CsCl−Flux Synthesis of Titanium Oxynitride Ti2.85O4N for Photocatalysis

The molten salt method is a key approach for preparing high−performance metal oxide photocatalysts, though its use in metal oxynitrides remains limited. In this work, we successfully synthesized titanium oxynitride Ti2.85O4N using CsCl flux method and evaluated the photocatalytic properties. The impact of CsCl addition at different synthesis stages was systematically studied. The addition of CsCl significantly enhanced the crystallinity of the oxynitrides, reducing defects and improving the overall material quality. Specifically, Ti2.85O4N−Cl−Cl, which incorporated CsCl during both precursor synthesis and oxynitride synthesis, exhibited the highest visible−light photocatalytic activity. In photocatalytic tests, Ti2.85O4N−Cl−Cl demonstrated a remarkable degradation rate of 77% for methylene blue under visible light irradiation within 120 minutes, which is approximately 1.97 times higher than that of the Cs0.68Ti1.83O4 precursor. The reaction rate constant for Ti2.85O4N−Cl−Cl was determined to be 0.00899 min−1, indicating efficient electron-hole separation and utilization of visible light. Our findings open a new direction for high−performance oxynitride synthesis, highlighting the potential of the molten salt method in enhancing the photocatalytic properties of metal oxynitrides.