Enhanced 4-chlorophenol Degradation under Visible and Solar Radiation through TiO₂/g-C₃N₄ Z-Scheme Heterojunction

The efficient remediation of the persistent organic pollutant known as 4-chlorophenol (4CP) in aqueous effluent presents a challenge for a wide array of industries due to its elevated toxicity and resistance to natural degradation processes. This study proposes the development of a hybrid photocatalyst composed of titanium dioxide (TiO2) and graphitic carbon nitride (g-C3N4), aiming to increase the efficiency of photocatalytic degradation of 4CP under solar and visible radiation through the formation of Z-scheme heterojunction between the semiconductors. The results showed that the synthesis of the TiO2/g-C3N4 binary material was successful by X-ray diffractometry and infrared spectrometry. Furthermore, the addition of g-C3N4 to TiO2 led to optical and morphological modifications, such as the pore volume increase and gap energy of TiO2/g-C3N4. Concerning the photocatalytic evaluation, the main results indicate that photocatalytic activity under visible radiation of the TiO2/g-C3N4 improved by 44.8% compared to pure TiO2, whereas an improvement of 30.5% was obtained under simulated solar radiation. This improvement in efficiency was further corroborated by chronoamperometry tests, which demonstrated a higher photocurrent generation for the TiO2/g-C3N4. The radical generation mechanism suggested the creation of an effective Z-scheme heterojunction between the semiconductors, as the formation of both hydroxyl and superoxide radicals was observed.