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Available online xxxKeywords: Hydrogen fuel cell Silicon Siliconewater reaction Ball milling a b s t r a c t The development of a safe technique for the supply of hydrogen to small portable fuel cells has emerged as a significant barrier to their deployment in recent years, with solutions centering on the use of hydrogen absorption materials, or the generation of hydrogen through chemical reaction. In the present work we demonstrate that the ball-milling of Si under inert conditions in the presence of KOH and sucrose results in the formation of a fineSi-based powder which reacts spontaneously with water at ambient starting temperature to evolve hydrogen rapidly at high yield. Embedded KOH is capable of accelerating the hydrolysis reaction of silicon by the self-heating effect attributed to dissolution heat of KOH, obviating the need for external heating to initiate the reaction; it also reduces the sensitivity of the reaction to oxide contamination of the Si surface by enabling its dissolution in the form of soluble silicates. Moreover, the siliconewater reaction can be switched on and off by adjusting the ambient temperature. It is shown that ball-milled, KOH-embedded Si powder is able to react with different water sources, such as tap water, river water, and salt water, to produce H 2 under aerobic conditions. The method represents a cheap scalable approach for the safe provision of hydrogen fuel to small fuel cells.

Conductive, boron doped diamond (BDD) is an extraordinary material with many applications in electrochemistry due to its wide potential window, outstanding robustness, low capacitance and resistance to fouling. However, in photoelectrochemistry, BDD usually requires UV light for excitation, which impedes e. g., usage in CO2 to fuel reduction. In this work, a heavily boron doped, nanostructured diamond electrode with enhanced light absorption has been developed. It is manufactured from BDD by reactive ion etching and presents a coral‐like structure with pore diameters in the nanometer range, ensuring a huge surface area. The strong light absorbance of this material is clearly visible from its black color. Consequently, the material is called Diamond Black (DB). Electrochemical and X‐ray photoelectron spectroscopy measurements performed at near‐ambient pressure conditions of water vapor demonstrate increased surface reactivity for the hydrogen‐terminated DB compared to oxidized surfaces. Depending on the surface termination, the wettability and hence the electrochemically accessible area can be changed. Photoelectrochemical conversion of CO2 was demonstrated using a Cu2O‐modified electrode in ionic liquids under solar illumination. High formic acid production rates at low catalyst deposition times can be obtained paired with an increased catalyst stability on the DB surface.

Methods for chemical surface functionalization for carbon black (CB) nanoparticles were studied to produce (CB)/polypropylene (PP) nanocomposites with superior electrical and thermal properties. Nanoparticle dispersion is known to directly control the extent to which nanocomposites maximize the unique attributes of their nanoscale fillers. As a result, tailored nanoparticle surface chemistry is a widely utilized method to enhance the interfacial interactions between nanoparticles and polymer matrices, assisting improved filler dispersion. In this work, a rapid chemical functionalization approach using a number of diarylcarbene derivatives, followed by the azo-coupling of substituted diazonium salts, for the covalent introduction of selected functional groups to the CB surface, is reported. Characterization of the modified CB by XPS, TGA, CHN, and ATR-IR collectively confirmed surface functionalization, estimating surface grafting densities of the order of 10(13) and 10(14) molecules/cm(2). Nanocomposites, synthesized by solvent mixing PP with pristine and modified CB, demonstrated macroscopic property changes as a result of the nanoparticle surface functionalization. Pronounced improvements were observed for PP nanocomposites prepared with a dodecyl-terminated diaryl functionalized CB, in which TEM analysis established improved nanofiller dispersion owing to the enhanced CB-PP interfacial interactions in the nanocomposite. Observed dielectric relaxation responses at 20 wt % loading and a reduced percolation threshold realized conductivities of 1.19 × 10(-4) S cm(-1) at 10 wt %, compared to 2.62 × 10(-15) S cm(-1) for pristine CB/PP nanocomposites at the same filler loading. In addition, thermal properties signify an increase in the number of nucleation sites by the raised degree of crystallinity as well as increased melting and crystallization temperatures.

