Enhancing the Photoelectrochemical Performance of a Superlattice p–n Heterojunction CuFe2O4/ZnFe2O4 Electrode for Hydrogen Production

A p–n heterojunction film consisting of p-type CuFe2O4 and n-type ZnFe2O4 was fabricated in this study. The n-type ZnFe2O4 film was deposited on a stainless steel substrate using the spray pyrolysis method, after which a top layer of p-type CuFe2O4 thin film was deposited and annealed. Characterization techniques, such as X-ray diffraction, scanning electron microscopy, UV–Vis diffuse reflectance spectroscopy, and photoluminescence, confirmed the formation of a superlattice p–n heterojunction between CuFe2O4 and ZnFe2O4. Photoelectrochemical measurements were conducted to investigate the photoelectrochemical properties of the samples, resulting in a photocurrent of 1.2 mA/cm2 at 1.5 V (vs. Ag/AgCl) under illumination from a 100-watt LED light source. Utilizing the p–n junction of CuFe2O4/ZnFe2O4 as a photoanode increased the hydrogen production rate by 30% compared to that of the dark measurement. This enhancement in performance was attributed to the potential barrier at the p–n heterojunction interface, which improved the separation of photoinduced electron–hole pairs and facilitated a more efficient charge transfer. Additionally, coating the stainless steel electrode with this ferrite sample improved both the corrosion resistance and the stability of hydrogen production over extended operation times.