Two-dimensional non-van der Waals V8C7/V2O3 heterostructure derived from V2AlC MAX phase for superior sodium and zinc batteries

Although two-dimensional (2D) non-van der Waals (non-vdW) heterostructures with intriguing physical and chemical merits have the potential application in rechargeable batteries, they still lack valid synthetic methods due to their three-dimensional chemical bonding characteristics. Here, a facile one-step method to synthesize the 2D non-vdW V 8 C 7 /V 2 O 3 heterostructure based on the conversion of V 2 AlC MAX phase in the molten copper chloride is developed. Accompanied with the aluminium layer etching, the V 2 AlC precursor is transformed into the intermediate product (i.e., 2D non-vdW V 8 C 7 ). Interestingly, an operando conversion from the intermediate 2D non-vdW V 8 C 7 to the final 2D non-vdW V 8 C 7 /V 2 O 3 heterostructure is achieved via the extrinsic adsorbed oxygen. Similarly, other types of halogenated salts, including copper bromide and cuprous iodide, can also be as etchants to obtain the 2D non-vdW V 8 C 7 /V 2 O 3 heterostructure. Owing to the 2D character and unique hetero-structure, the obtained 2D non-vdW V 8 C 7 /V 2 O 3 heterostructure can be used as a superior cathode of sodium metal batteries. Meanwhile, the resultant 2D non-vdW V 8 C 7 /V 2 O 3 heterostructure can also enhance the whole performance of aqueous zinc-iodine batteries. This new construction method of 2D non-vdW heterostructures facilitates the development of high-performance rechargeable batteries.