RESEARCH PAPER A ternary Z-scheme WO 3 –Pt–CdS composite for improved visible-light photocatalytic H 2 production activity Maxwell Selase Akple & Sajan Ponnappa Chimmikuttanda Received: 13 March 2018 /Accepted: 24 August 2018 # Springer Nature B.V. 2018 Abstract Fabrication of advanced semiconductor system for photocatalytic water splitting into valu- able hydrogen energy has attracted a lot of attention worldwide due to the increasing global energy crises. In this work, a ternary WO 3 –Pt–CdS composite was synthesized through coprecipitation and hydrother- mal reactions. The ternary composite (i.e. WO 3 –Pt– CdS) showed a high hydrogen evolution rate of 390 μ mol h - 1 g - 1 exceeding CdS alone (27 μmol h -1 g -1 ), WO 3 –CdS (55 μmol h -1 g -1 ), and CdS–Pt (135 μmol h -1 g -1 ). The enhanced pho- tocatalytic activity is mainly attributed to the forma- tion of Z-scheme heterojunction between WO 3 and CdS, which results in the effective space charge sep- aration. Meanwhile, the Pt in the as-prepared WO 3 – Pt–CdS plays an essential role as a bridge for accel- erating the charge transportation between WO 3 and CdS. This work provides another effective way of developing visible-light-driven photocatalysts for practical application. Keywords Composite . Hydrogen production . Visible light . Z-scheme . Nanostructured catalysts . Energy conversion Introduction The conversion of solar energy into valuable chemical fuels is an attractive and sustainable strategy for solving the global energy and environmental problems (Bu et al. 2015; Cao et al. 2015; Hu et al. 2018; Tan et al. 2015). Since Fujishima and Honda breakthrough reported water splitting using a TiO 2 electrode under light irradiation, photocatalytic water splitting using solar energy has re- ceived pronounced attention as one key solution for converting solar energy into chemical energy in the form of clean and renewable hydrogen fuel (Cui et al. 2014; Li et al. 2015; Wang et al. 2014). To date, many semicon- ductor photocatalysts for hydrogen evolution have been developed such as TiO 2 ,Cu 2 O, CdS, ZnO, ZnS, WO 3 and BiVO 4 (Cao et al. 2015; Yu et al. 2014a; Yu et al. 2012). Nevertheless, most of these photocatalysts cannot give high hydrogen production efficiency because of the facile electron–hole pairs’ recombination and low light utiliza- tion (Liu et al. 2014a). In order to overcome these limita- tions, many strategies have been developed to improve the performance including doping, morphology tuning, semiconductor coupling and heterostructure formation (Asahi et al. 2001; Cui et al. 2014; Tada et al. 2006; Tanaka et al. 2014). Among these strategies, construction of composite heterostructure (or heterojunction type II) J Nanopart Res (2018) 20:231 https://doi.org/10.1007/s11051-018-4341-0 M. S. Akple (*) Department of Mechanical Engineering, Ho Technical University, P.O. Box HP 217 Ho, Volta Region, Ghana e-mail: makple@htu.edu.gh S. P. Chimmikuttanda R and D, Chemistry, VerdeEn Chemicals Pvt. Ltd., D-11, UPSIDC Industrial Area, Gulawati Road, Hapur District, Mussoorie, Uttar Pradesh 201015, India e-mail: sajan.saj@rediff.com