title: Photocatalytic Hydrogen Generation Efficiencies in One-Dimensional CdSe Heterostructures.
abstract: To better understand the role nanoscale heterojunctions play in the photocatalytic generation of hydrogen, we have designed several model one-dimensional (1D) heterostructures based on CdSe nanowires (NWs). Specifically, CdSe/CdS core/shell NWs and Au nanoparticle (NP)-decorated core and core/shell NWs have been produced using facile solution chemistries. These systems enable us to explore sources for efficient charge separation and enhanced carrier lifetimes important to photocatalytic processes. We find that visible light H2 generation efficiencies in the produced hybrid 1D structures increase in the order CdSe < CdSe/Au NP < CdSe/CdS/Au NP < CdSe/CdS with a maximum H2 generation rate of 58.06 ± 3.59 μmol h(-1) g(-1) for CdSe/CdS core/shell NWs. This is 30 times larger than the activity of bare CdSe NWs. Using femtosecond transient differential absorption spectroscopy, we subsequently provide mechanistic insight into the role nanoscale heterojunctions play by directly monitoring charge flow and accumulation in these hybrid systems. In turn, we explain the observed trend in H2 generation rates with an important outcome being direct evidence for heterojunction-influenced charge transfer enhancements of relevant chemical reduction processes.
authors: †Department of Chemistry and Biochemistry, University of Notre Dame, 251 Nieuwland Science Hall, Notre Dame, Indiana 46556, United States.
authors: Pornthip
authors: P
authors: Tongying
authors: †Department of Chemistry and Biochemistry, University of Notre Dame, 251 Nieuwland Science Hall, Notre Dame, Indiana 46556, United States.
authors: Vladimir V
authors: VV
authors: Plashnitsa
authors: †Department of Chemistry and Biochemistry, University of Notre Dame, 251 Nieuwland Science Hall, Notre Dame, Indiana 46556, United States.
authors: Nattasamon
authors: N
authors: Petchsang
authors: †Department of Chemistry and Biochemistry, University of Notre Dame, 251 Nieuwland Science Hall, Notre Dame, Indiana 46556, United States.
authors: Felix
authors: F
authors: Vietmeyer
authors: ‡Notre Dame Radiation Laboratory, University of Notre Dame, 338 Radiation Research Building, Notre Dame, Indiana 46556, United States.
authors: Guillermo J
authors: GJ
authors: Ferraudi
authors: †Department of Chemistry and Biochemistry, University of Notre Dame, 251 Nieuwland Science Hall, Notre Dame, Indiana 46556, United States.
authors: Galyna
authors: G
authors: Krylova
authors: †Department of Chemistry and Biochemistry, University of Notre Dame, 251 Nieuwland Science Hall, Notre Dame, Indiana 46556, United States.
authors: Masaru
authors: M
authors: Kuno
keywords: Au; CdS; CdSe; charge separation; core/shell; heterojunction; hydrogen generation; nanoparticle; nanowire; photocatalysis