Base-metal catalysts based on porous layered double hydroxides for alkaline-free sodium borohydride hydrolysis Mehdi Mostajeran a , Vanessa Pr  evot b,** , Sib S. Mal a , Emily Mattiussi a , Boyd R. Davis c , R. Tom Baker a,* a Department of Chemistry and Biomolecular Sciences and Centre for Catalysis Research and Innovation, University of Ottawa, Ottawa, ON K1N 6N5, Canada b Universit e Clermont Auvergne, CNRS, Institut de Chimie de Clermont-Ferrand e ICCF, F-63000 Clermont-Ferrand, France c Kingston Process Metallurgy, 759 Progress Avenue, Kingston, ON K7M 6N6, Canada article info Article history: Received 19 April 2017 Received in revised form 24 May 2017 Accepted 1 June 2017 Available online xxx Keywords: H 2 generation Catalyzed borohydride hydrolysis Supported base-metal catalysts Inverse opal Porous LDH abstract Catalyzed hydrolysis of sodium borohydride (SBH) has demonstrated promise for genera- tion of a pure hydrogen stream for use with fuel cells. In designing an improved continuous hydrogen generator that uses the substantial heat released in the hydrolysis reaction to more effectively separate the sodium borate by-product, we sought a robust base-metal catalyst that could tolerate the exothermic reaction under flow conditions. Working under base-free conditions in ethanol solvent we identified reduced nickel and iron- containing particles supported on layered double hydroxides (LDHs) as robust catalysts. Catalytic activity was enhanced further using high surface area hierarchical supports prepared using the ‘inverse opal’ method. In particular, macroporous NieMgeAl and FeeMgeAl LDHs produced 0.4 and 1.0 mol of hydrogen per minute per mole of active metal of the supported catalyst in aqueous ethanol solvent. © 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved. Introduction Polymer electrolyte membrane (PEM) fuel cells have emerged as one of the most efficient energy generators but their suc- cess in the portable power generation market depends on a convenient source of pure hydrogen fuel [1]. Hydrogen is an environmentally benign and gravimetrically energy-rich fuel that produces only water vapor effluent when combined with air in a PEM fuel cell [2]. The low volumetric energy density of hydrogen, however, requires expensive compression that also hampers its practical applications [3,4]. An alternative approach involves storage of hydrogen in so-called ‘chemical hydrides’ that offer thermal stability, high density and ease of high purity hydrogen release [5]. Although azacycloalkanes could serve as liquid fuels capable of reversible hydrogen storage [6e10], the high temperatures (ca. 200  C), long recharging times and precious metal catalysts required have limited their utility. In contrast, alkali metal borohydrides, MBH 4 , where M is Li [11], Na [12e16], or K [17] have been well * Corresponding author. ** Corresponding author. E-mail address: rbaker@uottawa.ca (R.T. Baker). 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.2017.06.007 0360-3199/© 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved. Please cite this article in press as: Mostajeran M, et al., Base-metal catalysts based on porous layered double hydroxides for alkaline-free sodium borohydride hydrolysis, International Journal of Hydrogen Energy (2017), http://dx.doi.org/10.1016/j.ijhydene.2017.06.007