Effect of nanocomposite partnering of g-C3N4 with Morinda pubescens leaf extract mediated Sr doped Ni/NiO on the photocatalytic dye detoxification: Confirmation by seed germination test

A carbonaceous 2D material g-C3N4 was added as the composite partner to Sr doped (Ni/NiO) to synthesize a green routed nanocomposite (Ni/NiO):Sr/g-C3N4 using the leaf extract of Morinda pubescens. The synthesized material was employed as a photocatalyst towards complete detoxification of synthetic toxic dyes methylene blue (MB-cationic) and rose bengal (RB- anionic) widely used in textile, leather and paper industries. The efficiency of the nanocomposite was compared with those of Ni/NiO and Ni/NiO:Sr samples. The composite formation was verified through XRD, SEM, TEM, EDAX, FTIR, UV–Vis-NIR and XPS analyses. The Sr doped (Ni/NiO)/g-C3N4 nanocomposite showed significant higher photocatalytic efficiency of 98 % for MB dye and 94 % for RB dye compared to (Ni/NiO):Sr (72 and 65 %) and (Ni/NiO) (83 % and 70 %) within 45 min of irradiation. The inclusion of g-C3N4 in the nanocomposite reduces the band gap (from 3.9 eV for Ni/NiO to 2.9 eV for (Ni/NiO):Sr/g-C3N4), enabling it to serve as visible light responsive photocatalyst. The stability of the material was confirmed by conducting re-cycle test. To find the role of active species involved in the photocatalysis, trapping test was conducted, the result of which showed that OH⁎ radicals predominate over the other three species (e−, h+ and O2−) in degrading the dye molecules. The attainment of complete detoxification of the test dye solutions was demonstrated by conducting seed germination test using Amaranthus viridis seeds. A superior seed germination was observed in the case of water sample treated by (Ni/NiO):Sr/g-C3N4 nanocomposite compared to all the other samples including the control. Thus, this eco-friendly nanocomposite synthesized using Morinda pubescens plant leaf extract shows its potential for efficient detoxification of organic dyes through photocatalytic process. [Display omitted] •(Ni/NiO):Sr/g-C3N4 nanocomposite was synthesized via green route for the first time.•Nanocomposite exhibits significant photocatalytic efficiency of 98 % against MB dye.•Photocatalytically treated water leads to better seed germination than ordinary water.