Compact Integration of TiO₂ Nanoparticles into the Cross-Points of 3D Vertically Stacked Ag Nanowires for Plasmon-Enhanced Photocatalysis.

Vo Thi Nhat Linh,Yong-Ill Lee,Sung-Gyu Park,Dong-Ho Kim,Vincenzo Giannini,Xiaofei Xiao,Stefan A Maier,Ho Sang Jung

doi:10.3390/nano9030468

Abstract

The compact integration of semiconductor TiO2 nanoparticles (NPs) into the 3D crossed region of stacked plasmonic Ag nanowires (NWs) enhanced the photocatalytic activities through synergistic effects between the strong localized surface plasmon resonance (LSPR) excitation at the 3D cross-points of the Ag NWs and the efficient hot electron transfer at the interface between the Ag NWs and the TiO2 NPs. This paper explored new hybrid nanostructures based on the selective assembly of TiO2 NPs onto 3D cross-points of vertically stacked Ag NWs. The assembled TiO2 NPs directly contacted the 3D Ag NWs; therefore, charge separation occurred efficiently at the interface between the Ag NWs and the TiO2 NPs. The composite nanomaterials exhibited high extinction across the ultraviolet-visible range, rendering the nanomaterials high-performance photocatalysts across the full (ultraviolet-visible) and the visible spectral regions. Theoretical simulations clearly revealed that the local plasmonic field was highly enhanced at the 3D crossed regions of the vertically stacked Ag NWs. A Raman spectroscopic analysis of probe dye molecules under photodegradation conditions clearly revealed that the nanogap in the 3D crossed region was crucial for facilitating plasmon-enhanced photocatalysis and plasmon-enhanced spectroscopy.

Highlights

Semiconductor photocatalysts have been widely investigated for use in environmental science and technology applications, especially toward the degradation of organic pollutants [1,2,3,4], the photocatalytic production of hydrogen [5,6,7], and the photocatalytic reduction of carbon dioxide [8,9,10]
The compact hybrid nanostructures embedded on glass microfiber filter would be separated from treated solution, which can be applied in water treatment [24,25]
We proposed the use of new composite nanomaterial into which TiO2 NPs were compactly integrated into the 3D cross-points of vertically stacked Ag NWs for plasmon-enhanced photocatalysis

Summary

Introduction

Semiconductor photocatalysts have been widely investigated for use in environmental science and technology applications, especially toward the degradation of organic pollutants [1,2,3,4], the photocatalytic production of hydrogen [5,6,7], and the photocatalytic reduction of carbon dioxide [8,9,10]. Conventional semiconductor photocatalysts exhibit poor photocatalytic performances under visible light illumination (λ > 400 nm) due to their wide band gaps. Titanium dioxide (TiO2) in the crystalline anatase phase has a band gap of 3.2 eV (λ = 388 nm), and TiO2 semiconductor nanomaterials are active under ultraviolet (UV) light (over only 7.5% of the full solar spectrum). At the LSPR excitation, plasmonic nanostructures can absorb and concentrate visible light at nanoscale gaps (hot spots) between metallic nanostructures, and highly energetic hot electrons can be injected into nearby TiO2 NPs. As a result of this plasmonic sensitization process, a wide band gap TiO2 material that is inactive under visible light can become active under visible light [11,12,13,14,15,16,17]

Methods

Results

Conclusion