The gravimetric hydrogen storage efficiency of silicon has been widely reported as 14 wt.%, suggesting that this material should be an excellent hydrogen generation source for portable applications. However, in the case of the reaction of silicon powder with 20 wt.% sodium hydroxide solution at 50 °C, the observed production of hydrogen fails to realize these high expectations unless a large excess of basic solution is used during the reaction, rendering the use of silicon in such systems uncompetitive compared with chemical hydride based technologies. By investigating the molar ratio of water:silicon from a large excess of water towards the stoichiometric 2:1 ratio dictated by the reaction equation, this study shows that for the reaction of silicon in 20 wt.% sodium hydroxide solution, the quantity of hydrogen produced decreases as the 2:1 ratio expected from the equation for the reaction is approached. Furthermore, in order to reach 80% of the theoretical efficacy, a molar ratio of 20:1, or 12 mL of 20 wt.% sodium hydroxide solution per gram of silicon, would be required. These results suggest that the actual gravimetric hydrogen storage capacity is less than 1%, casting doubts as to whether the use of silicon for hydrogen generation in real systems would be possible. © 2016 The Authors. International Journal of Energy Research published by John Wiley & Sons Ltd.

The formation of different nickel and cobalt layered hydroxide phases by a variety of solution and solid-state synthesis methods have been investigated. Initially, the preparative conditions were refined to generate single-phase products from metal(II) nitrate hexahydrate starting materials and were characterised by powder X-ray diffraction, vibrational spectroscopy and thermogravimetric analysis. As well as the brucite type β-M(OH)2 and the hydrotalcite-like [M(OH)_2-x(H₂O)_x]^x+ alpha-phases (where M = Ni, Co), two different hydroxynitrate phases were isolated with the generic formula M(OH)_2-x(NO₃)_x with x = 0.67 and 1.0 (where M = Ni, Co). The reduction of symmetry of the nitrate anion from D_3h to C_2v allows the alpha-phases to be distinguished from the two different layered hydroxynitrate phases by both infrared and Raman spectroscopy through the loss of symmetry and concomitant splitting of the degenerate bands. The symmetric N-O stretch enables the two hydroxynitrate phases to be distinguished from one another through the sharp absorption bands at ca. 1000 cm^-1 (x = 0.67) and ca. 1050 cm^-1 (x = 1.0). The thermogravimetric analysis data of the phases showed key differences between the layered hydroxides, with anhydrous phases having singular weight losses over short temperature ranges and hydrated phases having multiple losses over more extended temperature ranges.

Experimental techniques including DRIFTS and solid-state NMR spectroscopy are employed alongside ab initio molecular dynamics simulations to characterise the mechanism of adsorption of n-butanol by ZIF-8; revealed to be driven by hydrogen bonding.

There is a growing research interest in the development of portable systems which can deliver hydrogen on-demand to proton exchange membrane (PEM) hydrogen fuel cells. Researchers seeking to develop such systems require a method of measuring the generated hydrogen. Herein, we describe a simple, low-cost, and robust method to measure the hydrogen generated from the reaction of solids with aqueous solutions. The reactions are conducted in a conventional one-necked round-bottomed flask placed in a temperature controlled water bath. The hydrogen generated from the reaction in the flask is channeled through tubing into a water-filled inverted measuring cylinder. The water displaced from the measuring cylinder by the incoming gas is diverted into a beaker on a balance. The balance is connected to a computer, and the change in the mass reading of the balance over time is recorded using data collection and spreadsheet software programs. The data can then be approximately corrected for water vapor using the method described herein, and parameters such as the total hydrogen yield, the hydrogen generation rate, and the induction period can also be deduced. The size of the measuring cylinder and the resolution of the balance can be changed to adapt the setup to different hydrogen volumes and flow rates.