Photochemical diodes

A process for converting optical energy into chemical energy to drive a chemical reaction in a matrix of chemical reactants which comprises suspending an assembly of discrete photochemical diodes in the reactant matrix and illuminating the diodes with optical energy, the diodes each comprising two portions, a first portion comprising at least one appropriately doped semiconductor material of a given conductivity type and provided with an ohmic contact over a portion thereof, and a second portion comprising either metal which is joined to said first portion through said ohmic contact or at least one appropriately doped semiconductor material of a given conductivity type opposite to that of said first portion, provided with an ohmic contact over a portion thereof and joined to said first portion through both said ohmic contacts.

A process for generating hydrogen from a portion of a body of water using solar radiation comprising

• suspending an assembly of discrete photochemical diodes in the water, the photochemical diodes comprising two portions, a first portion comprising at least one appropriately doped semiconductor material of a given conductivity type and provided with an ohmic contact over a portion thereof and a second portion comprising either metal which is joined to said first portion through said ohmic contact or at least one appropriately doped semiconductor material of a conductivity type opposite to that of said first portion, provided with an ohmic contact over a portion thereof and joined to said first portion through both said ohmic contacts,
• confining the diodes to a fixed volume element by membranes permeable to the water and impermeable to the diodes, and
• collecting evolved hydrogen in a space above the water formed by a transparent polymer film.

In combination:

• (a) a matrix of chemical reactants;
• and
• (b) an assembly of discrete photochemical diodes suspended in the reactant matrix, the photochemical diodes comprising two portions, a first portion comprising at least one appropriately doped semiconductor material of a given conductivity type and provided with an ohmic contact over a portion thereof and a second portion comprising either metal which is joined to said first portion through said ohmic contact or at least one appropriately doped semiconductor material of a conductivity type opposite to that of said first portion, provided with an ohmic contact over a portion thereof and joined to said first portion through both said ohmic contacts.