H₂S sensing for breath analysis with Au functionalized ZnO nanowires

Abstract

This work presents a H2S selective resistive gas sensor design based on a chemical field effect transistor (ChemFET) with open gate formed by hundreds of high temperature chemical vapour deposition (CVD) grown zinc oxide nanowires (ZnO NW). The sensing ability of pristine ZnO NWs and surface functionalized ZnO NWs for H2S is analysed systematically. ZnO NWs are functionalized by deposition of discontinuous gold (Au) nanoparticle films of different thicknesses of catalyst layer ranging from 1 to 10 nm and are compared in their gas sensing properties. All experiments were performed in a temperature stabilized small volume compartment with adjustable gas mixture at room temperature. The results allow for a well-founded understanding of signal-to-noise ratio, enhanced response, and improved limit of detection due to the Au functionalisation. Comprehension and controlled application of the beneficial effects of Au catalyst on ZnO NWs allow for the detection of very low H2S concentrations down to 10 ppb, and a theoretically estimated 500 ppt in synthetic air at room temperature.

Advances in Noble Metal-Decorated Metal Oxide Nanomaterials for Chemiresistive Gas Sensors: Overview

“…1D nanostructures such as nanorods [ 211 ] and nanowires [ 212 ] are believed to be able to facilitate reaction between materials and target gas molecules and thus improve the gas sensing performance of Au-decorated ZnO gas sensors [ 213 ]. Guo et al [ 214 ] successfully fabricated Au-functionalized ZnO nanorods gas sensor for ethanol detecting.…”

1D and 2D Field Effect Transistors in Gas Sensing: A Comprehensive Review

“…Concerning 1D‐FETs, MOXNWs represent one of the least expensive 1D materials, also robust at high operation temperatures, with diameter and length tunable with several bottom‐up fabrication technologies. Among others, SnO 2 , [ 65–72 ] ZnO, [ 73–84 ] and In 2 O 3 [ 85–95 ] (and in some cases Fe 2 O 3 [ 96 ] and CuO [ 97,98 ] ) have been used in the manufacturing of (mostly) single NW 1D‐FET (Figure 33a) gas sensors and several approaches have been successfully adopted to control the sensing performance (i.e., sensitivity and selectivity) of MOXNW‐FETs, among which, physical functionalization with metal (i.e., Au, [ 92,93 ] Ag, [ 93 ] Pd, [ 69 ] and Pt [ 93 ] ) and semiconducting (i.e., ZnO and NiO [ 71 ] ) NPs (Figure 34a), temperature and gate voltage driving, [ 72 ] fabrication of Ohmic or Schottky junctions at the MOXNW‐metal contact interfaces. [ 91 ] However, the need of high operation temperatures typical of bulk MOX has been only partially solved using ZnO, [ 73,75,82 ] In 2 O 3 , [ 85,86,88,90–95 ] and Fe 2 O 3 [ 96 ] NWs, which strongly limits applications of MOXNW‐FETs in low‐power low‐energy electronic applications.…”

Breath Analysis: A Promising Tool for Disease Diagnosis—The Role of Sensors

“…Selective H 2 S detection has been also attempted using Au-decorated SWCNTs, leading to high Au NPs size-dependent sensitivity and lower LOD (≤100 ppb) in comparison to carboxylated SWCNTs ( Figure 8 ) [ 156 ]. A lower LOD of 10 ppb and a theoretical LOD of 500 ppt for selective H 2 S detection have been recently achieved using a FET based on Au NPs-functionalized ZnO NWs [ 157 ]. Au NPs of 1, 3, 5, 7, and 10 nm were tested, with those of 7 nm leading to the maximum interaction between the analyte and the sensing film.…”