Hydrogen

Comparison and Reproducibility of H-Passivation of Si(100) with HF in Methanol, Ethanol, Isopropanol and Water by IBA, TMAFM, and FTIR'

by Nicole Herbots

V. Atluri*"#, N. Herbots*, D. Dagel" H. Jacobsson*,##, M. Johnson%, R. Carpio**, B. Fowler**
Department of Physics and Astronomy, Arizona State University, Tempe, AZ 85287-1504. *SEMATECH, Austin, TX 78741-6499.
#Presently at Intel Corporation., Chandler, AZ 85226. "•Presently at Ericsson Research Center, Molndal, Sweden.

V. Atluri*"#, N. Herbots*, D. Dagel" H. Jacobsson*,##, M. Johnson%, R. Carpio**, B. Fowler**
Department of Physics and Astronomy, Arizona State University, Tempe, AZ 85287-1504. *SEMATECH, Austin, TX 78741-6499.
#Presently at Intel Corporation., Chandler, AZ 85226. "•Presently at Ericsson Research Center, Molndal, Sweden.

Mat. Res. Soc. Symp. Proc. Vol. 477, pp. 281-292 (1997)

Three different HF:alcohol solutions are investigated to etch native Si0 2 and passivate Si(100) surfaces with H which... more Three different HF:alcohol solutions are investigated to etch native Si0 2 and passivate Si(100) surfaces with H which can the be desorbed at low temperature (T < 600'C). The resulting passivated Si(100) surfaces are compared using as a reference Si(100) passivated by a standard aqueous HF: solution (1:98 parts of HF: H2 0). After a modified RCA cleaning, Si(100) etched by HF:Methanol, HF:IPA, or HF:Ethanol, is characterized by Ion Beam Analysis (IBA), Tapping Mode Atomic Force Microscope (TMAFM), and Fourier Transform Infrared Spectroscopy (FTIR). The absolute coverage of 0 and C is measured by nuclear reaction analysis (NRA) combined with ion channeling at 3.05 MeV for 0 and 4.265 MeV for C. Hydrogen is measured via the elastic recoil detection (ERD) of 4He2+at 2.8 MeV.
Compared to aqueous HF, HF:alcohol passivates Si(100) leaving a lower 0 residue by an average factor of 0.62 and a similar C residue. H coverage is higher by an average factor of 1.43. Surface coverages are found to be reproducible in average by 1.4 x 1014 atoms/cm2 for C, and by 1.25 x 1014 atoms/cm2 for 0 when measured by IBA on samples identically processed. H coverage is reproducible within 5.5% when measured by ERD.
Selective area analysis by TMAFM shows that an increasing number of particulates is responsible for the apparent increase in root-mean -square (nns) surface roughness when the rms is measured over a whole image. Taking this effect into account, all passivated surfaces exhibit similar roughness when compared to the original Si(100) surface with little difference between
alcohols and with the reference aqueous HF solution. FTIR in the attenuation total reflection (ATR) mode detected SiHx species mostly as a
dihydride. Both IBA and FTIR detected significant levels of oxygen on surfaces passivated HF in alcohol and aqueous HF. This indicates that while Si(100) exhibits more H when passivated with HF in alcohol and can be desorbed at lower temperature than when treated with aqueous HF, H is
not bonded to Si only but likely bonds into a more complex surface termination, such as SiOH.

Hacking, N. Eames, M. (2011), Forks in the Road: Contrasting Transition Pathways in the Delivery of Sustainable Hydrogen (Conference Paper at World Hydrogen Technologies Conference, Glasgow, 2011)

by Nick Hacking

This conference paper reviews the literature on hydrogen innovation systems and contrasts insights from two current... more This conference paper reviews the literature on hydrogen innovation systems and contrasts insights from two current European case studies: the United Kingdom and Germany. Specifically a conceptual framework derived from innovation systems literature will be used to explore the differing patterns of development and emerging innovation trajectories in the two countries. Whilst the UK has a science base with clear strengths in hydrogen production and storage R&D, a number of regionally based hydrogen demonstration projects and private sector actors with interests in hydrogen technology, national government has yet to stimulate a coordinated and sustainable innovation policy regime for hydrogen. Instead, national policy makers in the UK have largely focussed on prospects for electric vehicles. By contrast, in 2009 a memorandum of understanding (MOU) was signed between the German government and number of major automobile manufacturers, gas companies and energy utilities to coordinate a cross-sectoral approach to rolling out mass-produced hydrogen fuel cell vehicles by 2015. This has been under the banner of a countrywide „H2 Mobility‟ programme which aims to establish Germany as an economy that can meet Europe‟s low carbon targets for 2050 whilst simultaneously boosting parts of its domestic economy. Investment a public hydrogen refuelling network is part of the German economic stimulus package (Konjunkturpaket II). Overall, the paper concludes with an assessment of the broader societal and policy implications of these emerging national differences, and what this tells us about possible innovation pathways to a hydrogen economy in an increasingly capital- and carbon-constrained world.

