[Due to the increasing size of the archives, each topic page now contains only the prior 365 days of content. Access to older stories is now solely through the Monthly Archive pages or the site search function.]
UW-Madison team develops novel hydrogen-producing photoelectrochemical cell using solar-driven biomass conversion as anode reaction
March 11, 2015
Researchers at the University of Wisconsin-Madison have developed an innovative hydrogen-producing photoelectrochemical cell (PEC), using solar-driven biomass conversion as the anode reaction. In a paper in the journal Nature Chemistry, the duo reports obtaining a near-quantitative yield and 100% Faradaic efficiency at ambient conditions without the use of precious-metal catalysts for this reaction, which is also thermodynamically and kinetically more favorable than conventional water oxidation at the anode. They thus demonstrated the utility of solar energy for biomass conversion (rather than catalysts) as well as the feasibility of using an oxidative biomass conversion reaction as an anode reaction in a hydrogen-forming PEC.
Chemistry Professor Kyoung-Shin Choi and postdoc Hyun Gil Cha said that their results suggest that solar-driven biomass conversion can be a viable anode reaction that has the potential to increase both the efficiency and the utility of PECs constructed for solar-fuel production.
Harvard hybrid “bionic leaf” converts solar energy to liquid fuel isopropanol
February 10, 2015
Scientists from a team spanning Harvard University’s Faculty of Arts and Sciences, Harvard Medical School and the Wyss Institute for Biologically Inspired Engineering at Harvard University have developed a scalable, integrated bioelectrochemical system that uses bacteria to convert solar energy into a liquid fuel. Their work integrates water-splitting catalysts comprising earth-abundant components with wild-type and engineered Ralstonia eutropha bacteria to generate biomass and isopropyl alcohol. An open access paper describing their work is published in Proceedings of the National Academy of Sciences (PNAS).
Pamela Silver, the Elliott T. and Onie H. Adams Professor of Biochemistry and Systems Biology at HMS and an author of the paper, calls the system a bionic leaf, a nod to the solar water-splitting artificial leaf invented by the paper’s senior author, Daniel Nocera, the Patterson Rockwood Professor of Energy at Harvard University. (Earlier post.)
HZB researchers characterize efficient manganese catalyst for artificial photosynthesis
January 22, 2015
Scientists at the Helmholtz Center for Materials and Energy (HZB) in collaboration with the School of Chemistry and ARC Centre of Excellence for Electromaterials Science at Monash University, Australia, have precisely characterized the electronic states of a manganese (Mn) water-splitting catalyst for artificial photosynthesis.
The team led by Professor Emad Aziz, head of the HZB Institute “Methods for Material Development“ and Professor Leone Spiccia from Monash University investigated the changes in the local electronic structure of the Mn 3d orbitals of a Mn catalyst derived from a dinuclear MnIII complex during the water oxidation cycle using X-ray absorption spectroscopy (XAS) and resonant inelastic X-ray scattering (RIXS) analyses.
GWU team uses one-pot process to co-generate H2 and solid carbon from water and CO2; solar fuels
December 30, 2014
|One-pot electrolytic process produces H2 and solid carbon from water and CO2. Li et al. Click to enlarge.|
A team at George Washington University led by Professor Stuart Licht has simultaneously co-generated hydrogen and solid carbon fuels from water and CO2 using a mixed hydroxide/carbonate electrolyte in a “single-pot” electrolytic synthesis at temperatures below 650 ˚C. The work is a further development of their work with STEP (solar thermal electrochemical process)—an efficient solar chemical process, based on a synergy of solar thermal and endothermic electrolyses, introduced by Licht and his colleagues in 2009. (Earlier post, earlier post.) (In short, STEP uses solar thermal energy to increase the system temperature to decrease electrolysis potentials.)
Licht and his colleagues over the past few years have delineated the solar, optical, and electronic components of STEP. In this study, they focused on the electrolysis component for STEP fuel, producing hydrogen and graphitic carbon from water and carbon dioxide. A paper on the new work is published in the journal Advanced Energy Materials.
