Frontiers of Engineering Reports on Leading-Edge Engineering from the 2013 Symposium (2014) / Chapter Skim
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Artificial Solar Fuel Generators--Miguel A. Modestino and Rachel A. Segalman
Artificial Solar Fuel Generators--Miguel A. Modestino and Rachel A. Segalman
Pages 97-108
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From page 97... ...
Adoption of solar power generation will entail significant changes in operation of the power grid, as classical power generation plants will need to respond not only to changes in consumer demand but also to non ontrollable variations in energy generation. c Background One option to mitigate the intermittency of solar energy generation is the incorporation of energy storage capacity into the grid, so that fluctuations in energy generation are buffered and do not affect the operation of the electricity distribution channels.
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From page 98... ...
Solar-driven CO2 reduction poses greater technical challenges because the number of electron transfer steps in the reactions is higher, the concentration of CO2 in electrolytes is generally low, and the diversity of products makes the necessary separation more difficult. Mechanics of Solar Fuel Generators As shown in Figure 1, solar fuel generation begins with the absorption of light to form charges that are used to drive oxidation and reduction reactions.
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From page 99... ...
(B) A PEC device contains photovoltaic units that absorb light and move charges to catalytic centers, where electrochemical hydrogen and oxygen evolution r eactions take place.
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From page 100... ...
Solar Fuel Generation Systems Since the first demonstration of solar-driven water splitting by Fujishima and Honda (1972) , the prospect of using PEC cells for solar fuel generation has motivated the quest for components and integrated systems that can continuously and robustly produce hydrogen fuels directly from sunlight.
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From page 101... ...
Mesoscale Building Blocks for Artificial Photosynthesis Systems The examples cited above represent initial attempts at developing integrated devices that can produce hydrogen fuels directly from the sun, and they all rely on macroscopic PEC units arranged such that ion transport involves a liquid electrolyte. Under concentrated electrolyte conditions (~1 M)
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From page 102... ...
The incorporation of mesoscale PEC units into fully functional solar hydrogen generators represents a promising alternative to overcome the technological challenges that prevent deployment, and so a great deal of research is being conducted in this area. Membrane Materials for Artificial Photosynthesis Membranes in solar hydrogen generators serve two basic functions: to provide pathways for ion conduction and to keep gaseous products separated (as shown in Figure 2)
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From page 103... ...
In the case of artificial photosynthesis applications, the operating current density is dictated by the solar absorption rate and is relatively low when com pared to the requirements for other similar devices, but very sensitive to crossover due to the relatively small quantity of product. Moreover, the presence of a large number of interfaces between the polymer and inorganic PEC components can severely affect the structure and transport properties of common nanostructured fuel cell membrane materials.
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From page 104... ...
Several electrochemical modeling studies provide some guidance on the optimal arrangements and dimensions of each of the components in an integrated solar hydrogen generator (Berger and Newman 2013; Haussener et al. 2012; Surendranath et al.
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From page 105... ...
2011. Synthesis and gas separation performance of triblock copolymer ion gels with a polymerized ionic liquid mid-block.
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From page 106... ...
2013. A monolithic device for solar water splitting based on series interconnected thin film absorbers reaching over 10% solar-to hydrogen efficiency.
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From page 107... ...
2011. Electrical conductivity, ionic con ductivity, optical absorption, and gas separation properties of ionically conductive polymer mem branes embedded with Si microwire arrays.
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