Enhancing Ag2MoO4 catalytic activity: An investigation on synthesis, characterization, and application in catalytic ozonation reactions

Silver molybdate (Ag2MoO4) has promising results in photocatalysis and Fenton-like reactions, but its use in catalytic ozonation and the role of its different crystalline phases remain poorly understood. The understudied metastable alpha-phase remains a challenge in terms of production, characterization, and catalytic properties, due to its tendency to convert to the stable beta-phase. This study investigates the optimized synthesis of the alpha-phase using a face-centered central composite experimental design by varying PVP concentration and pH. Results revealed that significant effects of synthesis conditions on alpha-phase formation and optical-textural properties. Increasing pH negatively affects textural properties and crystalline phases distribution, while the interaction between PVP concentration and pH proportionally improves optical properties. The statistical analyses predicted a maximum alpha-phase formation of 71 % (PVP: 2.9 mmol L-1 and pH: 4.9) externally from the parameters range applied. Silver molybdate produced under pH > 4.5 showed catalytic activity to remove trimethoprim in aqueous suspensions. Moreover, particle morphology strongly influenced on the catalytic activity, with well-structured particles achieving up to 76 % removal of trimethoprim. Higher crystallinity had a greater impact on catalysts activity. Thus, strict control during alpha-Ag2MoO4 synthesis is crucial, emphasizing the dependence of catalytic activity on synthesis conditions.

Automated summary

This study successfully synthesized the alpha-phase of silver molybdate and investigated the relationship between synthesis conditions and optical-textural properties. The results showed that synthesis conditions significantly influenced the formation of the alpha-phase and its optical properties. Increasing pH had a negative effect on textural properties and crystalline phase distribution, while the interaction between PVP concentration and pH improved optical properties.