Facile green synthesis of 2D hexagonal MoO3 for selective detection of ammonia at room temperature

A facile green synthesis of 2D MoO3 has been demonstrated for detection of ammonia at room temperature. The bulk MoO3 was exfoliated in water via ultrasonication assisted liquid exfoliation technique. Interestingly, the resulting MoO3 nanosheets exhibited metastable hexagonal phase unlike the base material (orthorhombic (alpha) MoO3), as confirmed by different characterization techniques. The phase stability has been confirmed by annealing studies and Thermo-gravimetric analysis (TGA) and the complete transformation back to alpha-MoO3 was observed at 300 degrees C. The phase transformation has been attributed to the intercalation of water molecules in the 2D layers of MoO3. The dispersion in organic solvents like ethanol further proves this argument as no phase transformation was observed in the later. The exfoliated hexagonal MoO3 based devices responded fairly well towards ammonia in the concentration range of 0.3 ppm to 5 ppm at room temperature and also superior to the ones prepared in Ethanol medium.

Automated summary

The study presents a facile green synthesis method for 2D MoO3 for detecting ammonia at room temperature. MoO3 nanosheets with a metastable hexagonal phase were obtained by liquid exfoliation in water using ultrasonication. The phase transformation of MoO3 was attributed to water molecules intercalation in the 2D layers, resulting in excellent response towards ammonia in device tests.