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Photodissociation of Water Using Solar Energy

IP.com Disclosure Number: IPCOM000089414D
Original Publication Date: 1977-Oct-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Freeouf, JL: AUTHOR

Abstract

An electrode is provided with high optical absorption in solar energy regime without photon-induced decomposition of electrode.

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Photodissociation of Water Using Solar Energy

An electrode is provided with high optical absorption in solar energy regime without photon-induced decomposition of electrode.

A semiconductor is used whose band gap is between nonbonding occupied states and the conduction band. In particular, the lone-pair semiconductors have a bulk density of occupied states (lone pair electrons) between the bonding and antibonding bands. Thus a moderate band gap (e.g., ~ 2 eV for Se) can be used for high optical absorption at photon energies suitable for solar cell conversion on earth, without breaking any bonds with the photon-created holes. If the proper band gap, E(F)-E(V), band-bending, etc., through simple systems (e.g., Se, Te, Se-Te alloys) is available, a simple and inexpensive means of hydrogen generation is obtainable.

The relevant band diagram is shown in Fig. 1. There is E(F) above E(O) (H/+//H(2)) and E(O)(H(2)O/O(2)) above the lone-pair holes. Lone pair holes are created via bulk optical absorption, and no external battery is necessary for the photodissociation process to proceed. Finally, the photon-created holes are in the nonbonding lone pair band, and should not cause the semiconductor to lose atoms into the electrolyte.

A working unit would be as shown in Fig. 2 wherein: possible semiconductors are S, Se, Te, As(2)S(3); possible metals are Au, Pt; and possible electrolytes are H(2)SO(4), NaOH. Preferably, the first semiconductor to be checked should be Se. It ha...