Remarkable variation of visible light photocatalytic activities of M/Sn0.9Sb0.1O2/TiO2 (M=Au, Ag, Pt) heterostructures depending on the loaded metals

Abstract

Sn_0.9Sb_0.1O₂/TiO₂ (ATO/TiO₂) heterostructure is a potential visible light photocatalysts that function via an inter-semiconductor hole-transport mechanism. Herein we selectively deposited Au, Ag, or Pt onto the ATO surface of ATO/TiO₂ to investigate charge-trapping behaviors of the noble metals and their effects on photocatalytic performance. We observed that Pt deposition greatly enhanced the photocatalytic activity whereas effects of Au or Ag depositions were not significant. The result of spectroscopic analysis also indicates that Pt is the most effective in scavenging the electrons from the ATO CB. Particularly, Pt/ATO/TiO₂ (ATO:TiO₂ = 15:85 in weight) produced CO₂ of 42 ppmv in 2 h, which is 16 times and 4.8 times that of bare ATO/TiO₂ and nitrogen-doped TiO₂, respectively. Pt deposition on the ATO seems to suppress two independent charge recombination pathways, that is, recombination of electron-hole pairs in ATO and electron transport from the ATO CB to TiO₂ VB.

Keywords: Heterojunction of semiconductors; Hole transport; Noble metal; Sn(1-x)Sb(x)O(2)/TiO(2); Visible light photocatalyst.