Lower carbon cars by reducing dissipation in hydrogen hybrids

by Iain Staffell

published in the International Journal of Low-Carbon Technologies
co-authored with K. Kendall

Fossil fuel is the major source of energy for all forms of motor vehicle, with gasoline and diesel fuels dominating... more Fossil fuel is the major source of energy for all forms of motor vehicle, with gasoline and diesel fuels dominating our personal transport. Although biofuels have been used to inject some renewable energy into the transport system, imports of oil and gas to Europe, the USA and Japan continue to rise. A move to reduce energy consumption and carbon emissions by driving more efficient vehicles is therefore necessary. This paper considers a shift to reduced friction hydrogen electric vehicles that give three major benefits: (i) sourcing hydrogen from low carbon sources like wind, biomass, nuclear and solar; (ii) using an electric drivetrain to minimize energy conversion to heat; and (iii) reducing resistances to motion to give lower energy requirements for traction. This energy dissipation due to friction proves to be a complex mixture of tyre losses, brake adhesion, wind resistance, fuel conversion inefficiency, motor resistance, drivetrain losses, auxiliary power consumption and so on. By considering the addition of many loss terms, it is shown that the energy dissipation in fuel cell-powered vehicles resolves into a linear function of vehicle weight.

Results from the Microcab fuel cell vehicle demonstration at the University of Birmingham

by Iain Staffell

published in the Int. J. Electric and Hybrid Vehicles

The UK’s first fleet of hydrogen fuel cell vehicles – the Microcab H4 series – has been demonstrated at the University... more The UK’s first fleet of hydrogen fuel cell vehicles – the Microcab H4 series – has been demonstrated at the University of Birmingham for 21 months. The five prototypes have been used interchangeably as four-seat urban taxis and light goods vehicles around campus, accumulating over 4,000 km on the campus road network and being filled with 68 kg of hydrogen.

The performance and efficiency of these vehicles have been monitored in-situ throughout the trial, using custom-built data loggers for the fuel cell and other power-train components. This paper presents the key findings relating to the power-train performance and efficiency. While the peak tank-to-wheel efficiency was 27%, the Microcabs were found on average to be 18% efficient at converting hydrogen into tractive power. The causes of this loss in efficiency are analysed and discussed, and show that improving the control and interaction of the individual components would result in substantially improved vehicle performance.

The Energy and Fuel Data Sheet

by Iain Staffell

A compendium of basic data on common hydrocarbon and other fuels. A compendium of basic data on common hydrocarbon and other fuels.

Production of hydrogen and light hydrocarbons as a potential gaseous fuel from microwave-heated pyrolysis of waste automotive engine oil

by Su Shiung Lam

Published in International Journal of Hydrogen Energy, DOI: 10.1016/j.ijhydene.2011.12.016 (Article In Press).

Waste automotive engine oil was pyrolyzed in a continuous stirred bed reactor using microwave energy as the heat... more Waste automotive engine oil was pyrolyzed in a continuous stirred bed reactor using microwave energy as the heat source; the yield and characteristics of the incondensable gaseous products are discussed. The recovered gases (41 wt% yield) were found to contain substantial concentrations of light aliphatic hydrocarbons (up to 86 vol.%) that could potentially be used as a chemical feedstock or a fuel source to power the process, or to be reformed to produce hydrogen for use as a second-generation fuel. Examination of the composition of the gases also showed the formation of H2 (up to 19 vol.%) and CO that could also be used as a valuable syngas (with a H2 + CO content of up to 35 vol.%). The high yield of gaseous hydrocarbons can be attributed to the unique heating mode and chemical environment present during microwave-heated pyrolysis. The use of a microwave-heated bed of particulate-carbon showed advantages in transforming waste oil into valuable gases. Hence an environmentally unfriendly waste material can be transformed into a useful resource and serves as an alternative source of hydrogen or hydrocarbon energy. The recovery of valuable gases shows advantage over traditional destructive approaches and suggests excellent potential for recycling problematic waste oil.

