Sustainable Synthesis of Cr7C3, Cr2AlC, and Their Derived Porous Carbons in Molten Salts

Carbide-derived materials including porous carbon and MXenes have received tremendous interest in recent years. Herein, we report a sustainable route direct from low-cost metal oxides/carbon (MOs/C) powders to metal carbides (MCs) and then to porous carbide-derived carbons (CDCs). With the assistance of a solid oxide membrane (SOM), Cr7C3 and Cr2AlC have been first synthesized from Cr2O3/C and Cr2O3/Al2O3/C powder mixtures, respectively. The synthesis pathway typically comprises electrochemical compounding, electrochemical reduction, and in situ carbonization processes. The Cr7C3 and Cr2AlC with similar homogeneous nodular structure have been further in situ electrochemically converted into porous CDC materials. The as-prepared CDCs with amorphous and graphitic structures are hierarchical meso-/macroporous carbon materials. Besides, the CDCs as an anode for lithium ion batteries were evaluated for their electrochemical performance. The results show that the discharge capacity of Cr2AlC-CDC can stay at 248 mAh g–1 after 100 cycles at 100 mA g–1, demonstrating stable cyclic performance. The molten-salt electrochemical reduction–etching process provides a new method for synthesizing various CDC materials.