Highly stabilized Ag 2 O-loaded nano TiO 2 for hydrogen production from glycerol: Water mixtures under solar light irradiation Gullapelli Sadanandam a,b,* , Valluri Durga Kumari b,** , Michael S. Scurrell a a Department of Civil and Chemical Engineering, University of South Africa, Florida, 1710, Johannesburg, South Africa b Inorganic and Physical Chemistry Division, Indian Institute of Chemical Technology, Hyderabad, 500 007, India article info Article history: Received 16 July 2016 Received in revised form 16 October 2016 Accepted 22 October 2016 Available online 15 November 2016 Keywords: H 2 production Solar light Glycerol: water mixtures Silver-loaded nano TiO 2 abstract Nano TiO 2 prepared by a hydrothermal method and silver-loaded nano TiO 2 prepared by impregnation were studied for the photocatalytic production of hydrogen from glycerol:- water mixtures. The structural characteristics were revealed using XRD, EDAX, DRS, TEM, XPS, BET surface area and Raman techniques. The photocatalytic hydrogen production has been investigated under solar light irradiation. Effects of nano TiO 2 calcination tempera- ture, silver loading, photocatalyst content, light source and Ag oxidation state on hydrogen production have been systematically studied. Maximum hydrogen production of 200 mmol h 1 g 1 is observed on 4wt% silver-loaded nano TiO 2 catalyst in pure water and the maximum hydrogen production of 7030 mmol h 1 g 1 is observed on 3wt% silver-loaded nano TiO 2 catalyst in glycerol: water mixtures. Silver-loaded nano TiO 2 reduced and pho- todeposited catalysts show similar hydrogen production activities in glycerol: water mix- tures under solar irradiation. The optimum catalyst modified with conducting carbon materials (graphene oxide, graphene, carbon nanotubes) by a solid-state dispersion method were also studied for hydrogen production under solar light irradiation. Compared with pure nano TiO 2 , a 3wt% silver-loaded nano TiO 2 /graphene composite exhibited an approximately 17-fold enhancement of hydrogen production leading to hydrogen pro- duction rates of 12,100 mmol h 1 g 1 . Based on the characterization results and hydrogen production activity on these catalysts, a structureeactivity correlation has been proposed wherein the interacting Ag 2 OeAg phases on the surface of nano TiO 2 play an important role in maintaining a high hydrogen production activity under solar irradiation. © 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved. * Corresponding author. Department of Civil and Chemical Engineering, University of South Africa, Florida, 1710, Johannesburg, South Africa. ** Corresponding author. E-mail addresses: sadaiict@gmail.com, gullas@unisa.ac.za (G. Sadanandam), durgavalluri@rediffmail.com (D.K. Valluri). Available online at www.sciencedirect.com ScienceDirect journal homepage: www.elsevier.com/locate/he international journal of hydrogen energy 42 (2017) 807 e820 http://dx.doi.org/10.1016/j.ijhydene.2016.10.131 0360-3199/© 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.