Facile synthesis of well dispersed Pd nanoparticles on reduced graphene oxide for electrocatalytic oxidation of formic acid Rahul Krishna a,b,* , Diana M. Fernandes c , Adriana Marinoiu d , Jo ~ ao Ventura e , Cristina Freire c , Elby Titus b a I3N Department of Physics, University of Aveiro, 3810-193, Aveiro, Portugal b Center for Mechanical Technology and Automation (TEMA), Department of Mechanical Engineering, University of Aveiro, Portugal c REQUIMTE/LAQV, Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, 4169-007, Porto, Portugal d National R&D Institute for Cryogenics and Isotopic Technologies, ICIT Rm. Valcea, National Centre for Hydrogen and Fuel Cell, Romania e IFIMUP and IN e Institute of Nanoscience and Nanotechnology, and Department of Physics and Astronomy, Faculty of Sciences, University of Porto, 4169-007, Porto, Portugal article info Article history: Received 31 December 2016 Received in revised form 25 April 2017 Accepted 27 April 2017 Available online xxx Keywords: Pd nanoparticles Reduced graphene oxide Formic acid Hydrogen energy abstract In present study, we report a facile synthesis of crystalline, small size Pd nanoparticles (NPs) on reduced graphene oxide (RGO) abbreviated as Pd/RGO for electrocatalytic oxida- tion of formic acid (FA). Here, first graphene oxide (GO) was reduced by the green method using L-ascorbic acid and citric acid and further Pd NPs were decorated on RGO by a facile method without using any reducing agents. The reduction of GO to RGO and synthesis of Pd NPs was confirmed by the X-ray diffraction (XRD) and X-ray photoelectrons (XPS) tech- niques. Surface morphology of Pd/RGO nanocomposite was evaluated by the scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. The electrocatalytic behavior of Pd/RGO nanocomposite was tested by using of cyclic voltam- metric (CV) technique for electro-oxidation of FA in mixed solution of 0.5 M HCOOH þ 0.5 H 2 SO 4 at RT. Results shows that the higher electrocatalytic activity of Pd/RGO nano- composite compare to Pd NPs. © 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved. Introduction Recently, vast research is going on to develop alternatives to fossil fuels due to continuous depletion of proven petroleum reservoirs and concerning environmental threats based on greenhouse gas emissions [1e4]. In such contest, presently research is focused on clean energy solutions [5]. Hydrogen (H 2 ) is consider as choice of fuel for power generation due to its high energy density and clean combustion without emission of any harmful chemical by-products [6]. However, conven- tional storage technologies such as high pressure storage * Corresponding author. I3N Department of Physics, University of Aveiro, 3810-193, Aveiro, Portugal. Fax: þ351 234370953. E-mail address: rahulkrishna@ua.pt (R. Krishna). Available online at www.sciencedirect.com ScienceDirect journal homepage: www.elsevier.com/locate/he international journal of hydrogen energy xxx (2017) 1 e8 http://dx.doi.org/10.1016/j.ijhydene.2017.04.263 0360-3199/© 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved. Please cite this article in press as: Krishna R, et al., Facile synthesis of well dispersed Pd nanoparticles on reduced graphene oxide for electrocatalytic oxidation of formic acid, International Journal of Hydrogen Energy (2017), http://dx.doi.org/10.1016/ j.ijhydene.2017.04.263