Exploring the Impact of Ni Doping in Tuning the Bandgap, Electronic, Optoelectronic and Photocatalytic Properties of ZnFe₂O₄

Abstract The exploration of semiconductor nanostructures utilizing mixed metal materials is an emerging area of study across fields including field‐effect transistors, chemical sensors, photodetectors, photocatalysts, and many more. In this study, Schottky diodes based on ZnFe 2 O 4 (ZFO) were constructed with an aim to tune their electronic and optoelectronic characteristics. Here, Ni doping facilitated the tuning of electronic properties, leading to a significant increase in the rectification ratio from 238 to 1172, along with a reduction in the potential barrier height from 0.67 V to 0.65 V. This is attributed to Ni's role as a charge carrier in ZFO, enhancing carrier concentration, confirmed by Mott‐Schottky analysis. The 5 mol % Ni‐doped ZFO also exhibited remarkable light sensitivity, with its rectification ratio surging to 1795 under illumination, four times that of the undoped version. Additionally, its photo‐sensitivity soared to 42.46 %, nearly quadrupling the undoped device's performance, and its power gain impressively climbed to 38.4 %, which is over twelvefold the undoped sample's output. Furthermore, the diode responds strongly to optical illumination, making this structure suitable for use as a photodiode or photosensor. Apart from that by employing a doping strategy, we achieved 64.61 % degradation of methylene blue dye under visible light in 120 minutes, compared to 36.85 % for the undoped sample. These indicate that hydrothermally synthesized Ni‐doped ZFO is promising for visible light‐driven multifunctional applications.