Vertically Aligned NiMoO ₄ -MXene Heterostructured Nanosheet Arrays for High-Rate Hybrid Supercapacitors

Binary transition metal oxides (BTMOs) have emerged as promising electrode materials for supercapacitors due to their high theoretical capacity and rich redox activity. However, their practical applications are hindered by internally low electrical conductivity and structural degradation during the cyclic process. Herein, a synergistic strategy is reported for enhancing the electrochemical performance of NiMoO 4 through hybridization with Ti 3 C 2 T x MXene. The vertically aligned nanosheet array composite structure (NiMoO-MX/NF) on nickel foam is prepared via a three-step hydrothermal process. The Ti 3 C 2 T x MXene not only repairs structural defects but also introduces additional electroactive sites and a conductive network, thereby accelerating electron transport and ion diffusion. Electrochemical measurements reveal that NiMoO-MX/NF delivers a high specific capacity of 942.0 C g –1 at 1 A g –1, significantly higher than that of NiMoO/NF (498.2 C g –1 ), while still maintaining a high specific capacity of 514.0 C g –1 at 40 A g –1 . It also exhibits exceptional rate capability (54.6% capacity retention at 40 A g –1 ) and cycling stability (78.5% retention after 5000 cycles). When assembled into a hybrid supercapacitor with nitrogen-doped graphene as the negative electrode, the device achieves a specific energy of 38.36 Wh kg –1 at 800 W kg –1 . This work demonstrates the effectiveness of highly conductive MXene materials in optimizing the charge storage performance of BTMOs, offering a scalable strategy for developing high-performance electrode materials for next-generation energy storage systems.