Evaluation of gas-sensing properties of ZnO nanostructures electrochemically doped with Au nanophases.

Elena Dilonardo,Marco Alvisi,Nicola Cioffi,Michele Penza,Cinzia Di Franco,Luisa Torsi,Francesco Palmisano

doi:10.3762/bjnano.7.3

Abstract

A one-step electrochemical method based on sacrificial anode electrolysis (SAE) was used to deposit stabilized gold nanoparticles (Au NPs) directly on the surface of nanostructured ZnO powders, previously synthesized through a sol–gel process. The effect of thermal annealing temperatures (300 and 550 °C) on chemical, morphological, and structural properties of pristine and Au-doped ZnO nancomposites (Au@ZnO) was investigated. Transmission and scanning electron microscopy (TEM and SEM), as well as X-ray photoelectron spectroscopy (XPS), revealed the successful deposition of nanoscale gold on the surface of spherical and rod-like ZnO nanostructures, obtained after annealing at 300 and 550 °C, respectively. The pristine ZnO and Au@ZnO nanocomposites are proposed as active layer in chemiresistive gas sensors for low-cost processing. Gas-sensing measurements towards NO2 were collected at 300 °C, evaluating not only the Au-doping effect, but also the influence of the different ZnO nanostructures on the gas-sensing properties.

Highlights

Today the use of low-cost portable gas sensors is essential to detect and to monitor toxic, polluting and combustible gases for the environmental protection
It is influenced by the surface area and by the presence of structural defects and impurities that positively affect the gas detection. It is favored by the presence of oxygen species adsorbed on metal oxide semiconductors (MOS) surface, whose amount strongly depends on MOS morphology and structure, and on the gaseous analyte [4]
The surface chemical composition of pristine and Au-doped ZnO nanocomposites annealed at 300 and at 550 °C was obtained by X-ray photoelectron spectroscopy (XPS) analysis

Summary

Introduction

Today the use of low-cost portable gas sensors is essential to detect and to monitor toxic, polluting and combustible gases for the environmental protection. The second function transduces the solid–gas interaction into the electrical resistance variation of the gas sensor, correlated to the adsorbed gas concentration to be detected; it is influenced by the morphological structures of the MOs active layer and by the interface between sensing material and metal electrodes of the device [5].

Results

Conclusion