Experimental study of CuBi2O4 photocathode synthesized by spray pyrolysis and electrochemical deposition methods for visible light harvesting in photoelectrochemical cells

This research examined methods that are suitable, easy to fabricate, and low-cost for producing CuBi2O4 photocathodes for application in photoelectrochemical cells. Both spray pyrolysis and electrochemical deposition techniques were used to produce thin films for various types of semiconductor electrodes. The CuBi2O4 thin film was coated on fluorinedoped tin oxide (FTO) using spray pyrolysis and electrochemical deposition, followed by annealing in an oxygen atmosphere. X-ray diffraction (XRD) characterized the crystal structures, confirming them as Kusachiite. Scanning electron microscopy (SEM) analysis revealed that CuBi2O4 fabricated by electrochemical deposition exhibited smaller particles, while the spray pyrolysis method produced a plate-like structure. The optical properties were investigated using UV-visible reflection, and the energy bandgaps of the products were estimated using Tauc plots, showing slight differences. Chopped light voltammetry (CLV) was used to evaluate the photon conversion efficiency of the synthesized photocathodes. Results indicated that the photocathode made by electrochemical deposition responded better to light compared to the one made by spray pyrolysis. With 0.5 M Na2SO3 as a sacrificial agent, the highest photocurrent density obtained was 0.2 mA/cm², while with 0.5 M NaHCO3, the highest photocurrent was 0.5 µA/cm², indicating poorer performance.