CHEMICAL ENGINEERING TRANSACTIONS VOL. 41, 2014 A publication of The Italian Association of Chemical Engineering www.aidic.it/cet Guest Editors: Simonetta Palmas, Michele Mascia, Annalisa Vacca Copyright © 2014, AIDIC Servizi S.r.l., I SBN 978-88-95608-32-7; I SSN 2283-9216 MoS2 Nanosheets for HER and LIB Maria Sarno, Anna Garamella, Claudia Cirillo*, Paolo Ciambelli Department of Industrial Engineering and Centre NANO_MATES, University of Salerno Via Giovanni Paolo II ,132 - 84084 Fisciano (SA), Italy clcirillo@unisa.it Very high surface area thin nanosheets of MoS 2 , with also low lateral dimension, as well as high number of edges sites, were prepared via a solvent free, easily controllable and scalable process. The syntheses were performed by thermolysis of ammonium thiomolybdates (NH 4 ) 2 MoS 4 in a continuous flow reactor, monitored with a mass spectrometer. The precursor decomposition was promoted in the temperature range 25-400°C, obtaining amorphous MoS2. Nanosheets were obtained thought a successive annealing, while material order can be improved by progressively increasing temperature and time. It was found that the annealing time at the end of the first step determines a reduction of the final nanosheets lateral size and number of layers. The samples were characterized by Raman Spectroscopy, Scanning (SEM) and Transmission (TEM-EDS) Electron Microscopy, thermogravimetric analysis (TG-DTG-MS), X-ray diffraction (XRD). 1. Introduction MoS 2 nanostructure have generated intense scientific interest owing to their promising electronic and mechanical properties (Ramakrishna Matte et al., 2010), in the area of energy conversion and storage. MoS 2 has been widely investigated as catalysts for electrocatalytic or photocatalytic hydrogen evolution reaction (HER) in aqueous solution and as efficient electrode material for lithium ion batteries (LIBs) (Zhao et al., 2013; Stephenson et al., 2014). Even if bulk MoS 2 is not active for the HER, it has been forecasted by using density functional theory calculation (Hinnemann et al., 2005) an excellent electrocatalytic activity (tafel slope 55–60 mVdec −1 ), linearly dependent by the number of edge sites, for MoS 2 nanocatalyst (Jaramillo et al., 2007) prepared on an Au substrate. The same authors (Bonde et al., 2008) prepared later a more commercially relevant nanocatalyst, MoS 2 nanoparticles on a Toray carbon paper, finding higher tafel slope (120 mV/dec) and exchange current density. Further information about the electrocatalytic activity of MoS 2 comes form the paper of Merki et al. (Merki et al., 2011). They prepared amorphous thin films of MoS x (about 1-2 μm thick), finding that the real catalyst was amorphous MoS 2 , that exhibits a Tafel slope of 40 mVdec −1 . More recently, engineering the MoS2 structure, to have an high surface area mesostructure, exposing a large fraction of edge sites, a tafel slope of 50 mV/dec, has been found (Kibsgaard et al., 2012). The reported results clearly demonstrate that the catalytic activity of MoS 2 toward the HER is very promising and closely associated with the different morphology of the prepared nanostructures. It deserves to be further investigated to definitely elucidate the effect of the support through a systematic comparison of the same nanostructured MoS 2 on a support and alone, and clarified the effect of order of the nanostructured materials prepared through a simple and scalable process. MoS 2 is a conductive material characterized by a distinctive layered structure that makes it favorable for reversible Li+ intercalation/deintercalation (Xiao et al. 2010). The electrochemical performance of MoS 2 as a LIB electrode was believed to be significantly influenced by morphology, structure and particle size. The Li diffusion path could be significantly shortened in nanostructured MoS 2 improving the performance. As a nanostructure materials MoS 2 can exist in a diverse range of morphologies and microstructures. These include fullerene like MoS 2 , MoS 2 nanotubes, MoS 2 nanowires, nanoribbons and nanosheets. In particular, with regards to this specific application, hydrothermal synthesized MoS 2 nanoflakes (Feng et al., 2009) and amorphous MoS 2 nanoflowers (Li et al., 2009) (prepared by an hydrothermal method), and nanotubes (Dominko et al., 2002) (prepared by a mixture of C60, used as promoter, and MoS 2 powder at 1010 K and DOI: 10.3303/CET1441066 Please cite this article as: Sarno M., Garamella A., Cirillo C., Ciambelli P., 2014, Mos2 nanosheets for her and lib, Chemical Engineering Transactions, 41, 391-396 DOI: 10.3303/CET1441066 391