Photoelectrochemical reactions for solar energy conversion. 1. Photoeffects at the p-Si/liquid electrolyte interface. 2. Catalytic CO/sub 2/ reduction

Thesis/Dissertation · Sun Jan 01 00:00:00 EST 1984

OSTI ID:5923719

Vlachopoulos, N A

In recent years, chemical methods for solar energy conversion and storage have been the focus of extensive fundamental research. The first chapter of this dissertation examines endoergic reactions involving excitation of a photoactive molecule as candidates for the storage of radiant energy. By increasing the light intensity to an appropriate level, one can lessen the deleterious effects on energy conversion of the reverse exoergic process. Subsequently, photoelectrochemical reactions based on the excitation by light of a p-type semiconductor electrode immersed in an electrolytic solution are discussed. Photoproduced electrons are driven to the electrode surface, where they can participate in reductive reactions. Experiments were performed at a p-type silicon rotating disk photoelectrode effecting the reduction of a tetraazomacrocyclic complex of nickel. The transition between a current proportional to light intensity and a mass-transport-limiting current occurs when either the light intensity varies while the mass transport conditions are maintained constant or vice versa. Finally, the application of p-type silicon photocathodes in electrochemical cells reducing CO/sub 2/ to CO was considered. Such a reaction can take place at a potential approaching the thermodynamic value if a tetraazomacrocyclic complex of nickel or cobalt is introduced in the solution as an electron transfer mediator between photoelectrode and CO/sub 2/. This system is one of the most efficient reported to date for the electrochemical reduction of CO/sub 2/.

• OSTI ID: 5923719
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
30 DIRECT ENERGY CONVERSION
CARBON DIOXIDE
REDUCTION
PHOTOANODES
MATERIALS
PHOTOCATHODES
PHOTOELECTROCHEMICAL CELLS
ELECTRODES
THERMOCHEMICAL HEAT STORAGE
SILICON
ELECTROCHEMISTRY
SOLAR ENERGY CONVERSION
P-TYPE CONDUCTORS
REDOX REACTIONS
ANODES
CARBON COMPOUNDS
CARBON OXIDES
CATHODES
CHALCOGENIDES
CHEMICAL REACTIONS
CHEMISTRY
CONVERSION
ELECTROCHEMICAL CELLS
ELEMENTS
ENERGY CONVERSION
ENERGY STORAGE
EQUIPMENT
HEAT STORAGE
OXIDES
OXYGEN COMPOUNDS
SEMICONDUCTOR MATERIALS
SEMIMETALS
SOLAR EQUIPMENT
STORAGE
140505* - Solar Energy Conversion- Photochemical
Photobiological
& Thermochemical Conversion- (1980-)
300505 - Fuel Cells- Electrochemistry
Mass Transfer & Thermodynamics