Designing visible-light-driven direct Z-scheme Ag 2 WO 4 /WS 2 heterojunction to enhance photocatalytic activity

The direct Z-scheme Ag2WO4/WS2 photocatalysts had been fabricated by using a deposition method. Experimental results indicated that WS2 nanosheets could improve the photocatalytic activity, light absorption and recyclability of Ag2WO4 under the visible light irradiation. The degradation efficiency of the as-obtained Ag2WO4/WS2 hybrids for rhodamine B displayed first increasing and then decreasing with increasing the usage of WS2 nanosheets. When the usage of WS2 was 15 wt%, in 120 min, it reached the maximum of 97.8%, which was higher than 17.8% of pure Ag2WO4. Moreover, after three cycles of the degradation, the as-prepared hybrids still possessed 94.4% of the degradation efficiency, which increased by 1211.1% compared with pure Ag2WO4. Moreover, superoxide and hydroxyl radicals played major role during the process of photocatalytic degradation. The enhanced photocatalytic activity could be ascribed to the formation of direct Z-scheme photocatalytic system between Ag2WO4 and WS2.