Formation of nanoporous NiS films from electrochemically modified GC surface with Nickel Hexacyanoferrate film and its performance for the hydrogen evolution reaction Gopi Kalaiyarasan a,b , Karatha Aswathi c , James Joseph a,b,* a Electrodics and Electrocatalysis Division, CSIR-Central Electrochemical Research Institute, Karaikudi 630003, India b Academy of Scientific and Innovative Research (AcSIR), Chennai 600113, India c School of Chemical Sciences, Kannur University, Payyannur, Kerala 670604, India article info Article history: Received 5 May 2017 Received in revised form 14 July 2017 Accepted 20 July 2017 Available online xxx Keywords: Nickel sulfide Hydrogen evolution reaction Tafel slope Fuel cell Water splitting Porous metal sulfides abstract The production of Hydrogen (H 2 ) gas for fuel cell application using electrochemical methods is attracting the attention of the researchers in recent years owing to its high calorific value. Current researchers are enthused to prepare cost effective catalysts from abundant ele- ments in earth crust for the huge production of H 2 . Recently electrochemical studies are reported based on Metal sulfides and oxides such as MoS 2 , CoS, WO 3 as best catalyst for H 2 generation under diverse pH conditions. We focused on preparing nanoporous Nickel Sul- fide (NiS) films from Nickel Hexacyanoferrate (NiHCF) nanocubes using electrochemical cycling of the precursor films in Sulfide medium and characterized those using spectroscopy and Microscopy techniques such as FT-IR, Raman spectroscopy, XPS, EDS, XRD, FESEM, AFM, and TEM. The cubic structure of NiHCF gets transformed into NiS cubic skeleton by etching in presence of sulfide ions (S 2 ). The nanoporous NiS give best results for Hydrogen Evolution Reaction (HER) in the alkali medium. The catalysts were electrochemically modified on glassy carbon surface for electrochemical characterization including Tafel polarization. For comparison, the same procedure was used to prepare other metal sulfides including MnS, FeS, and CoS to compare their catalytic activity towards Hydrogen evolution. Among them, the NiS was shown to be the most efficient electrocatalyst for hydrogen evolution and has shown promise as an alternative to platinum. © 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved. Introduction In recent years, the renewable, environmentally friendly, cost effective energy source is very important in our daily life. To this point, hydrogen is an alternate source of energy in the field of energy production system due to its high calorific value. It can be produced in many ways such as steam reforming, electrolysis [1], hydrolysis [2], thermal catalysis, thermo- chemical [3], photocatalysis and photo-electrocatalytic methods [4]. Among them, electrocatalytic systems are real- istic in the production of hydrogen by water splitting reaction. * Corresponding author. Electrodics and Electrocatalysis Division, CSIR-Central Electrochemical Research Institute, Karaikudi 630003, India. E-mail address: jameskavalam@yahoo.com (J. Joseph). Available online at www.sciencedirect.com ScienceDirect journal homepage: www.elsevier.com/locate/he international journal of hydrogen energy xxx (2017) 1 e11 http://dx.doi.org/10.1016/j.ijhydene.2017.07.162 0360-3199/© 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved. Please cite this article in press as: Kalaiyarasan G, et al., Formation of nanoporous NiS films from electrochemically modified GC surface with Nickel Hexacyanoferrate film and its performance for the hydrogen evolution reaction, International Journal of Hydrogen Energy (2017), http://dx.doi.org/10.1016/j.ijhydene.2017.07.162