TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Method: The reducing carbon dioxide further comprises irradiating light onto the carbon dioxide in the presence of a photocatalyst. The separating the oxygen from the carbon monoxide further comprises selectively passing oxygen through an ion transfer membrane, perovskite membrane, an yttria stabilized zirconia membrane, or a scandium-zirconium oxide membrane. The water-gas shift reaction is conducted in the presence of a catalyst. The carbon dioxide obtained by the water-gas shift reaction is reduced to generate carbon monoxide and oxygen. The separating the generated carbon dioxide and hydrogen further comprises separating with a hydrogen transfer membrane which comprises palladium, silica, copper, silver and/or their alloys. Preferred Components: The photocatalyst is: a titania supported platinum, palladium, ruthenium, rhodium and/or chromium; an oxide of tungsten, iron, titanium, zirconium, zinc, tantalum, niobium, vanadium, tin, lead, an alkali metal, and/or an alkali earth metal; a sulfide of zinc, gallium, indium, selenium and/or cadmium; a nitride of carbon, boron, gallium, germanium and/or tantalum; a partially nitrided-oxide; a partially sulfided-oxide; or a partially carbonized-oxide of tungsten, iron, titanium, zirconium, zinc, tantalum, niobium, vanadium, tin, lead, an alkali metal, an alkali earth metal, gallium and/or indium. The catalyst is: copper/zinc oxide/aluminum oxide composite catalyst; a titania supported platinum, palladium, ruthenium, rhodium, chromium and/or gold; and/or an oxide of supported tungsten, iron, titanium, zirconium, zinc, tantalum, niobium, vanadium, tin, lead, cerium, an alkali metal and/or an alkali earth metal. The fuel cell is a phosphoric acid fuel cell, a molten carbonate fuel cell, a solid oxide fuel cell, or a polymer electrolyte membrane fuel cell. EXAMPLE - Carbon dioxide was converted into carbon monoxide and oxygen using a lamp emitting light at 200-700 nm or sunlight in the presence of a photocatalyst (a titania supported platinum). Oxygen was separated using an oxygen transfer membrane (yttria stabilized zirconia membrane), and carbon monoxide and water were subjected to a water-gas shift reaction in the presence of a catalyst (copper/zinc oxide/aluminum oxide) to produce hydrogen and carbon dioxide. The hydrogen was separated using a hydrogen transfer membrane (comprising palladium) to obtain hydrogen.