Visible light-driven photocatalytic degradation of rhodamine B and industrial dyes (texbrite BAC-L and texbrite NFW-L) by ZnO-graphene-TiO2 composite

• The ZGT ternary nanocomposite catalyst was successfully synthesized.
• The ZGT catalyst exhibited excellent photocatalytic activity under visible-light.
• The synthesized ZGT can be used as a highly effective catalyst for dye wastewaters.
• The prepared ZGT catalyst exhibited a highly stability and recyclability.
• The ZGT can be a suitable candidate for eco-friendly environmental applications.

Visible light-responsive ZnO-graphene-TiO2 (ZGT) composite catalyst was successfully synthesized via a simple solvothermal process. The intrinsic characteristics of as-obtained samples were examined using a variety of techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDS). The band gap energies of the samples were evaluated by UV–vis diffuse reflectance spectroscopy (UV-vis DRS). The photocatalytic activities of as-obtained catalysts were assessed based on the degradation of rhodamine B (RhB), texbrite BAC-L (TBAC) and texbrite NFW-L (TNFW) under visible-light irradiation. ZGT exhibited higher visible-light-activated photocatalytic activity than did other samples (ZGT (7.97 × 10−4 min−1) > ZG (3.43 × 10−4 min−1) > graphene (2.43 × 10−4 min−1) > TiO2 (2.22 × 10−4 min−1) > ZnO (1.87 × 10−4 min−1)). In addition, ZGT showed higher enhanced photocatalytic degradation of RhB than did other dyes (RhB (7.97 × 10−4 min−1) > TNFW (5.20 × 10−4 min−1) > TBAC (2.48 × 10−4 min−1)). It is therefore evident that the synthesized ZGT can be used as a high performance catalyst for dye wastewaters. Moreover, the detailed photocatalytic mechanism of the photodegradation process is discussed.

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