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• Development of p-n hetero junction ZCO@Ni-MOF-based electrode via hydrothermal process. • The performed electrochemical studies are in clear agreement to each other and supported with Ex-situ XRD and operando EIS analysis. • Asymmetric supercapacitors exhibiting the performance up to an energy density of 13.6 Wh kg−1at a power density of 255 W kg−1. • Efficient oxygen evolution reaction performance producing over potential of 340 mV at current density of 50 mA cm−2. The stable structure and material combination design significantly improve the performance of electrochemical energy storage and water splitting. In the present study, we developed a ZCO@Ni-MOF core-shell structure over a nickel foam electrode, which is synthesized through a two-step hydrothermal treatment. The developed material is comprehensively analyzed to confirm structural, chemical, electronic, surface, and morphological characteristics using X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, scanning electron microscope (SEM), and transmission electron microscope (TEM). Electrochemical investigations using a three-electrode system revealed that ZCO@Ni-MOF demonstrated an impressive specific capacitance of 1800 F g−1 at a current density of 2 A g−1 in a 1 M KOH electrolyte. The electrochemical findings are consistent across various electrochemical techniques. Furthermore, in-depth studies regarding p-n junction formation, interlayer spacing, and reaction kinetics studies are briefly analyzed with Mott-Schottky, Ex-situ XRD, and operando impedance studies. Moreover, an asymmetric supercapacitor (ASC) is assembled with ZCO@Ni-MOF as the positive electrode and activated carbon as the negative electrode in a Swagelok cell. This configuration demonstrated an energy density of 13.6 Wh kg−1 at a power density of 225 W kg−1. The ASC exhibited performance by retaining 91 % of its initial capacity even after 1500 cycles. For practical demonstration, two ASCs are fabricated and assembled in series to light up an LED, and the light-up duration is analyzed. For the oxygen evolution reaction (OER) study, the ZCO@Ni-MOF-based electrode exhibited activity with a lower overpotential of 340 mV (50 mA cm−2) in an alkaline environment and was responsible for stability for about 10 h. This combination reiterates the promising material aspects in energy storage and conversion devices, instilling hope for its potential applications. [Display omitted] [ABSTRACT FROM AUTHOR]