Tailoring Surface Oxygen Vacancies in Tungsten Oxides for Surface Plasmon Resonance-Enhanced Near-Infrared Photoreduction of Cr(VI)

Semiconductor photocatalysis based on nanosized photocatalysts is an emerging solar-utilization technology with great potential in wastewater treatment. The challenge is developing highly efficient and low-cost photocatalysts. Smartly tailoring oxygen vacancies (OVs) is a key step because redundant OVs could serve as the combination centers for electron–hole pairs. Herein, we choose the tungsten oxide (WO 3 ) crystal as the pristine system and modify its surface using ultrathin layered indium zinc sulfide (ZnIn 2 S 4, ZIS) nanosheets to generate in situ surface OVs. The experimental results reveal that ZIS-modified WO 3 shows strong near-infrared (NIR) absorption from the surface plasmon resonance (SPR) induced by the generated surface OVs. Meanwhile, the high crystalline and nanorod-like morphology of WO 3 can be well maintained, which is beneficial for the transmission and separation of photogenerated carriers. As a result, ZIS-modified WO 3 shows enhanced photoreduction of Cr(VI) with a reduction efficiency of 90.39% under NIR light in 100 min, and the reaction rate ( k ) is ∼17 times that of pristine WO 3 . This work highlights the important role of tailoring surface OVs and provides a new perspective for alleviating Cr(VI) pollution by highly efficient SPR semiconductor photocatalysts.