[1Fp01-09] Surface Science(SS2) Chemical Property

[1Fp09] Operando spectroscopic identification of reactive electron species for photocatalytic hydrogen evolution on metal-loaded oxide surfaces

*Hiromasa Sato¹, Toshiki Sugimoto^1,2 (1. Department of Materials Molecular Science, Institute for Molecular Science, 2. Graduate Institute for Advanced Studies, SOKENDAI)

Identification of reactive carriers on photocatalysts provides a firm framework for rational design of catalysts. Here, using operando IR spectroscopy under periodic modulation of excitation light intensity, we succeeded in identifying the reactive electrons for photocatalytic H₂ evolution on Pt- or Pd-loaded Ga₂O₃ particulate catalysts exposed to methane gas and water vapor. We demonstrated that the only band intensity derived from electrons trapped at the in-gap state ~0.26 eV below the conduction band minimum of Ga₂O₃ changed in clear response to the enhancement of H₂ formation rate among the several observed bands attributed to various electron species. This indicates that the trapped electrons in Ga₂O₃ directly contribute to H₂ evolution instead of electrons in metal cocatalysts. Furthermore, capacity of the reactive electrons was drastically changed between Pt/Ga₂O₃ and Pd/Ga₂O₃, suggesting that these reactive states are localized at the periphery of metal cocatalysts.