Synthesis and characterisation of neodymium doped- zinc oxide–graphene oxide nanocomposite as a highly efficient photocatalyst for enhanced degradation of indigo carmine in water under simulated solar light Samuel O. B. Oppong 1 • William W. Anku 1 • Sudheesh K. Shukla 1 • Penny P. Govender 1 Received: 25 April 2016 / Accepted: 2 July 2016 Ó Springer Science+Business Media Dordrecht 2016 Abstract A nanocomposite (Nd–ZnO–GO) with enhanced photocatalytic proper- ties was synthesized by co-precipitation method. The structures, morphologies and photocatalytic activities of the nanocomposite were studied using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spec- troscopy, and ultraviolet–visible spectroscopy. Indigo carmine (IC) dye was used to evaluate the photocatalytic performance of the nanocomposite under simulated solar light. The photocatalytic results indicate that the nanocomposite [Nd–ZnO–GO (0.3 % Nd)] showed good photocatalytic activity and could be considered as a promising photocatalyst for treatment of organic pollutant in water. The high and efficient photocatalytic degradation of IC solution by the nanocomposite [Nd–ZnO– GO (0.3 % Nd)] is attributed to improve absorbance in the visible region and the separation of charge carriers due the combined effect of Nd and GO. Analysis from Total organic carbon (TOC) displayed a higher degree of complete mineralisation of IC (TOC removal of 76 %) which decreases the formation of possible toxic degradation by-products. The stability of Nd–ZnO–GO (0.3 % Nd) nanocomposite caused it to be reused for five times reaching 83.0 % degradation efficiency after the five cycles. Keywords Graphene oxide Á Neodymium Á ZnO Á Indigo carmine Á Co-precipitation & Samuel O. B. Oppong samkello2002@yahoo.com & Penny P. Govender pennyg@uj.ac.za 1 Department of Applied Chemistry, University of Johannesburg, P.O. Box 17011, Doornfontein Campus, Johannesburg 2028, South Africa 123 Res Chem Intermed DOI 10.1007/s11164-016-2636-2