Caltech team proposes taxonomy for solar fuels generators; different approaches to converting sunlight to chemical fuels
December 22, 2014
Researchers at the California Institute of Technology are proposing a nomenclature and taxonomy for solar fuels generators—devices that harness energy from sunlight to drive the synthesis of chemical fuels. A number of different approaches to this technology are being pursued, many of which can be differentiated by the physical principles on which they are based, according to the Caltech team, led by Dr. Nathan Lewis.
In an open-access paper published in the RSC journal Energy & Environmental Science, Dr. Lewis and colleagues outlined their method of using the source of the asymmetry that separates photogenerated electronics and holes as the basis for their taxonomy. They identify three basic device types: photovoltaic cells, photoelectrochemical cells, and photoelectrosynthetic particulate/molecular photocatalysts.
New efficient catalytic system for the photocatalytic reduction of CO2 to hydrocarbons
December 04, 2014
|Photocatalytic reduction products formed on various catalysts. The Au3Cu@STO/TiO2 array (red arrow) was the most reactive photocatalyst in this family to generate hydrocarbons from diluted CO2. Kang et al. Click to enlarge.|
Researchers from Japan’s National Institute for Materials Science (NIMS) and TU-NIMS Joint Research Center, Tianjin University, China have developed a new, particularly efficient photocatalytic system for the conversion of CO2 into CO and hydrocarbons. The system, reported in a paper in the journal Angewandte Chemie, may be a step closer to CO2-neutral hydrocarbon fuels.
More than 130 kinds of photocatalysts have been investigated to catalyze CO2 reduction; of those, strontium titanate (SrTiO3, STO) and titania (TiO2) are two of the most investigated materials. The research team headed by Dr. Jinhua Ye decided to use both, and devised a heteromaterial consisting of arrays of coaxially aligned STO/TiO2 nanotubes.
Toshiba targeting practical implementation of conversion of solar energy and CO2 to feedstock and fuel in 2020s
December 03, 2014
|Mechanism of the technology. Source: Toshiba. Click to enlarge.|
Toshiba Corporation has developed a new technology that uses solar energy directly to generate carbon compounds from carbon dioxide and water, and to deliver a viable chemical feedstock or fuel with potential for use in industry. Toshiba introduced the technology at the 2014 International Conference on Artificial Photosynthesis (ICARP2014) on 26 November.
The long-term goal of the research work is to develop a technology compatible with carbon dioxide capture systems installed at facilities such as thermal power stations and factories, utilizing carbon dioxide to provide stockable and trailerable energy. Towards this, Toshiba said it will further improve the conversion efficiency by increasing catalytic activity, with the aim of securing practical implementation in the 2020s.
Researchers develop free-standing nanowire mesh for direct solar water-splitting to produce H2; new design for “artificial leaf”
|The mesh with BiVO4 nanowire photoanode for water oxidation and Rh-SrTiO3 nanowire photocathode for water reduction produces hydrogen gas without an electron mediator. Credit: ACS, Liu et al. Click to enlarge.|
Researchers from UC Berkeley, Lawrence Berkeley National Laboratory and Nanyang Technological University, Singapore have developed a new technology for direct solar water-splitting—i.e., an “artificial leaf” to produce hydrogen—based on a nanowire mesh that lends itself to large-scale, low-cost production. A paper describing their work is published in the journal ACS Nano.
In the design, semiconductor photocatalysts are synthesized as one-dimensional nanowires, which are assembled into a free-standing, paper-like mesh using a vacuum filtration process from the paper industry. When immersed in water with visible light irradiation (λ ≥ 400 nm), the mesh produces hydrogen gas. Although boosting efficiency remains a challenge, their approach—unlike other artificial leaf systems—is free-standing and doesn’t require any additional wires or other external devices that would add to the environmental footprint.
Solar fuels company Joule looks to partner with Scatec Solar to bring photovoltaic power to Joule production plants
September 05, 2014
Joule, the developer of a direct, single-step, continuous process for the production of solar hydrocarbon fuels (earlier post), has entered into a memorandum of understanding (MoU) with Scatec Solar ASA, a leading, independent solar power producer. In the MoU the parties have agreed to initiate a process to reach specific terms for a partnership, to support the roll-out of Joule production plants featuring photovoltaic power.
