<p>Industrial pollution, particularly from textile dyes and heavy metals, significantly threatens environmental water sources. This study addresses the issue by exploring an advanced photoreduction method: photocatalysis. We synthesized batches of green ZnFe binary metal oxide nanocatalysts (ZnFe-A, ZnFe-B, ZnFe-C) with varying zinc precursor concentrations. Further evaluated their catalytic performance in reducing Cr(VI). Among them, ZnFe-A exhibited exceptional catalytic properties, outperforming previous studies in Cr(VI) reduction. The optimization investigation demonstrates that the significant role of factors like initial Cr loading and variation in pH range strongly affect the photocatalysis reaction and ultimately Cr(VI) reduction. Upon light exposure, ZnFe-A with its smaller bandgap (1.69 eV) readily promotes electron excitation, resulting in electron-hole formation and driving subsequent oxidation and reduction reactions. The ZnFe-A catalyst exhibited a remarkable reduction of 20 mg/L Cr(VI) in just 15 min, representing a substantial advancement. Kinetic analysis confirmed that a pseudo-second-order reaction mechanism best describes the process, underscoring the efficiency of the catalyst. Reusability studies demonstrated its consistent performance over five consecutive cycles, with 82.98% efficiency maintained even after the fifth cycle, highlighting its practical utility in environmental remediation for heavy metal reduction. Beyond photocatalysis reduction, ZnFe-A also exhibited promising electrochemical performance for energy storage, delivering a specific capacitance of 432 F/g at 1 A/g, and energy density of 9.6 Wh/kg and power density of 198 W/kg. Even after 10,000 charge-discharge cycles, the electrodes retained 69% of their initial capacitance with ~ 80% coulombic efficiency, confirming their potential as a stable and efficient supercapacitor material.</p> Graphical Abstract <p></p>