Three-dimensional Ni-Cr-MOF/CNT hybrid electrode on nickel foam for efficient water splitting and electrochemical capacitor applications.

The growing demand for clean and sustainable energy technologies has accelerated the development of multifunctional electrode materials for both energy conversion and storage. In the present work, a binder-free Ni-Cr-MOF/CNT hybrid electrode was grown on nickel foam (NF), then fabricated, and investigated for overall water splitting and supercapacitor applications. The structural, morphological, and surface properties were examined using XRD, FTIR, XPS, SEM, EDX, and elemental surface mapping, confirming the successful formation of porous and conductive hybrid architecture with uniformly distributed active components and improved charge-transfer behavior. In alkaline medium, the NF-supported Ni-Cr-MOF/CNT electrode exhibited efficient bifunctional electrocatalytic activity, requiring low overpotentials of 250 mV for HER and 310 mV for OER at 10 mA cm-2 in a solution of 1.0 M KOH. The corresponding Tafel slopes of 123 mV dec-1 for the HER and 146 mV dec-1 for the OER indicated favorable reaction kinetics, while stable operation for 12 h demonstrated good durability. For supercapacitor application, the electrode delivered a high specific capacitance of 940 F g-1 at 0.5 A g-1, maintained 80% rate capability from 0.5 to 5 A g-1, and retained 87% of its capacitance after 10 000 cycles. These enhanced performances are attributed to the synergistic effect of redox-active Ni-Cr-MOFs, the conductive CNT network, and the three-dimensional nickel foam substrate. The results highlight the Ni-Cr-MOF/CNT/NF electrode as a promising dual-functional material for efficient water splitting and high-performance energy storage.