英文-无机纳米材料光解水ppt课件

▪ in 1971 by Fujishima and Honda
▪ suspended semiconductor particles:
▪ Bard demonstrated the photocatalytic effects
three main strategies
Coat conventional photovoltaic cells with 1 cocatalysts for water splitting or with
protecting layers to inhibit photocorrosion
Development of new metal oxide materials 2 that combine suitable properties for
➢ Electricity is difficult to store and to distribute over long distances.
1 Introduction
▪ Converting the photochemical energy directly into fuel: H2O →1/2 O2(g) + H2(g); ∆G = +237 kJ/mol
Photoelectrochemical devices
▪ The best performing photoelectrochemical devices known today are Tandem cells.
▪ a combination of two or more semiconductors connected in series
▪ Efficiencies between 12.4% and over 18% have been achieved, i.e. about half of the theoretical efficiency limit for these devices.
▪ But the performance cannot be sustained.
2 Brief history of nanoscale photoelectrochemistry and photocatalysis
▪ Modern nanoscience:
▪ only about 40 years old, began in 1974 with Dingle’s discovery of quantum size effects in thin films
▪ The photoelectrode materials are not stable under operating conditions and undergo photocorrosion.
▪ Similar stability problems exist for most other visible light absorbing II–VI, III–V, and group 14 element semiconductors.
1 Introduction
photovoltaic cells
✓ The solar energy can be converted into electricity
with up to 43.5% efficiency.
➢ These cells are more expensive than virtually ‘free’ coal.
▪ Several ways to facilitate reaction:
Photovoltaic cell plus electrolyzer Thermochemical methods, etc.
▪ The most economical ones:
Photoelectrosynthetic cells (PECs) Suspended photocatalysts
▪ Photoelectrochemistry:
▪ started in 1955 with Brattain’s electrochemical studies on germanium electrolyte junctions
▪ Water photoelectrolysis at illuminated TiO2 electrodes:
▪ Semiconductors with smaller bandgaps can be used, can absorb a greater fraction of the solar spectrum
Photoelectrochemical devices
Photoelectrochemical devices
Inorganic nanostructures for photoelectrochemical and photocatalytic
water splitting
Frank E. Osterloh
University of California, Davis Department of Chemistry
photoelectrochemical water splitting
Exploit scaling laws and specific effects at 3 the nanoscale to enhance the efficiency of
existing semiconductors and metal oxides
Contents
1
Introduction
2
Brief history
3 c nanostructures
4 Conclusion and outlook
carbon free energy technology
The solar energy received on the Earth’s surface meets current and future human energy demand.