Study on Ag 2 WO 4 /g-C 3 N 4 Nanotubes as an Efficient Photocatalyst for Degradation of Rhodamine B

Ag2WO4 is a typically noble metal based photocatalyst with highly efficient photocatalytic activity. However, due to photocorrosion, the pristine Ag2WO4 is prone to inactivation during illumination. Constructing composite photocatalyst may be a useful method to promote the stability of Ag2WO4. In this work, Ag2WO4/graphitic carbon nitride nanotubes (g-C3N4 NTs) composite photocatalyst was prepared by adopting an in-situ composite strategy. The photocatalytic performance of the samples was discussed by the degradation of rhodamine B under visible light, and the catalytic mechanism was also analyzed. The characterization results show that the photocatalytic efficiency of the as-prepared Ag2WO4/g-C3N4 NTs composite increases firstly and then decreases along with the increase of the Ag2WO4 content. When the theoretical molar ratio of Ag2WO4:g-C3N4 NTs reaches 3:2, the photocatalytic degradation efficiency achieves the optimal value, that is 92.4% within 20 min, which obviously exceeds 2.8% of pure Ag2WO4 and 48.9% of pure g-C3N4 NTs. Moreover, the separation and migration efficiency of photoelectron–hole pairs of the composites can be accelerated in comparison with pure samples. In addition, superoxide radicals and hydroxyl radicals play major roles in the photocatalytic degradation process.