title: Simple Growth of Faceted Au-ZnO Hetero-nanostructures on Silicon Substrates (Nanowires and Triangular Nanoflakes): A Shape and Defect Driven Enhanced Photocatalytic Performance under Visible Light.
abstract: A simple single-step chemical vapor deposition (CVD) method has been used to grow the faceted Au-ZnO hetero-nanostructures (HNs) either with nanowires (NWs) or with triangular nanoflakes (TNFs) on crystalline silicon wafers with varying oxygen defect density in ZnO nanostructures. This work reports on the use of these nanostructures on substrates for photodegradation of rhodamine B (RhB) dyes and phenol under the visible light illumination. The photoluminescence measurements showed a substantial enhancement in the ratio of defect emission to band-edge emission for TNF (ratio ≈ 7) compared to NW structures (ratio ≤ 0.4), attributed to the presence of more oxygen defects in TNF sample. The TNF structures showed 1 order of magnitude enhancement in photocurrent density and an order of magnitude less charge-transfer resistance (R(ct)) compared to NWs resulting high-performance photocatalytic activity. The TNFs show enhanced photocatalytic performance compared to NWs. The observed rate constant for RhB degradation with TNF samples is 0.0305 min(-1), which is ≈5.3 times higher compared to NWs case with 0.0058 min(-1). A comparison has been made with bulk ZnO powders and ZnO nanostructures without Au to deduce the effect of plasmonic nanoparticles (Au) and the shape of ZnO in photocatalytic performance. The results reveal the enhanced photocatalytic capability for the triangular nanoflakes of ZnO toward RhB degradation with good reusability that can be attracted for practical applications.
authors.affiliation: †Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005, India.
authors.forename: Arnab
authors.initials: A
authors.lastname: Ghosh
authors.affiliation: †Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005, India.
authors.forename: Puspendu
authors.initials: P
authors.lastname: Guha
authors.affiliation: ‡CSIR-Institute of Minerals and Materials Technology, Bhubaneswar 751013, India.
authors.forename: Aneeya K
authors.initials: AK
authors.lastname: Samantara
authors.affiliation: ‡CSIR-Institute of Minerals and Materials Technology, Bhubaneswar 751013, India.
authors.forename: Bikash Kumar
authors.initials: BK
authors.lastname: Jena
authors.forename: Rajshekhar
authors.initials: R
authors.lastname: Bar
authors.forename: Samit K
authors.initials: SK
authors.lastname: Ray
authors.forename: Samit
authors.initials: S
authors.lastname: Ray
authors.affiliation: †Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005, India.
authors.forename: Parlapalli V
authors.initials: PV
authors.lastname: Satyam
keywords: dye degradation; hetero-nanostructures; oxygen defects; photocatalyst; photoelectrochemistry; triangular nanoflakes