A system and method is provided for using sunlight to convert an atmospheric gas to an output product and capture that output product. A photocatalytic element is encapsulated within a chamber in which the chamber is light transmissive, and is substantially permeable to the atmospheric gas and substantially impermeable to the output product. The photocatalytic element may be composed of a photocatalytic composition, comprising a first constituent capable of capturing or binding an atmospheric gas, a second constituent capable of reducing the atmospheric gas using energy from the sunlight, and a third constituent adapted to absorb sunlight, all combined into a single polymer. A fourth constituent may be added that is hydrophobic or hydrophilic depending upon the nature of the other three combined constituents.