Electrochemical Pathway to Large Flake Ti3C2T x MXenes via Controlled Aluminum Dissolution for High Performance Supercapacitors

Conventional MXene synthesis relies on hazardous concentrated HF, raising safety, and environmental concerns despite the outstanding electrical and mechanical properties of the resulting MXenes. Here, we demonstrate an electrochemical etching protocol using a carbon cloth working electrode and HBF4/water electrolyte to selectively remove Al from Ti3AlC2 MAX phase. Applying a constant potential of 1 V drives anodic Al dissolution via a controlled redox process, minimizing HF generation while preserving the Ti-C backbone. The resulting Ti3C2Tx nanosheets exhibit substantially larger flake sizes compared to conventionally etched MXene, while retaining their hexagonal structure. Structural, vibrational, chemical, and morphological evidence confirms that Al is selectively etched under electrochemical bias. Furthermore, the electrochemically synthesized Ti3C2Tx was employed as an electrode material for electrochemical energy storage applications. The electrochemically etched MXene (EDM-1V) exhibits a high areal capacitance of ∼164 mF cm–2 at a scan rate of 10 mV s–1 and promising cycling stability, outperforming both electrochemically etched at 0 V (EDM-0V) and conventionally HF etched MXene (HF-DM). This work provides a safe, scalable, and mechanistically guided electrochemical route that positions Ti3C2Tx as a promising candidate for energy storage technologies.