Kinetic Coupling of Water Splitting and Photoreforming on SrTiO3-Based Photocatalysts

Kai E. Sanwald, Tobias F. Berto, Andreas Jentys, Donald M. Camaioni, Oliver Y. Gutiérrez, Johannes A. Lercher

Research output: Contribution to journalArticlepeer-review

36 Scopus citations

Abstract

Coupling the proton reduction of overall water splitting with oxidation of oxygenated hydrocarbons (photoreforming) on Al-doped SrTiO3 decorated with cocatalysts enables efficient photocatalytic H2 generation along with oxygenate conversion, while decreasing the accumulation of harmful byproducts such as formaldehyde. Net H2 evolution rates result from the contributions of the individual rates of water oxidation, oxygenate oxidation, and the back-reaction of H2 and O2 to water. The latter reaction is suppressed by a RhCrOx cocatalyst or by high concentrations of oxygenates in the case of Rh cocatalyst, whereas the rates of organic oxidation depend on their molecular structure. In the absence of the back-reaction to water, the H2 evolution rates are independent of the oxygenate type and concentration because the rates of water splitting compensate the variations in the rates of oxygenate conversion. Under such conditions of suppressed back-reaction, the selectivities to water and oxygenate oxidation, both occurring with the same quantum efficiencies, depend on the oxygenate type and concentration. The dominant pathways for organic transformations are ascribed to the action of intermediates generated at the semiconductor during water oxidation and O2 evolution. On a semiconductor without cocatalyst, the O2 produced during overall water splitting is reductively activated to participate in oxidation of organics without consuming evolved H2.

Original languageEnglish
Pages (from-to)2902-2913
Number of pages12
JournalACS Catalysis
Volume8
Issue number4
DOIs
StatePublished - 6 Apr 2018

Keywords

  • Photocatalysis
  • SrTiO
  • glycerol
  • oxidation mechanism
  • photoreforming
  • water splitting

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