Proton exchange membrane electrolysis using water vapor as a feedstock

A method of generating a chemical fuel and molecular oxygen from a reaction medium containing water vapor, comprising the steps of:

• providing an illumination-driven apparatus, comprising:
• a separator having a first side and a second side opposite said first side, said separator configured to be permeable to an ionic reaction moiety and configured to be substantially impermeable to molecular moieties so as to separate a first molecular moiety present on said first side from a second molecular moiety present on said second side;
• an oxidation catalyst present on said first side of said separator, said oxidation catalyst configured to oxidize H2O to produce molecular oxygen;
• a reduction catalyst present on said second side of said separator, said reduction catalyst configured to reduce a substance to produce a chemical fuel;
• a source of water vapor, said water vapor permitted to contact said first side of said separator and said oxidation catalyst;
• and
• a light absorber configured to absorb illumination, configured to provide electrons at a voltage sufficient to drive a desired chemical half-reaction at said reduction catalyst, and configured to accept electrons so as to drive another desired chemical half-reaction at said oxidation catalyst, said light absorber and said separator in mechanical contact so as to form a monolithic structure;
• providing water vapor that contacts said first side of said separator and said oxidation catalyst;
• illuminating said light absorber;
• oxidizing H2O to molecular oxygen at said oxidation catalyst;
• permitting H+ ions to permeate said separator;
• and
• performing a reduction at said reduction catalyst to produce a chemical fuel comprising hydrogen.