Ultrafast spectroscopy demonstrates that charge transfer can occur between photoexcited inorganic semiconductors and metal-organic frameworks (MOFs), supplying long-lifetime electrons for the reduction of gas molecules adsorbed on the MOF. As a proof of concept, a unique method is developed for synthesizing Cu-3(BTC)(2)@TiO2 core-shell structures with macroporous semiconductor shells that allow gas molecules to be captured in the cores.