Novel Synthesis of Graphene Supported Nickel Borides from Metal Organic Framework Precursors

Abstract

As the worlds supply of fossil fuels dwindles, more and more research is being conducted to find a reliable alternative energy source. One promising source of energy is hydrogen, which is not only the most abundant element in the universe, but when burned as a fuel source produces only water as a biproduct. The main issue preventing hydrogen from being utilized as a fuel source is the storage. Hydrogen primarily exists as a gas and must be stored in compressed tanks. These tanks run the risk of explosions, so work is being done to produce hydrogen gas over time with a hydrogen feedstock material (HFM). Sodium borohydride (NaBH4) is an HFM that contains 10.8% hydrogen by weight and readily reacts with water to produce hydrogen gas.1 This reaction occurs slowly and needs a catalyst to make its hydrogen production viable. In the past, work has been done with precious metal catalysts and metal catalyst support on carbon materials.2,3 The goal of this study was to explore a novel method of synthesizing nickel borides supported on graphene (NiB@G). NiB@G was formed by the reduction of a metal organic framework precursor (NiMOF-5@GO) at room temperature (RT 295K). Both NiMOF-5@GO and NiB@G were characterized using Powder X-Ray Diffraction (PXRD), Scanning Electron Mircroscopy (SEM, Figure 1), Energy Dispersive X-Ray Spectroscopy (EDS), Transmission Electron Microscopy (TEM), and Fourier Transform Infrared Spectroscopy (FTIR). NiB@G was additionally characterized with Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) and tested for its catalytic ability at temperatures of 283K-303K. This product showed an excellent activation energy of 49 kJ mol-1 compared to previous work with nickel, cobalt, and raney-nickel catalysts.4 This product also showed good stability, performing well after multiple uses of the same catalyst. A novel method of producing an efficient catalyst for the hydrolysis of sodium borohydride will help scientists move forward in the mass production of hydrogen fuel.Works Cited: Schlesingehr H.I.; Brown, H.C.; Finholt A.E.; Gilbreath J.R.; Hoekstra H.R.; Hyde E.L.; Sodium Borohydride, Its Hydolysis and its Use as a Reducing Agent in the Generation of Hydrogen; Chem. Soc., (1953), 75 (1), pp 215–219Clay Huff, Julia M. Long, Austin Heyman, and Tarek M. Abdel-Fattah Palladium Nanoparticle Multiwalled Carbon Nanotube Composite as Catalyst for Hydrogen Production by the Hydrolysis of Sodium BorohydrideACS Applied Energy Materials 2018 1 (9), 4635-4640 DOI: 10.1021/acsaem.8b00748Huff, C., Long, J. M., Aboulatta, A., Heyman, A., & Abdel-Fattah, T. M. Silver Nanoparticle/Multi-Walled Carbon Nanotube Composite as Catalyst for Hydrogen Production. ECS Journal of Solid State Science and Technology (2017) 6(10), M115–M118. doi:10.1149/2.0051710jssKaufman, C. M., & Sen, B. (). Hydrogen generation by hydrolysis of sodium tetrahydroborate: effects of acids and transition metals and their salts. Journal of the Chemical Society, Dalton Transactions, 1985 (2), 307. doi:10.1039/dt9850000307 Figure 1: SEM images at 50 microns of the graphene support for the nickel borides. The clear presence of graphene like sheets is seen in the image with conglomerates of sheets have dimensions of much larger than 50 microns Figure 1