Silicone microreactors for the photocatalytic generation of hydrogen

• Silicone microreactors are manufactured with PDMS and molds with a 3D printer.
• Au/TiO2 photocatalyst is immobilized over the silicone microchannel walls.
• Ethanol-water mixtures and bioethanol are tested for H2 photo production.
• Optimum H2 yields obtained with 1.2 mgphotocat cm−2 and UV irradiance of 1.5 mW cm−2.

A silicone microreactor with 500 μm-width microchannels coated with a Au/TiO2 photocatalyst was manufactured and tested for the photocatalytic generation of hydrogen from gaseous water-ethanol mixtures under dynamic conditions. The manufacture of the microreactor included the fabrication of a polylactic acid (PLA) mold with a 3D printer and casting with polydimethylsiloxane (PDMS) prepolymer. After curing, the silicone microreactor was peeled off and the microchannels were coated with a Au/TiO2 photocatalyst prepared by impregnation of preformed Au nanoparticles over TiO2, and sealed with a thin silicone cover. The microreactor was tested at room temperature and atmospheric pressure under different operational conditions (photon irradiance, residence time, photocatalyst loading, and water-ethanol ratio). Hydrogen production rates of 5.4 NmL W−1 h−1 were measured at a residence time of 0.35 s using a H2O:C2H5OH molar ratio of 9:1, a photocatalyst load of 1.2 mg cm−2 and a UV irradiance (365 nm) of 1.5 mW cm−2 achieving an apparent quantum efficiency of 9.2%. The photogeneration of hydrogen with commercial bioethanol was also tested. A long-term photocatalytic test of two days revealed a stable hydrogen photoproduction rate. The use of silicone microreactors represents an attractive and customizable solution for conducting photochemical reactions for producing hydrogen at low cost.

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