EES Blog

Researchers in Atlanta, GA have developed a device that produces hydrogen gas from waste heat, solar, and/or mechanical energies.

Recent research conducted at Georgia Institute of Technology by Yang and coworkers have developed a new hybrid energy harvesting device to aid in the effort of hydrogen fuel production. Currently, hydrogen gas for use in industry is predominantly generated by steam reformation of methane or natural gas. This method produces greenhouse gas, requires high temperatures, and utilizes non-renewable resources.

Electrolytic production of hydrogen from water is one popular contender, due to its simplicity and abundance of reactants, however it is currently a more expensive process than through steam reformation. By developing a hybrid device that can take advantage of multiple modes of otherwise wasted energy, an “ambient” fuel generator can be realized.

The novelty in the present work is the combination of solar, thermal, and mechanical energies in the electrolysis of water. By matching a Si-pyramid solar cell with a Bi₂Te₃ based thermoelectric cell, along with a polyamide-perfluoroalkoxy based triboelectric nanogenerator, simultaneous energy harvesting can occur under a variety of environmental conditions. The group has reported H₂ gas production at a rate of 4 x10^-4 mL/s under hybrid generation mode. The technology can also be made to charge a Li-ion battery for on-demand hydrogen production, to compensate for environmental fluctuations.

With optimization, technology such as this can one day exist as a remote platform on the open ocean, passively generating hydrogen gas to be either pipelined to land, or used immediately for fuel cell powered ships.

by David Novitski

Interested? Read the full communication in Energy and Environmental Science here:

A hybrid energy cell for self-powered water splitting
Ya Yang, Hulin Zhang, Zong-Hong Lin, Yan Liu, Jun Chen, Ziyin Lin, Yu Sheng Zhou, Ching Ping Wonga and Zhong Lin Wang
Energy Environ. Sci., 2013, Advance Article
DOI: 10.1039/C3EE41485J

In their recent perspective article in Energy and Environmental Science, Professor Doron Aurbach and co-workers highlight key developments in magnesium-ion battery technology.

Rechargeable batteries are ubiquitous in portable electronics, and are expected to play an important role in electric vehicles and grid storage in the future. While lithium-ion technology is the current state of the art, concerns remain about the supplies of lithium on Earth. As such, alternative systems such as magnesium-ion batteries are being developed. Magnesium is the fifth most abundant element in the Earth’s crust and its bivalency means that it can in principle store more energy per unit volume than lithium metal.

A key requirement in magnesium-ion battery technology is reversible deposition of magnesium on the magnesium metal anode. However, most organic solvents and simple magnesium salts react with magnesium to form a so-called passivation layer on the anode, precluding reversible magnesium deposition and further charge-discharge cycles. Vital progress was made with the discovery of electrolytes that were stable in the presence of the magnesium anode. In particular, reaction of AlCl_3-nR_n lewis acids with R₂Mg lewis bases in ether solvents yielded electrolyte solutions which were stable up to voltages of 2.1 V vs. magnesium metal. The combination of these so-called dicholoro-complex (DCC) electrolytes with Chevrel phase intercalation cathodes (e.g. Mo₆S₈) and magnesium anodes yielded the first working prototypes for reversible magnesium-ion batteries.

While these first prototypes constituted a great breakthrough, relatively low energy densities and lacking performance at high rates precluded their commercialisation. Ongoing work focuses on finding new electrolytes with wider electrochemical stability windows, as well as new cathode and anode materials. One interesting possibility is to replace the magnesium anode with metal alloys of bismuth and antinomy, sidestepping the problems associated with the reactivity of magnesium and allowing more conventional electrolytes to be used.

Read more in the perspective article in Energy and Environmental Science:

Mg rechargeable batteries: an on-going challenge
Hyun Deog Yoo, Ivgeni Shterenberg, Yosef Gofer, Gregory Gershinsky, Nir Pour and Doron Aurbach
Energy Environ. Sci., 2013, Advance Article
DOI: 10.1039/C3EE40871J

By Alexander Forse

Take a look at our selection of exciting articles that have been recently published online:

Post-combustion carbon dioxide capture using electrochemically mediated amine regeneration
Michael C. Stern, Fritz Simeon, Howard Herzog and T. Alan Hatton
DOI: 10.1039/C3EE41165F

Improving the long-term stability of PBDTTPD polymer solar cells through material purification aimed at removing organic impurities
William R. Mateker, Jessica D. Douglas, Clément Cabanetos, I. T. Sachs-Quintana, Jonathan A. Bartelt, Eric T. Hoke, Abdulrahman El Labban, Pierre M. Beaujuge, Jean M. J. Fréchet and Michael D. McGehee
DOI: 10.1039/C3EE41328D

New materials based on a layered sodium titanate for dual electrochemical Na and Li intercalation systems
Mona Shirpour, Jordi Cabana and Marca Doeff
DOI: 10.1039/C3EE41037D

Towards high energy density sodium ion batteries through electrolyte optimization
Alexandre Ponrouch, Rémi Dedryvère, Damien Monti, Atif E. Demet, Jean Marcel Ateba Mba, Laurence Croguennec, Christian Masquelier, Patrik Johansson and M. Rosa Palacín
DOI: 10.1039/C3EE41379A

Charge transport in lithium peroxide: relevance for rechargeable metal–air batteries
Maxwell D. Radin and Donald J. Siegel
DOI: 10.1039/C3EE41632A

Thomas Jaramillo and co-workers developed of a very sensitive experiment to identify and quantify CO₂ electroreduction products. Their results, presented in their recent EES article, provide a comprehensive view of the reaction chemistry.

A recent C&EN article discusses the work of Jaramillo’s group. The C&EN article focuses on recent developments towards the interesting goal of converting CO₂ into useful products using electrochemistry: “Carbon dioxide gets a lot of attention—most of it negative—as a greenhouse gas. But if CO₂ could be converted in a cost-effective manner to valuable products, the ubiquitous small molecule so often reviled for its role in climate change might start to lose its bad rap.”

Read more in the C&EN article here…

…and read the article in EES:

New insights into the electrochemical reduction of carbon dioxide on metallic copper surfaces
Kendra P. Kuhl, Etosha R. Cave, David N. Abram and Thomas F. Jaramillo
DOI: 10.1039/C2EE21234J