The manipulation of electron transfer reactions at surfaces forms the cornerstone of electrodeposition and processing of materials on substrates with precise control of stoichiometry and oxidation state. However, the utility of this technique, which is mainly carried out in liquid electrolytes, is ultimately limited by the electrolysis of the solvent which limits a potential window to at best 4.8 V in nonaqueous solutions (A. J. Bard and L. R. Faulkner, Electrochemical Methods: Fundamentals and Applications, Wiley, New York, NY, 2nd edn, 2001; ref. 1) and can be up to 6 V in ionic liquids (A. P. Abbott, K. J. McKenzie, Phys. Chem. Chem. Phys., 2006, 8, 4265-4279; ref. 2). A long-sought-after goal has been to develop a corresponding technique at the solid/gas interface in the absence of a solvent which will allow in principle a potential window in excess of 100 V (J. M. Goodings, J. Guo, A. N. Hayhurst and S. G. Taylor, Int. J. Mass Spectrom., 2001, 206, 137-151; ref. 3). This extended potential window will enable chemistry at the solid/gas interface that is not possible at the solid/liquid interface. Here we describe a new approach to gas-phase electrochemistry using a flame plasma as the electrolyte medium. We demonstrate the controlled electrochemical reduction of Cu(+) to Cu(0) at an electrode surface in a flame environment with resulting deposition of either Cu(2)O or Cu species on conducting diamond electrodes. This approach is novel in that it involves the application of an electrochemical potential difference to change the redox state of surface confined species, not the measurement of flame bore ions (as in flame ionisation detectors). This new technique will permit deposition of films and particles on surfaces with control over the oxidation state of the species. This will provide a valuable enhancement to the capabilities of materials preparation methods such as flame spray deposition.

Although carbon black nanoparticles (CBs) at ca. 10 wt.% are widely used as a conductive additives for energy storage electrodes for lithium ion batteries and supercapacitors, they are not extensively used as the active materials for such devices due to their poor ionic conductivity and wettability. In this work, CBs were oxidized by a process of refluxing with conc. HNO3 for 6-72 h, providing oxidized CBs (OCBs) with different oxygen-containing groups (i.e., carboxyl, hydroxyl, and carbonyl) and contents. The OCBs refluxed for 12 h have ca. 2.0-fold higher accessible active surface area than that of the pristine CBs. The as-fabricated symmetric supercapacitor using OCBs refluxed for 12 h with a [BMP][DCA] ionic liquid electrolyte exhibits specific energy and maximum specific power of 88 Wh kg-1 and 8429 W kg-1 , respectively with the capacitance retention over 97% after 6000 cycles. A single coin-cell supercapacitor prototype fully charged can supply electrical power to a red LED over 24 min. This device may be practically used as a battery replacement in high power applications.

Premixed hydrogen/oxygen flame doped with ionisable alkali metals was considered as a dilute electrolyte. Two identical premixed flames which were in physical contact, served as a two compartment flame electrolyte cell. Five different electrochemical cells were studied, each containing a different combination of three alkali metals, Li, K and Cs. Pairs of boron doped diamond (BDD) and platinum electrodes were used to measure the overall zero current cell potential. The total potential measured across the cell was shown to be the sum of the mixed potential, dependent on the identity of ionised species present in the flame, and the diffusion potential originating at the junction between the two flames. Classical kinetic molecular theory and electrochemical theory of mixed potentials have been applied to account for the potential difference measured across these gas phase electrochemical cells. The relative merits of both models are discussed in the context of the experimental results obtained.

This report describes the development of a high temperature reference electrode material for gas phase electrochemistry investigations. The electrode is constructed by careful assessment of different metal/metal oxide materials and operational stability in flame electrolyte medium. This will enable reliable dynamic electrochemistry investigations into redox reactions at the solid/gas interface, free of any solvent defined potential window restrictions.