A Solar Photobioreactor for the Production of Biohydrogen from Microalgae

by Daniel Robledo

Co-authored with  Luis Pantí, Pedro Chávez, Rodrigo Patiño

The green microalga Chlamydomonas reinhardtii is proposed to produce hydrogen in a low-cost system using the solarmore The green microalga Chlamydomonas reinhardtii is proposed to produce hydrogen in a low-cost system using the solar
radiation in Yucatan, Mexico. A two-step process is necessary with a closed photobioreactor, in which the algae are
firstly growth and then induced for hydrogen generation. Preliminary results are presented in this work with some
planning for the future. Different culture broths, temperatures and light intensities were tested for biomass and hydrogen
production in laboratory conditions. The first experiments in external conditions with solar radiation and without
temperature control have been performed, showing the potential of this technique at larger scales. However, some
additional work must be done in order to optimize the culture maintenance, particularly in relation with the temperature
control, the light radiation and the carbon dioxide supply, with the idea of keeping an economic production.

The car industry and the blow-out of the hydrogen hype

by Sjoerd Bakker

Working Paper

The hydrogen hype of the last decade has passed and it is now seemingly substituted by the electric vehicle hype. A... more The hydrogen hype of the last decade has passed and it is now seemingly substituted by the electric vehicle hype. A technological hype can have both positive as well as negative consequences. On the one hand it attracts sponsors for technology development but on the other hand the high expectations might result in disappointment and subsequent withdrawal of the sponsors. In this paper I ask the question to what extent the car industry has created the hype and how it has done so. The industry’s role is studied through their prototyping activities and accompanying statements on market entry. I conclude that the car industry has indeed inflated the hype, especially through its public statements on market release after the turn of the millennium. Furthermore, the industry has shown a double repertoire of both highly optimistic and more modest statements. From this I take that statements are used deliberately to serve the industry’s interests whenever needed. Without neglecting the positive outcomes of hype, public and private funding for R&D efforts, more modest promises could serve the development of sustainable mobility better.

Natural Gas Based Hydrogen Production Plant with Zero Carbon Dioxide Emission

by Jorge Pena Lopez

Electrochemistry of Hydrogen in the Room Temperature Ionic Liquid 1-Butyl-3-methylimidazolium Bis(trifluoromethylsulfonyl)imide: Dissolved Hydrogen “Lubricates” Diffusional Transport

by Leigh Aldous

Yao Meng, Leigh Aldous, and Richard G. Compton, J. Phys. Chem. C, 2011, 115 (29), pp 14334–14340.

http://pubs.acs.org/doi/abs/10.1021/jp205421q

We report the electrochemical characterization of bis(trifluoromethylsulfonyl)imide (H[NTf2]) and ferrocene in the... more We report the electrochemical characterization of bis(trifluoromethylsulfonyl)imide (H[NTf2]) and ferrocene in the room temperature ionic liquid (RTIL) 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C2mim][NTf2]) in the presence of dissolved hydrogen (H2). Chronoamperometric measurements in the presence of varying levels of H2 were used to determine the diffusion coefficient of H[NTf2] and ferrocene at 298 K in [C2mim][NTf2]. Upon saturation with H2 at 298 K, these were found to increase from 2.5 (±0.1) × 10–11 m2 s–1 and 4.7 (±0.1) × 10–11 m2 s–1 to 2.8 (±0.1) × 10–11 and 5.1 (±0.1) × 10–11 m2 s–1, respectively. It is believed that the physiochemical changes correspond to the H2 occupying the interstices and therefore resulting in a change in the permittivity of the space between ions of the RTIL, resulting in diminished Coulombic interactions and a net reduction in the RTILs viscosity. Even more significant changes were observed at 308 K, despite the dissolved H2 concentration being lower (4.4 mM H2 at 298 K, 4.0 mM H2 at 308 K). Arrhenius plots of the diffusion coefficient of ferrocene in the RTIL displayed a decrease in the diffusion activation energy from 29.5 kJ mol–1 in the absence of H2 to 20.5 kJ mol–1 upon saturation with H2. The activation energy of diffusion of H2 was also determined in an RTIL for the first time (13.7 kJ mol–1), and deviation of the mass transport of the small H2 molecule from the Stokes–Einstein relationship was confirmed.

