(600bc) Porous Microsphere Composites of Silver/Ceria/Titania for Solar Fuel Production

Photocatalytic conversion of carbon dioxide and water to fuels using low-cost and stable photocatalysts like titanium dioxide (TiO₂) is a promising sustainable energy technology that not only reduces greenhouse gas emissions but also produces renewable fuels. However, the fast recombination of photo-induced electron-hole pairs results in a very low CO₂ reduction efficiency. In this work, we have synthesized porous microsphere composites of nanocrystalline TiO₂ modified with silver (Ag) and/or  ceria (CeO₂). The TiO₂ nanocrystals of anatase and anatase-brookite mixed phase as well as Ce-doped TiO₂ were first fabricated by a hydrothermal method. Subsequently, Ag/TiO₂ or Ag/Ce/TiO₂ porous microspheres were synthesized through an ultrasonic spray pyrolysis (USP) process.  The photocatalytic activity of the prepared photocatalysts was tested in a photoreactor system under simulated sunlight irradiation.  It was demonstrated that synthetic gas or syngas, a mixture of hydrogen (H₂) and carbon monoxide (CO) could be successfully produced from the photocatalytic conversion of CO₂ and water in the presence of methanol as the hole scavenger.  The H₂/CO ratio in the produced syngas was correlated with the photocatalyst properties.