title: Photocatalytic reduction of carbon dioxide over Ag cocatalyst-loaded ALa4Ti4O15 (A = Ca, Sr, and Ba) using water as a reducing reagent.
abstract: Ag cocatalyst-loaded ALa(4)Ti(4)O(15) (A = Ca, Sr, and Ba) photocatalysts with 3.79-3.85 eV of band gaps and layered perovskite structures showed activities for CO(2) reduction to form CO and HCOOH by bubbling CO(2) gas into the aqueous suspension of the photocatalyst powder without any sacrificial reagents. Ag cocatalyst-loaded BaLa(4)Ti(4)O(15) was the most active photocatalyst. A liquid-phase chemical reduction method was better than impregnation and in situ photodeposition methods for the loading of the Ag cocatalyst. The Ag cocatalyst prepared by the liquid-phase chemical reduction method was loaded as fine particles with the size smaller than 10 nm on the edge of the BaLa(4)Ti(4)O(15) photocatalyst powder with a plate shape during the CO(2) reduction. CO was the main reduction product rather than H(2) even in an aqueous medium on the optimized Ag/BaLa(4)Ti(4)O(15) photocatalyst. Evolution of O(2) in a stoichiometric ratio (H(2)+CO:O(2) = 2:1 in a molar ratio) indicated that water was consumed as a reducing reagent (an electron donor) for the CO(2) reduction. Thus, an uphill reaction of CO(2) reduction accompanied with water oxidation was achieved using the Ag/BaLa(4)Ti(4)O(15) photocatalyst.
authors.affiliation: Department of Applied Chemistry, Faculty of Science, Research Institute of Science and Technology, Tokyo University of Science, 1-3 Kagurazaka, Tokyo 162-8601, Japan.
authors.forename: Kosuke
authors.initials: K
authors.lastname: Iizuka
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Wato
authors.forename: Yugo
authors.initials: Y
authors.lastname: Miseki
authors.forename: Kenji
authors.initials: K
authors.lastname: Saito
authors.forename: Akihiko
authors.initials: A
authors.lastname: Kudo
mesh_terms: D001464:Barium / Q000737:chemistry; D017610:Calcium Compounds / Q000737:chemistry; D002245:Carbon Dioxide / Q000737:chemistry*; D002248:Carbon Monoxide / Q000737:chemistry; D002384:Catalysis; D005561:Formates / Q000737:chemistry; D007811:Lanthanum / Q000737:chemistry; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry; D055668:Photochemical Processes; D019163:Reducing Agents / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry; D014867:Water / Q000737:chemistry*
chemical_list: D017610:Calcium Compounds; D005561:Formates; D010087:Oxides; D019163:Reducing Agents; D014867:Water; C030544:formic acid; C059910:perovskite; D002245:Carbon Dioxide; D001464:Barium; D012834:Silver; D007811:Lanthanum; D002248:Carbon Monoxide; D014025:Titanium; D010100:Oxygen