WO₃/MIL-125 (Ti) composite material for enhancing the reduction of Cr(vi) under visible light

In wastewater containing heavy metals, Cr(vi) is a potentially toxic metal, mainly derived from production and processing processes such as textile printing, dyeing, ore mining, battery applications, metal cleaning and electroplating. WO₃ is widely used in photocatalytic degradation and reduction, and its utilization rate of visible light is high. However, the rapid recombination of photogenerated electron-hole pairs of WO₃ limits its use. In this work, the composite material (WxMy) of WO₃ and MIL-125 (Ti) was prepared by the ball milling method, and the catalyst was used to photocatalytically reduce Cr(vi). After using W90M10 as a photocatalyst for 50 min, the reduction rate of Cr(vi) can reach 99.2%, and the reduction rate is 2.3 times that of WO₃. After 5 cycles of use, the reduction rate can still reach 91.3%. It is mainly due to the formation of a II-type heterojunction between WO₃ and MIL-125 (Ti), which promotes the separation of photogenerated electron-hole pairs, thus improving the efficiency of photocatalytic reduction of Cr(vi).