(201e) Synthesis of TiO2 Nanoparticles Modified by Transition Metals for Solar Fuel Production From CO2 and Water

Titanium dioxide (TiO2) nanoparticles modified by transition metals (Ag, Cu) have been synthesized through a one-step, low-cost spray pyrolysis method in this study. A BGI Colison Nebulizer was used to atomize the precursor solution consisting of TTIP, ethanol, silver nitrate/copper nitrate, and acetic acid. The precursor aerosols were delivered to a quartz reactor inside a tubular furnace where the Ag/Cu-TiO2 composite particles were produced and collected. The materials were characterized by XRD, UV-vis diffuse reflectance, SEM, TEM, etc. The particle size, crystal phase, optical behavior, and silver dispersion were correlated with precursor composition, furnace temperature, and residence time. The Ag/Cu-TiO2 nanoparticles were tested as photocatalysts for two renewable fuel applications: (1) hydrogen production from photocatalytic water splitting and (2) CO2 photoreduction with water for production of fuels (CO, methane, or methanol, etc), both under solar irradiation. A 450 W Xe lamp and a 150 W Solar Simulator with AM 1.5G filter were used as the light sources. A Gas Chromatograph (GC) equipped with TCD/FID/MS detectors was used to identify the products and measure the yields of solar fuels.  The activities of catalysts with different Ag/Cu concentrations and TiO2 particle sizes were investigated and compared with benchmark Ag/Cu-P25 catalysts prepared by incipient wet-impregnation method.