http://pubs.acs.org/doi/abs/10.1021/jp205421q

Clean, efficient electrolysis of formic acid via formation of eutectic, ionic mixtures with ammonium formate

by Leigh Aldous

Leigh Aldous and Richard G. Compton. Energy Environ. Sci., 2010, 3, pp. 1587-1592.

http://dx.doi.org/DOI:10.1039/C0EE00151A

Formic acid is a promising compound with regard to hydrogen storage and generation, as it can be formed via the... more Formic acid is a promising compound with regard to hydrogen storage and generation, as it can be formed via the hydrogenation of CO2 and decomposed to form H2 and CO2. The electrochemistry of formic acid, aqueous solutions of ammonium formate, and ammonium formate/formic acid eutectic mixtures (1.0 : 1.25 mol/mol, respectively) have been investigated. The electrocatalytic oxidation of formic acid was observed in the eutectic mixtures, and bulk electrolysis at platinum electrodes demonstrated electrolysis of the formic acid to form H2 and CO2.

http://dx.doi.org/DOI:10.1039/C0EE00151A

Space and Terrestrial Solar Power Sources for Large-Scale Hydrogen Production-A Comparison

by Leopold Summerer

Space and Terrestrial Solar Power Sources for Large-Scale Hydrogen Production

by Leopold Summerer

Scenarios for the Hydrogen Society (Poster)

by Tabea Hirzel

Tomelloso 2011

Fossil sourced hydrogen projects as U.S. Department of Energy's (DOE) Nuclear Hydrogen Initiative (NHI) are linked to... more Fossil sourced hydrogen projects as U.S. Department of Energy's (DOE) Nuclear Hydrogen Initiative (NHI) are linked to centralized production and capital intensive investments providing, beyond technical challenges, high political implications. The far wider available source solar energy and modular combustion concepts, like Hydrogen II in Almeria, Spain and the DLR SSPS tower in Cologne, Germany (2008), on one hand, as well as hydrogen bioreactors (Welch’s hydrogen plant in Pennsylvania, USA), on the other hand, promote worldwide energy independence and, besides environmentally-friendly solutions. Their decentralized technology, could become a real people’s energy (Rifkin, 2003). The way energy is produced and consumed shapes human behaviour and social structures. Small scale on-site production combined with low cost energy as proposed by Blacklight (Mills, et al., 2009) make the switch from today's “carriers-refined petroleum and electricity” to the hydrogen home feasible (Victor, Heller, & Victor, 2003). This study analysis the possible socio- and geopolitical scenarios that will result from the direction of further technological development in hydrogen based power and advocates for decentralized, small scale projects due to their higher security and reliability, advantages in innovation processes, total efficiency and environmental sustainability as essential factors for future stability and progress in human societies.

Amperometric gas detection using RTIL solvents

by Leigh Aldous

R. G. Compton, L. Aldous, A. M. O'Mahony, E. I. Rogers and F. J. Del Campo, Electrochemical Society - 218th ECS Meeting Abstracts 2010, MA 2010-02 3, pp. 2162.

http://link.aip.org/link/?MAECES/1002/2162/1

Microelectrode studies of the voltammetry of various dissolved gases in Room Temperature Ionic Liquids (RTIL) will be... more Microelectrode studies of the voltammetry of various dissolved gases in Room Temperature Ionic Liquids (RTIL) will be reported. First, a specially designed cell will be described in which tiny volumes (~10 µL) of RTIL can be degassed under vacuum and then used for microdisc voltammetric experiments after equilibriation with a gas mixture of choice.


The use of double potential step chronoamperometry for the simultaneous determination of the diffusion coefficients and gas concentration will be described and illustrated with various examples.


