NOVELTY - A photocatalyst reaction plate (50) has a photocatalyst (52) in an oxidation tub (14), to absorb optical energy and generate electron hole pairs. A metal (54) connected to the photocatalyst, reduces the internal resistance of electron transmission in the photocatalyst and prevents the recombination of electron and holes. A conductive carrier (56) connected to the metal transmits the electrons to a reduction electrode (58) in a reduction tub (16).    USE - Used for decomposing water, to generate hydrogen and carbon dioxide into energy generating fuel used in chemical substance or solar energy and hydrogen energy field.    ADVANTAGE - The separation rate of electron-holes is enhanced by preventing recombination of the electrons and holes.    DETAILED DESCRIPTION - A concentration different photochemical reactor comprises: a photochemical reaction tub, which has more than one solution for reactants, an oxidation tub, and a reduction tub, the solution in the oxidation tub having a pH of 6-11, the solution in the reduction tub having a pH of 2-7, and where the pH value of the former is higher than the pH value of the latter; and a photocatalyst reaction plate, which is installed in the photochemical reaction tub and has in sequence: a photocatalyst, which is provided in the oxidation tub to receive optical energy, to generate electron-hole pairs, and to have the holes participate an oxidation reaction; a metal, which is connected to the photocatalyst to form a low contact resistance with the photocatalyst, preventing the electrons and the holes from recombination; a conductive carrier, which is connected to the metal for transmitting the electrons; and a reduction electrode, which is provided in the reduction tub and connected to the conducive carrier to receive the electrons and to have the electrons participate in a reduction reaction.    DESCRIPTION OF DRAWING(S) - The figure shows side and cross-sectional views of the photochemical reaction tub of the concentration different photochemical reactor.    photochemical reaction tub (10)    oxidation tub (14)    reduction tub (16)    photocatalyst reaction plate (50)    photocatalyst (52)    metal (54)    conductive carrier (56)    reduction electrode (58)