Au sputter-deposited ZnO nanofibers with enhanced NO2 gas response

Abstract

A selective NO2 gas sensor was fabricated using Au-decorated ZnO nanofibers. A layer of Au was sputter-deposited on the synthesized ZnO nanofibers. The thicknesses of the Au layers were varied as 3, 6, 9, 12, and 15 nm for optimization. Annealing of the samples at a high temperature converted the Au layer to isolated Au nanoparticle (NPs) dispersed on the ZnO nanofibers. Different characterizations including structural, chemical, and morphological confirmed that the composition and morphology of the Au-decorated ZnO nanofibers were appropriate for gas sensing. The sensor with an Au layer thickness of 9 nm demonstrated an optimal response at 350 °C. The enhanced sensing response stemmed from the optimal amount of Au, generation of Au–ZnO Schottky junctions, and catalytic effect of Au NPs. This study highlights the need for the optimization of the amount of Au NPs to achieve improved response to a target gas.