A simple approach to synthesis Cr2CTx MXene for efficient hydrogen evolution reaction

Two-dimensional chromium carbide-based MXenes are predicted as an efficient catalyst for the hydrogen evolution reaction (HER). However, the lack of an effective approach to fabricate this promising material remains an impediment to practical applications. Herein, a simple strategy is proposed to synthesis Cr2CTx ultrathin structures from Cr2AlC MAX. The high-resolution analytical scanning transmission electron microscopy (STEM) corroborated with X-ray diffraction and scanning electron microscopy demonstrates that the Al atomic layers have been detached from the pristine MAX structure. Further atomic-resolution STEM confirms that the ultrathin Cr2CTx sheets with fluoride-free surface, nanostructured Cr2CO2, and Al2O3 phases are originated as by-products. The electrochemical test shows that the fabricated Cr2CTx composite with minimal Al2O3 have a good performance for hydrogen evolution reaction and exceed even that of Pt sheet catalyst at high current density. Moreover, high stability of more than 160 h without attenuation was observed to be better than the other MXenes catalytic performer to date. This work paves a gentle route to fabricate Cr2CTx MXene and demonstrates the potential application for HER.