Green synthesized carbon quantum dots as TiO 2 sensitizers for photocatalytic hydrogen evolution Idris Sargin a,* , Gizem Yanalak a , Gulsin Arslan a , Imren Hatay Patir b a Selcuk University, Faculty of Science, Department of Biochemistry, Konya, Turkey b Selcuk University, Faculty of Science, Department of Biotechnology, Konya, Turkey highlights graphical abstract Carbon quantum dots (CQDs) were prepared from edible mushroom Agaricus bisporus. A facile and green route was fol- lowed in production of CQDs. CQD characterization by XRD, FTIR, XPS, TEM, UV-vis and fluo- rescence spectra analysis. CQDs were used as a sensitizer for TiO 2 in photocatalytic production of hydrogen. Photocatalytic H 2 evolution by TiO 2 /CQD and TiO 2 /CQD/Pt was 2129 and 14143 mmol g 1 . article info Article history: Received 18 April 2019 Received in revised form 31 May 2019 Accepted 25 June 2019 Available online xxx Keywords: Carbon quantum dot Hydrogen evolution Edible mushroom Green synthesis abstract Carbon quantum dots (CQDs) have attracted growing interest due to their superior lumi- nescent properties, which make them excellent photosensitizers for TiO 2 . This study presents the green-synthesis of CQDs from edible mushroom Agaricus bisporus through microwave irradiation. In the study as-synthesized CQDs were used as a sensitizer for TiO 2 in photocatalytic hydrogen evolution in aqueous triethanolamine (sacrificial reagent) under visible-light irradiation. Photocatalytic hydrogen production activity of CQD- sensitized TiO 2 was found to be 472 mmol g 1 h 1 (without loading any noble metal co- catalyst) and 1458 mmol g 1 h 1 (with loading Pt co-catalyst). The study revealed that the CQDs from mushroom A. bisporus can be used as an efficient sensitizer for TiO 2 in pho- tocatalytic hydrogen production. © 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved. * Corresponding author. Department of Biochemistry, Faculty of Science, Selcuk University, Konya, Turkey. E-mail address: idris.sargin@selcuk.edu.tr (I. Sargin). Available online at www.sciencedirect.com ScienceDirect journal homepage: www.elsevier.com/locate/he international journal of hydrogen energy xxx (xxxx) xxx https://doi.org/10.1016/j.ijhydene.2019.06.168 0360-3199/© 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved. Please cite this article as: Sargin I et al., Green synthesized carbon quantum dots as TiO 2 sensitizers for photocatalytic hydrogen evolution, International Journal of Hydrogen Energy, https://doi.org/10.1016/j.ijhydene.2019.06.168