Oxygen vacancies facilitated visible light photoactivity of CdWO4 prepared by ionic liquid assisted hydrothermal method

In this demonstration, CdWO4 with wonderful visible light photoactivity was synthesized by a hydrothermal method with the assistance of 1-ethyl-3-methylimidazolium dihydrogen phosphate ([Emim]H2PO4) ionic liquid (IL). The existence of oxygen vacancies (OVs) was verified by X-ray photoelectron spectroscopy (XPS) and lowtemperature electron spin resonance (ESR). Scanning electron microscope (SEM), XPS and X-ray powder diffraction (XRD) results show that [Emim]H2PO4 affects the growth and surface properties of CdWO4. IL-CdWO4 has higher separation efficiency of photogenerated carriers under visible light irradiation than CdWO4, proven by surface photovoltage spectrum (SPS) and electrochemical measurements. Photoactivity of CdWO4 prepared was investigated using Rhodamine B (RhB) and tetracycline (TC) as simulated pollutants, the consequences exhibit that the visible light photoactivity of IL-CdWO4 toward destruction of RhB and TC is more than 3.45 and 6.78fold of that of CdWO4, respectively. In view of the observations, photocatalytic mechanism of IL-CdWO4 was proposed.

Automated summary

The demonstration showed that CdWO4 synthesized with the assistance of [Emim]H2PO4 ionic liquid exhibited excellent visible light photocatalytic activity. The IL-CdWO4 had higher separation efficiency of photogenerated carriers and greater degradation ability towards RhB and TC pollutants compared to CdWO4. The presence of oxygen vacancies in IL-CdWO4 was confirmed by XPS and ESR, and the growth and surface properties were affected by [Emim]H2PO4.