In-situ construction of g-C3N4/Mo2CTx hybrid for superior lithium storage with significantly improved Coulombic efficiency and cycling stability

Abstract

Mo2CTx MXene, obtained by etching Ga from the Mo2Ga2C, is theoretically predicted to possess high electrochemical activity. However, the preparation of Mo2CTx remains challenging due to the difficultly of traditional HF etching. Increasing the exfoliation degree and constructing the protection layer of Mo2CTx not only can offer rich active sites but also suppress side reaction, which has been considered as efficient approaches to improving its electrochemical performance. In this work, a facile in-situ strategy was developed to synthesize the graphitic carbon nitride/Mo2CTx (g-C3N4/Mo2CTx) hybrid, smartly employing the conversion from urea to g-C3N4 to realize the exfoliation degree of Mo2CTx MXene and simultaneously build a protection layer. As expected, the abundant exposed MXene layers are believed to provide rapid diffusion pathways for the ions transport as well as rich active sites for lithium storage. As a result, the target g-C3N4/Mo2CTx hybrid exhibits a much higher Coulombic efficiency (70.8%) and superior lithium storage performance (525.8 mAh g−1) compared with pure Mo2CTx (19.2% and 101.4 mAh g−1). Generally, this synthesis strategy presented in this study paves a new way for the fabrication of MXene based hybrid with high performance for lithium storage.