Anodic titania nanotubes decorated with gold nanoparticles produced by laser-induced dewetting of thin metallic films

Katarzyna Grochowska,Łukasz Haryński,Nikolay Nedyalkov,Gerard Śliwiński,Katarzyna Siuzdak,Jakub Karczewski

doi:10.1038/s41598-020-77710-x

Abstract

Herein, we combine titania layers with gold species in a laser-supported process and report a substantial change of properties of the resulting heterostructures depending on the major processing parameters. Electrodes were fabricated via an anodisation process complemented with calcination to ensure a crystalline phase, and followed by magnetron sputtering of metallic films. The obtained TiO2 nanotubes with deposited thin (5, 10 nm) Au films were treated with a UV laser (355 nm) to form Au nanoparticles on top of the nanotubes. It was proven that selected laser working parameters ensure not only the formation of Au nanoparticles, but also simultaneously provide preservation of the initial tubular architecture, while above-threshold laser fluences result in partial destruction (melting) of the top layer of the nanotubes. For almost all of the samples, the crystalline phase of the nanotubes observed in Raman spectra was maintained independently of the laser processing parameters. Enhanced photoresponse up to ca 6 mA/cm2 was demonstrated by photoelectrochemical measurements on samples obtained by laser annealing of the 10 nm Au coating on a titania support. Moreover, a Mott–Schottky analysis indicated the dramatically increased (two orders of magnitude) concentration of donor density in the case of a laser-treated Au–TiO2 heterojunction compared to reference electrodes.

Highlights

We combine titania layers with gold species in a laser-supported process and report a substantial change of properties of the resulting heterostructures depending on the major processing parameters
A facile and rapid method of Au-coated titanium dioxide nanotubes modification which leads to enhancement of the photoactivity of the studied material is presented. TiO2NTs were formed in an optimised anodisation process which was further followed by calcination in a furnace to ensure an anatase crystalline phase
The optical studies indicated that laser processing is causing the narrowing of the energy bandgap, which is of key importance for future applications in solar-driven processes

Summary

Introduction

We combine titania layers with gold species in a laser-supported process and report a substantial change of properties of the resulting heterostructures depending on the major processing parameters. A change of the anodisation voltage, electrolyte composition, namely the water and fluorine ion content, and the whole process duration allow the geometric parameters of the tubular structure to be controlled: their length, internal diameter, wall thickness, and even the distance between particular tubes[15] Since such a wide range of different NT morphologies can be provided, titania nanotubes remain a very interesting substrate especially once decorated with. As thermal treatment realised in continuous mode—typically in a furnace—is time-consuming and includes heating and cooling periods, laser irradiation may be used to form the nanoparticles out of thin film Such processing is used for flat substrates[26,27] and, to the best of our knowledge, has not been applied until now to fabricate Au–TiO2 materials of a high degree of ordering. The obtained results enable nomination of the fabricated electrode material with enhanced photoactivity towards successful water splitting process

Methods

Results

Conclusion