Plasmonic p-n heterojunction of Ag/Ag2S/Ag2MoO4 with enhanced Vis-NIR photocatalytic activity for purifying wastewater

The sensitivity of photocatalysts to visible (Vis) and near infrared (NIR) light has been attracting considerable attention owing to its high utilization efficiency of solar energy. Herein, we have successfully constructed Ag/Ag2S/Ag2MoO4 p-n heterojunctions by hydrothermal method, which displays obvious surface plasmon resonance (SPR) and wide photoabsorption range from Vis to NIR light (400-900 nm). Ag/Ag2S/Ag2MoO4 exhibits the weakest photoluminescence (PL) spectroscopy and highest photocurrent intensity, indicating greater separation efficiency of photogenerated electron-hole pairs compared with Ag/Ag2S and Ag/Ag2MoO4. Under the visible light irradiation, Ag/Ag2S/Ag2MoO4 can remove 99% RhB, 100% MB, 83% TC and 77% Cr(VI), higher than that of Ag/Ag2S or Ag/Ag2MoO4. Importantly, with 808 nm laser as light source, Ag/Ag2S/Ag2MoO4 shows excellent NIR-driven photocatalytic activity (62% RhB, 58% MB, 52% TC and 50% Cr(VI)), compared to Ag/Ag2S or Ag/Ag2MoO4. The excellent photocatalytic performance of Ag/Ag2S/Ag2MoO4 under Vis or NIR light roots from high separation efficiency of photogenerated carriers derived from the construction of Ag/Ag2S/Ag2MoO4 p-n heterojunctions. Additionally, Ag/Ag2(S)/Ag2MoO4 can be easily recycled with high stability. Therefore, Ag/Ag2S/Ag2MoO4 can be employed as efficient and recyclable Vis-NIR-driven photocatalyst for the purification of wastewater.