Cu2O-CuO@biochar composite: synthesis, characterization and its efficient photocatalytic performanceCu2O-CuO@biochar composite: synthesis, characterization and its efficient photocatalytic performance Peer-Reviewed Journal Publication Δημοσίευση σε Περιοδικό με Κριτές 2020-03-312019enThis research focuses on the facile hydrothermal preparation of Cu2O-CuO@biochar (Cu2O-CuO@BC) compo-sites of different BC content (0.5, 1.0, and 2.0 g/L) as efficient photocatalysts for the decomposition and mi-neralization of Reactive Orange 29 (RO29). The textural and morphological properties of biochar-based com-posites were studied utilizing BET, TEM, and SEM analyses. Moreover, EDX, XRD, UV–Vis, DRS and FTIRcharacterization was carried out to evaluate the elemental composition, crystalline structure, optical char-acteristics and functional groups of the samples, respectively. The Cu2O-CuO@BC-1.0 composite with a BCcontent of 1.0 g/L exhibited superior photocatalytic performance than the individual counterparts BC and Cu2O-CuO, due to its narrow band gap and high surface area. These characteristics led to the synergetic ability of UVirradiation and photocatalytic performance of Cu2O-CuO@BC to generate oxidizing species and subsequentradical reactions. The generation of some by-products was verified using GC–MS analysis and accordingly, apossible pathway was proposed. 94.12% degradation efficiency of RO29 was obtained by Cu2O-CuO@BC-1.0composite at the natural pH of RO29 solution (8.9) and initial RO29 concentration of 20 mg/L after 90 min ofphotocatalysis. Under identical conditions, 47.31% and 79.62% COD removal efficiencies were observed after 90and 180 min treatment, respectively.http://creativecommons.org/licenses/by/4.0/Applied Surface Science498December 2019 Khataee, Alireza Kalderis Dimitrios Καλδερης Δημητριος Gholami Peyman Fazli Arezoo Moschogiannaki Marilena Binas Vasileios Lykaki Maria Λυκακη Μαρια Konsolakis Michail Κονσολακης Μιχαηλ Elsevier Copper oxide composite Photocatalyst Hydrothermal synthesis Advanced water treatment Biochar