Quantitative Analysis of Degree of Nitridation of Ta2O5 to TaON Particles and their Photocatalytic Oxygen Evolution Properties

Oxynitride or nitride photocatalysts are typically synthesized by heating oxide precursor particles at high temperatures under NH3 flow. Although there are numerous reports on optimizing the nitridation conditions for different materials, the detailed nitridation mechanism is still unclear. In this study, the nitridation of Ta2O5 to TaON was investigated. The degree of nitridation was quantitatively analyzed using the change in the weight of a powder after nitridation. Three regions were identified in the nitridation process for different nitridation times and NH3 flow rates. Moreover, the initial stage of the nitridation process (linear region) was formulated for the first time. Structural analysis, absorption properties, and oxygen evolution activity were combined with the degree of nitridation to reveal the relationship between the nitridation process and photocatalytic activity. The results of this work are useful for understanding and improving the photocatalytic properties of oxynitrides.