The aim of this study was to investigate the photoelectrochemical responses of a BiVO₄ electrode and a BiVO₄ electrode modified with iron (30% Fe₂O₃) and silver (6% Ag) in solutions of perfluorooctanoic acid (PFOA) and Na₂SO₄. The experiments were conducted using both illuminated and non-illuminated electrodes, with an LED lamp as the light source. The methods employed included linear polarization, electrochemical impedance spectroscopy, chronoamperometry, and monitoring of open-circuit potential over time. Results obtained from linear polarization and chronoamperometry in 0.5 M Na₂SO₄ show that both electrodes exhibit photoactivity, with the modified electrode demonstrating enhanced photoactivity, as evidenced by higher photocurrents. Additionally, the modified electrode was tested in a solution of 0.01 mg/mL PFOA in 0.5 M Na₂SO₄, where the lower photocurrents and significant increase in current above 1.2 V in the presence of PFOA indicate different behavior of the electrode in the presence of PFOA compared to pure Na₂SO₄. Electrochemical impedance spectroscopy revealed higher impedances in the absence of light, indicating good photoactivity of the material, with the modified BiVO₄ showing superior photoactivity. Monitoring the open-circuit potential further confirmed the photoactivity of the electrodes, with the observed shift to more negative values suggesting that the tested materials are n-type semiconductors. However, this method also indicated different response of modified BiVO₄ in Na2SO4 and PFOA solutions, which contrasts with the results obtained from linear polarization.