Plasmonic Au-Assisted g-C₃N₄/CeO₂ Heterojunction for Enhanced Photocatalytic Breakdown of Organic Pollutants

We demonstrate and rationalize the effect of Au nanoparticles (NPs) on the hierarchical g-C₃N₄/CeO₂ heterojunction. g-C₃N₄/CeO₂ decorated with monodispersed plasmonic Au NPs was synthesized. Detailed analyses showed that CeO₂ nanocubes and monodispersed Au NPs were evenly distributed over the 2D g-C₃N₄ surface, forming a robust interface enriched with abundant active sites. The structure enabled efficient separation of photogenerated charge carriers and exhibited an enhanced optical response. Further, the well-designed g-C₃N₄/CeO₂/Au heterojunction demonstrated an improved photocatalytic performance in degrading the Rhodamine B (RhB) dye under visible light irradiation with the rate constant of 0.0483 min^-1, twice higher than for the binary g-C₃N₄/CeO₂ composite. In addition, the optimal catalyst showed a high photocurrent response (2.04 mA/cm²) in photoelectrochemical water splitting with a low charge transfer resistance and overpotential. By anchoring monodispersed Au NPs, we enhanced the surface properties and achieved efficient charge carrier separation, boosting the overall material performance.