For chemical reactions, the zinc–zinc oxide cycle or Zn–ZnO cycle is a two step thermochemical cycle based on zinc and zinc oxide for hydrogen production with a typical efficiency around 40%.
The thermochemical two-step water splitting process uses redox systems:
Dissociation: ZnO → Zn + 1/2 O2
Hydrolysis: Zn + H2O → ZnO + H2
For the first endothermic step concentrating solar power is used in which zinc oxide is thermally dissociated at into zinc and oxygen. In the second non-solar exothermic step zinc reacts at with water and produces hydrogen and zinc oxide. The temperature level is realized by using a solar power tower and a set of heliostats to collect the solar thermal energy.
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The copper–chlorine cycle (Cu–Cl cycle) is a four-step thermochemical cycle for the production of hydrogen. The Cu–Cl cycle is a hybrid process that employs both thermochemical and electrolysis steps. It has a maximum temperature requirement of about 530 degrees Celsius. The Cu–Cl cycle involves four chemical reactions for water splitting, whose net reaction decomposes water into hydrogen and oxygen. All other chemicals are recycled.
For chemical reactions, the iron oxide cycle (Fe3O4/FeO) is the original two-step thermochemical cycle proposed for use for hydrogen production. It is based on the reduction and subsequent oxidation of iron ions, particularly the reduction and oxidation between Fe3+ and Fe2+. The ferrites, or iron oxide, begins in the form of a spinel and depending on the reaction conditions, dopant metals and support material forms either Wüstites or different spinels. The thermochemical two-step water splitting process uses two redox steps.
Thermochemical cycles combine solely heat sources (thermo) with chemical reactions to split water into its hydrogen and oxygen components. The term cycle is used because aside of water, hydrogen and oxygen, the chemical compounds used in these processes are continuously recycled. If work is partially used as an input, the resulting thermochemical cycle is defined as a hybrid one. This concept was first postulated by Funk and Reinstrom (1966) as a maximally efficient way to produce fuels (e.g.
This course will provide an introduction to fundamental concepts in microbiology. Special emphasis will be given to the surprising and often counter-intuitive physical world inhabited by microorganism
This course aims at giving an overview on the synthesis of nanoparticles, with more focus on colloidal chemistry, and their implementation into devices for energy applications (batteries, solar cells,
Solar-driven high-temperature electrolysis (HTE) and thermochemical cycles (TCC) are two promising pathways for fuel processing and energy storage, which are considered in this thesis. The goals of this thesis are: i) offering engineering guidelines at sys ...
The solar thermochemical cycle based on ceria is a promising route for renewable fuel production. The solar-to-fuel efficiency of a thermochemical reactor is highly dependent on the oxygen removal during the reduction step. Conventional nitrogen sweeping ( ...
AMER CHEMICAL SOC2022
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Multimetal oxyhydroxides have recently been reported that outperform noble metal catalysts for oxygen evolution reaction (OER). In such 3d-metal-based catalysts, the oxidation cycle of 3dmetals has been posited to act as the OER thermodynamic-limiting proc ...