The terms of the MoU anticipate that Scatec Solar ASA will become preferred supplier and operator of photovoltaic power installations for Joule plants, with an initial deployment goal of up to 25,000 acres (~10,000 hectares) and a power requirement of 2 gigawatts. A deployment of this scale would generate up to 625 million gallons (~15 million barrels) of ethanol or 375 million gallons (~9 million barrels) of diesel per year, while consuming about 4 million tonnes of industrial waste CO2 annually in the process.
Molecular shuttle speeds up hydrogen production by the photocatalytic splitting of water
August 15, 2014
In their latest experiments with semiconductor nanocrystals as light absorbers, physicists led by Professor Jochen Feldmann (Ludwig-Maximilians-Universität München, LMU Munich), in collaboration with a team of chemists under the direction of Professor Andrey Rogach (City University of Hong Kong), have succeeded in significantly increasing the yield of hydrogen produced by the photocatalytic splitting of water.
The crucial innovation, reported in the latest issue of the journal Nature Materials, is the use of a so-called molecular shuttle to markedly improve the mobility of charge carriers in their reaction system.
DOE awards $100M in 2nd funding round for 32 Energy Frontier Research Centers
June 24, 2014
The US Department of Energy (DOE) is awarding $100 million in the second round of funding for Energy Frontier Research Centers (EFRCs); research supported by this initiative will enable fundamental advances in energy production, storage, and use.
The 32 projects receiving funding were competitively selected from more than 200 proposals. Ten of these projects are new while the rest received renewed funding based both on their achievements to date and the quality of their proposals for future research.
Study suggests energy and GHG impacts of synthetic hydrocarbon fuels from CO2 are greater than impacts of existing hydrocarbon fuels
June 06, 2014
|Synthetic fuel production from fuel-combustion-based energy and CO2 (top) and from atmospheric CO2 using solar electricity (bottom). Credit: ACS, van der Giesen et al. Click to enlarge.|
Researchers at the Institute of Environmental Sciences at Leiden University, The Netherlands) have concluded that the energy demand and climate impacts of using CO2 to produce synthetic hydrocarbon fuels by using existing technologies can be greater than the impacts of existing hydrocarbon fuels. Their quantitative lifecycle assessment of the environmental merits of liquid hydrocarbon fuels produced from CO2, water and energy compared to alternative fuel production routes is published in the ACS journal Environmental Science & Technology.
In their study, the researchers evaluated five hypothetical production routes using different sources of CO2 and energy. The team undertook the work specifically to investigate four general arguments that have been proposed in support of such fuels:
SOLAR-JET project demonstrates solar-driven thermochemical conversion of CO2 and water to jet fuel
April 28, 2014
|SOLAR-JET concentrated thermochemical reactor. Red arrow indicates ceria reduction (oxygen evolution); blue arrow indicates oxidation (fuel production). Click to enlarge.|
The EU-funded SOLAR-JET project has demonstrated the production of aviation kerosene from concentrated sunlight, CO2 captured from air, and water. The process has also the potential to produce any other type of fuel for transport applications, such as diesel, gasoline or pure hydrogen in a more sustainable way.
SOLAR-JET (Solar chemical reactor demonstration and Optimization for Long-term Availability of Renewable JET fuel) uses sunlight in a concentrated solar reactor to convert CO2 and water to syngas (a mixture of hydrogen and CO), which is then processed in a Fischer-Tropsch reactor to aviation kerosene.
New mesoporous crystalline Si exhibits increased rate of H2 production; potential use in Li-ion batteries also
April 11, 2014
|Schematic of mesoporous silicon Image: Donghai Wang/Penn State. Click to enlarge.|
Researchers at Penn State have devised a new process for the bottom-up synthesis of mesoporous crystalline silicon materials with high surface area and tunable primary particle/pore size via a self-templating pore formation process.
The nanosized crystalline primary particles and high surface areas enable an increased rate of photocatalytic hydrogen production from water and extended working life. These advantages also make the mesoporous silicon a potential candidate for other applications, such as optoelectronics, drug delivery systems and even lithium-ion batteries. A paper on their work is published in Nature Communications.