The electrochemistry of the following gases will be discussed; oxygen,1 hydrogen,2 ammonia,3 hydrogen sulfide4 and sulfur dioxide.5 The unusual voltammetry of oxygen in some RTILs will be explained6 and the changed voltammetry in the presence of carbon dioxide will be discussed.7

Finally, the future use of microelectrode arrays for membrane free gas sensors will be discussed.8

References

1 R.G. Evans, O.V. Klymenko, S.A. Saddoughi, C. Hardacre, R.G. Compton, J. Phys. Chem. B, 108, 7878-7886, (2004).
2 D.S. Silvester, L. Aldous, C. Hardacre, R.G. Compton, J. Phys. Chem. B, 111, 5000-5007, (2007).
3 X.B. Ji, D.S. Silvester, L. Aldous, C. Hardacre, R.G. Compton, J. Phys. Chem. C, 111, 9562-9572, (2007).
4 A.M. O'Mahony, D.S. Silvester, L. Aldous, C. Hardacre, R.G. Compton, J. Phys. Chem. C, 112, 7725-7730, (2008).
5 L.E. Barrosse-Antle, D.S. Silvester, L. Aldous, C. Hardacre, R.G. Compton, J. Phys. Chem. C, 112, 3398-3404, (2008).
6 A.S. Barnes, E.I. Rogers, I. Streeter, L. Aldous, C. Hardacre, G.G. Wildgoose, R.G. Compton, J. Phys. Chem. C, 112, 13709-13715, (2008).
7 L.E. Barrosse-Antle, C Hardacre, R.G. Compton, J. Phys. Chem. B, 113, 2805-2809, (2009).
8 X.-J. Huang, L. Aldous, A.M. O’Mahony, F. J. del Campo, R.G. Compton, Anal. Chem., accepted (2010).

http://link.aip.org/link/?MAECES/1002/2162/1

Ignition propensity of hydrogen/air mixtures impinging on a platinum stagnation surface

by Kyle Brady

An experimental investigation into the ignition characteristics of lean pre-mixed hydrogen/air mixtures is conducted... more An experimental investigation into the ignition characteristics of lean pre-mixed hydrogen/air mixtures is conducted using a stagnation-point flow configuration against a platinum surface, with a special emphasis on the determination of potential fire safety hazards associated with hydrogen release in the presence of a catalyst. Two distinct regimes are observed for this system – catalytic surface reactions and gas-phase ignition. It is demonstrated that depending on mixture equivalence ratio, catalytic surface reactions can be initiated with or without surface heating. When significant surface heat is released via catalytic reactions, gas-phase ignition can be induced, greatly increasing the apparent danger of hydrogen leaks in the presence of a platinum surface. The critical surface temperatures leading to catalytic ignition for hydrogen/air mixtures over a platinum surface are further investigated over a range of equivalence ratios and stretch rates. It is shown that ultra-lean hydrogen/air mixtures can be catalytically ignited even in the absence of external heat addition, suggesting that hydrogen leakage in the presence of a platinum surface may pose a fire safety risk even at room temperature. Furthermore, even without a transition to gas-phase ignition, the surface temperature that can be sustained with surface reactions alone may contribute to component degradation or itself pose a safety hazard.

Dissociation Rates of Urea in the Presence of NiOOH Catalyst: A DFT Analysis

by Damilola Daramola

Journal of Physical Chemistry A 2010, 114, pp11513 - 11521

Single molecule reactions have been studied between nickel oxyhydroxide, urea, and the hydroxide ion to understand the... more Single molecule reactions have been studied between nickel oxyhydroxide, urea, and the hydroxide ion to understand the process of urea dissociation into ammonia, isocyanic acid, cyanate ion, carbon dioxide, and nitrogen. In the absence of hydroxide ions, nickel oxyhydroxide will catalyze urea to form ammonia and isocyanic acid with the rate-limiting step being the formation of ammonia with a rate constant of 1.5 × 10−6 s−1. In the presence of hydroxide, the evolution of ammonia was also the rate-limiting step with a rate constant of 1.4 × 10−26 s−1. In addition, desorption of the cyanate ion presented an energy barrier of 6190 kJ mol−1 suggesting that the cyanate ion cannot be separated from NiOOH unless further reactions occurred. Finally, elementary dissociation reactions with hydroxide ions deprotonating urea to produce nitrogen and carbon dioxide were analyzed. These elementary reactions were investigated along three paths differing in the order that protons were removed and the nitrogen atoms were rotated. The rate-limiting step was found to be the removal of carbon dioxide with a rate constant of 4.3 × 10−65 s−1. Therefore, the catalyst could be deactivated by the surface blockage caused by carbon dioxide adsorption.

High Capacity Hydrogen Generation on-Demand From (NH3á+ áLiAlH4)

by Vitalie Stavila