Design of Ag-modified Ni/Cr-MOF/carbon felt electrode for dual energy conversion and storage applications

Abstract

Multifunctional electrodes for both energy conversion and storage are highly desirable for next-generation clean-energy technologies. Herein, a Ag@Ni–Cr-MOF/CF electrode was fabricated by integrating Ni- and Cr-based MOF phases with silver species on a conductive carbon felt substrate. The porous carbon felt provided a flexible three-dimensional support, while Ag enhanced electrical conductivity and charge-transfer efficiency. XRD, FTIR, TGA, SEM, EDX, and elemental mapping confirmed the successful formation of the hybrid structure and elemental distribution. The Ag@Ni–Cr-MOF/CF electrode exhibited efficient bifunctional activity toward alkaline water splitting, requiring overpotentials of 260 mV for HER and 200 mV for OER at 10 mA cm−2. The corresponding Tafel slopes of 87 and 68 mV dec−1 indicated favorable reaction kinetics, while stable operation for 15 h confirmed good durability. As a supercapacitor electrode, it delivered a specific capacitance of 780 F g−1 at 0.5 A g−1, retained 80.8% capacitance when the current density increased to 5 A g−1, and maintained 82% capacitance after 12 000 cycles at 10 A g−1. This enhanced performance arises from the synergistic effects of Ni–Cr-MOF redox-active sites, Ag-assisted conductivity, and the interconnected porous carbon felt framework. These results highlight Ag@Ni–Cr-MOF/CF as a promising electrode for integrated water-splitting and supercapacitor applications.