Controlled growth of a 2D/2D heterojunction for high-performance sodium ion storage†

We propose a van der Waals epitaxial growth method and successfully construct a 2D/2D heterostructure based on graphdiyne (GDY) and Ti₂C₃T_x. In our preparation process, the insertion of monomers and subsequent cross-coupling reactions guarantee the successive and conformal growth of GDY on the Ti₂C₃T_x nanosheets, resulting in the production of large-scale 2D/2D heterojunctions. This new heterojunction highlights the structural advantages and effectively prevents the planar restacking of the Ti₂C₃T_x nanosheets. It also provides numerous accessible channels and active spots for rapid ion transportation and Na⁺ storage. Electrochemical tests demonstrate that these enriched heterojunctions significantly enhance the kinetic behavior for storing the Na⁺, resulting in a six-fold increase in the specific capacity. Our results show that the controllable growth of GDY has significant advantages in the preparation and assembly of 2D/2D heterojunctions. These heterojunctions have great potential in the field of electrochemical energy storage.