especially for micro-supercapacitors (MSC). After the etching of the original Ti ₃ AlC ₂ , the obtained surface of Ti ₃ C ₂ T _x MXene has a grand number of functional groups, such as (–F, –OH, –O). In this paper, we introduced bacterial cellulose(BC) with a amount of functional groups to widen the layer spacing, so that more metal ions are adsorbed on the surface of MXene, then KOH solution was added for treatment mixed solution of MXene/BC. We confirmed by FT-IR that a grand number of groups were present on the surfaces of Ti ₃ C ₂ T _x and BC, and then characterized by XPS and found that the oxygen functional group strength on the surface of the treated MXene/BC composite film was significantly increased compared to the untreated MXene/BC composite film. The electrochemical performance test showed that the composite film treated with KOH solution as the MSC electrode had an area capacitance of 223 mF cm ⁻² and an area energy density of 42 μ Wh cm ⁻² , which was better than composite film electrode of the MSC without KOH treatment (area capacitance of 161 mF cm ⁻² and area energy density of 31 μ Wh cm ⁻² ).