Fabrication and Characterization of BaMoO4-Coupled CaWO4 Heterojunction Micro/Nanocomposites with Enhanced Photocatalytic Activity Towards MB and CIP Degradation

The polyacrylamide gel method combined with low- temperature calcination technology (PGMCLCT) have been successfully used to synthesize BaMoO4-coupled CaWO4 heterojunction micro/nanocomposites (BCCHMNs) with excellent photoluminescence properties and enhanced photocatalytic activity towards methylene blue (MB) and ciprofloxacin (CIP) degradation. The photoluminescent properties and photocatalytic activity of BCCHMNs strongly depend on the special interfacial contact between BaMoO4 and CaWO4. Phase structure, functional group, oxidation state, and microstructure analysis confirm that the BCCHMNs contains only BaMoO4 and CaWO4 phases, without any other impurities, and that the interface between BaMoO4 and CaWO4 forms a type II band arrangement heterojunction. The BaMoO4/10 wt% CaWO4 heterojunction micro/nanocomposites exhibit two obvious emission peaks at 470 and 490 nm under the excitation wavelength of 311 nm. The BaMoO4/15 wt% CaWO4 heterojunction micro/nanocomposites exhibit highest photocatalytic activity of about 95.433% for the degradation of MB and 97.886% for the degradation of CIP, due to the high charge transfer and separation efficiency, and optimal initial dye or CIP concentration and photocatalyst content are 20 mg/L and 1 g/L, respectively. With the increase of CaWO4 mass percentage, the photoluminescence and photocatalysis of BCCHMNs showed an opposite trend. The dependence of photoluminescence and photocatalysis on special interface contact and adsorbed oxygen provides an idea to study other types of metal oxide heterojunctions for the degradation of antibiotics.