International Journal of Hydrogen Energy 31 (2006) 891 – 898 www.elsevier.com/locate/ijhydene Alternate synthetic strategy for the preparation of CdS nanoparticles and its exploitation for water splitting M. Sathish, B. Viswanathan, R.P. Viswanath ∗ Department of Chemistry, Indian Institute of Technology Madras, Chennai-600 036, India Available online 12 September 2005 Abstract Cadmium sulphide nanoparticles (6–12 nm) are prepared by a precipitation process using different zeolite matrices as templates. The nanoparticles were characterized by UV-Vis, XRD, SEM, TEM and sorptometric techniques. XRD study shows the presence of hexagonal and cubic phases for the nanoparticles whereas in case of the bulk samples only the hexagonal phase is observed. These nanomaterials have been used as catalysts for the photocatalytic decomposition of water. The nanoparticles show a higher hydrogen evolution rate compared to the bulk samples which correlates well with the particle size and surface area. Noble metal (Pt, Pd, Rh, Ru)-loaded samples were subsequently prepared and tested for hydrogen evolution reaction. The presence of Pt metal is found to enhance the hydrogen production rate whereas the hydrogen production rate is retarded in the presence of Ru metal. This has been explained on the basis of metal hydrogen bond, redox potential and work function of the noble metal.  2005 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved. Keywords: Photocatalyst; Hydrogen production; CdS nanoparticles; Water splitting; Zeolite template 1. Introduction Production of hydrogen from an inexhaustible source, wa- ter, by a cheaper route has been under extensive investiga- tions in recent years [1,2]. Among different processes used for hydrogen production, photocatalysis is a method which has to be improved in terms of viability where sunlight can be utilized as a sustainable energy source for hydrogen pro- duction. Selection of a suitable photocatalyst is an impor- tant criterion to establish the process as workable for the maximum quantity of hydrogen production. Essentially, the photocatalyst should have appropriate conduction and va- lence band edge positions in order to reduce and oxidize the H + and OH - ions, respectively. For better hydrogen ∗ Corresponding author. Tel.: +91 44 22574216; fax: +91 44 22574202. E-mail address: rpv@iitm.ac.in (R.P. Viswanath). 0360-3199/$30.00  2005 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.ijhydene.2005.08.002 evolution activity, the bottom of the conduction band should have more negative potential than the H + /H 2 redox poten- tial. The values of the top edge of the valence band should be more positive with the oxidation potential of water. In addition to these criteria, the photocatalyst should absorb light especially in the visible region and should have good photo-stability under the irradiation conditions. Several types of semiconducting materials such as TiO 2 , CdS, ZnO and Fe 2 O 3 have been investigated for hydrogen production [3–5]. Among them CdS shows light absorption in the visible region and has suitable conduction band po- tential to reduce the H + ion effectively. However, the utility of CdS as a photocatalyst has been limited due to its anodic decomposition, the so-called photocorrosion. A number of attempts have been made to overcome this disadvantage by using suitable sacrificial agents. In general, an Na 2 S and Na 2 SO 3 mixture has been widely used as a sacrificial agent [6]. Coupling of CdS with other semiconductors like TiO 2 and ZnS has also been studied [7]. It has been observed