Copper tungstate (CuWO4)/graphene quantum dots (GQDs) composite photocatalyst for enhanced degradation of phenol under visible light irradiation.

• Visible light active photocatalyst composite, CuWO 4 /GQDs synthesized successfully by a facile approach. • The photocatalytic performance evaluated via degradation of organic pollutant i.e., phenol. • The photocatalytic performance is optimized according to varied weight of main photocatalysts CuWO 4 in composite sample. • GQDs in composite photocatalyst provides an efficient pathway for charge separation. • The performance enhancement is mainly attributed to efficient charge separation. Photocatalysis is one of the most preferred methods for the degradation of organic pollutants as it can lead to complete mineralization of organic pollutants employing sunlight as an energy source. Until so far enormous number of investigations have been done regarding the development of visible light responsive, stable, and cost effective photocatalysts. In the present work, owing to objectives mentioned above, an attempt was made to develop an efficient, cheaper, and visible light active composite photocatalyst consisting of moderate band gap, CuWO 4 with electron conductive graphene quantum dots. A series of photocatalysts was prepared by varying the amount of CuWO 4 while keeping the amount of GQDs fixed, and their activity was evaluated for the phenol degradation under visible light irradiation. The prepared photocatalysts were characterized by using X-ray diffraction (XRD), Scanning electron microscopy (SEM), Raman spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, and Photoluminescence (PL) for the evaluation of crystallinity, functional groups, and properties of charge carrier separation, respectively. The maximum efficiency of photodegradation of phenol simulated wastewater was achieved by sample 0.5GCW (optimized sample having 0.5 wt% of CuWO 4 with respect to fixed amount of GQDs), 53.41%, as compared to the pure CuWO 4 sample, which exhibited 19.08% efficiency. A possible mechanism for enhanced activity of CuWO 4 is proposed mainly due to efficient transfer of electrons from CuWO 4 to graphene quantum dots. The results show that the graphene quantum dots GQDs with the CuWO 4 significantly contributes to the improvement of photocatalytic performance. [ABSTRACT FROM AUTHOR]