Generation of hydrogen using hematite (. cap alpha. -Fe/sub 2/O/sub 3/) electrode

Conference · Thu Dec 01 00:00:00 EST 1983 · Alternative Energy Sources; (United States)

OSTI ID:6722866

Bhardwaj, R C; Jadhav, C M; Khan, M M.T.

Recent reports by Somorjai produced considerable interest in photocatalytic production of hydrogen from water using P- and ntype polycrystalline iron oxide assembly. The authors report the constant generation of hydrogen using semi-conductor electrode of hematite (..cap alpha..-Fe/sub 2/O/sub 3/) available in nature. The naturally occurring hematite was ground and powdered, the powder then pressed in the form of pellets of 0.8 cm/sup 2/ diameter and connected with a copper lead using silver eposy. The P-type Fe/sub 2/O/sub 3/ electrode was prepared by pressing the ..cap alpha..-Fe/sub 2/O/sub 3/ powder with fine powder of MgO (different weight percentage) and heating them in air at 1350 - 1400/sup 0/C in air. When both electrodes were connected and dipped in 0.1 M Na/sub 2/SO/sub 4/ aqueous solution, hydrogen was evolved at the rate 3 X 10/sup 5/ molecules/hr on irradiation with 450 W xenon lamp. The hydrogen was detected by gas chromatography. It was observed that the production of hydrogen decreases with time and stops completely after sometime. The reactivation by flowing oxygen gas through the reaction cell for an hour, as reported by Somorjai, was not successful. This may have been due to the deterioration of p-type samples by gradual reduction of the iron oxide surfaces by a small fraction of the photoproduced hydrogen. This deterioration was stopped up to a certain extent by deposition of a thin film of indium on the p-type electrode. The progress to improve the efficiency of this system is being accomplished by changing the grain size of polycrystalline iron oxide and by depositing different metal films of different thickness on p-type electrode. It appears from preliminary observations that hematite available in nature contains impurities of SiO/sub 2/ and, on heating at higher temperatures, the hematite (..cap alpha..-Fe/sup 2/O/sub 3/) becomes doped automatically and gives an n-type electrode. The spectral studies show that it absorbs maximum light at 390 nm.

• Research Organization: Central Salt and Marine Chemicals Research Institute, Bhavnagar
• OSTI ID: 6722866
• Report Number(s): CONF-831205-
• Journal Information: Alternative Energy Sources; (United States), Conference: 6. Miami international conference on alternative energy sources, Miami Beach, FL, USA, 12 Dec 1983
• Country of Publication: United States
• Language: English

Related Subjects

08 HYDROGEN
AQUEOUS SOLUTIONS
PHOTOELECTROLYSIS
ELECTRODES
CHEMICAL COMPOSITION
PELLETIZING
HYDROGEN PRODUCTION
ELECTROLYSIS
IRON OXIDES
GRINDING
PARTICLE SIZE
ELECTROCATALYSTS
HEMATITE
LIGHT BULBS
N-TYPE CONDUCTORS
P-TYPE CONDUCTORS
PHOTOELECTROLYTIC CELLS
POLYCRYSTALS
CATALYSTS
CHALCOGENIDES
COMMINUTION
CRYSTALS
DISPERSIONS
ELECTROCHEMICAL CELLS
ELECTROLYTIC CELLS
EQUIPMENT
FABRICATION
IRON COMPOUNDS
IRON ORES
LYSIS
MACHINING
MATERIALS
MINERALS
MIXTURES
MOLDING
ORES
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PHOTOELECTROCHEMICAL CELLS
SEMICONDUCTOR MATERIALS
SIZE
SOLAR EQUIPMENT
SOLUTIONS
TRANSITION ELEMENT COMPOUNDS
080101* - Hydrogen- Production- Electrolysis