W‐Alloying Induced Long‐Period Stacking Ordering in Easily Delaminated (V, W) _4/3 Zr _2/3 AlC <i>i</i> ‐MAX and Excellent Antitumor Performance of (V, W) _1.33 C <i>i</i> ‐MXene Derivatives

Abstract V 4/3 Zr 2/3 AlC, as the only V‐based i ‐MAX phase reported up to now, cannot be delaminated using the conventional aqueous etching strategy. In the present work, by alloying W, the structure evolves from the C2/c monoclinic one in V 4/3 Zr 2/3 AlC to the nanoscale co‐existence of C2/c monoclinic and Cmcm orthorhombic ones in (V 0.2 W 0.8 ) 4/3 Zr 2/3 AlC i ‐MAX with the maximum W content. Especially, at the intermediate composition of (V 0.6 W 0.4 ) 4/3 Zr 2/3 AlC, the long‐period stacking ordered (LPSO) structure is first observed. Feasible delamination has been realized and the resultant Zr‐free (V 1− x W x ) 1.33 C i ‐MXene can be obtained for x ≥ 0.6, suggesting that W‐alloying is contributive to the delamination. A specific capacitance of 336.1 F g −1 at the current density of 0.5 A g −1 can be obtained in the (V 0.4 W 0.6 ) 1.33 C i ‐MXene under the extended voltage window of 1 V and highly stable performance for 10 000 charge/discharge cycles by compositing with the shell‐structured activated porous carbon. Besides, biological experiments have verified that (V 0.4 W 0.6 ) 1.33 C i ‐MXene significantly inhibits the growth, proliferation, and migration of hepatocellular carcinoma cells by inducing apoptosis, and regulates metabolism and immune response, possessing substantial targeted antitumor potential.