Enhanced visible-light-driven photocatalytic degradation of acetaminophen over CeO₂/I, K-codoped C₃N₄ heterojunction with tunable properties in simulated water matrix

A novel visible-light-active photocatalyst consisting of CeO₂ nanoparticles and I, K-codoped graphitic carbon nitride (IK-C₃N₄) was engineered using urea, potassium iodate and cerium nitrate as raw materials via a facile pyrolysis method. The CeO₂/IK-C₃N₄ composite was then applied for the rapid elimination of acetaminophen (ACT) under 465-nm visible light irradiation in aqueous solutions at different environmental parameters. The electronic images clearly showed that 5 – 20 nm CeO₂ can be tightly attached onto IK-C₃N₄. The charge imbalance of Ce element as well as oxygen vacancy of CeO₂/IK-C₃N₄ enhanced the photocatalytic activity of the composite. Moreover, the optical property and bandgap were easily tuned by changing the CeO₂ amounts. At optimum composition of 15 wt% CeO₂, the bandgap of CeO₂/IK-C₃N₄ can narrow down to 2.38 eV. The photocatalytic activity of CeO₂/IK-C₃N₄ heterojunction toward ACT degradation is dependent on CeO₂ amounts and environmental parameters including pH, anions and initial ACT concentration. The calculated pseudo-first-order rate constants ranged from 0.039 to 0.051 min⁻¹. The radical species trapping experiments confirmed that O₂^[rad]− and h⁺ play significant roles in ACT degradation. Thus, enhanced photodegradation of ACT is explained by type-II heterojunction mechanism. These findings provide a promising strategy of combining CeO₂ and doped g-C₃N₄ for the effective removal of emerging pollutants under visible light irradiation, which can open a new route to synthesize novel heterojunction with high photoactivity for water purification and environmental sustainability.