C60Br24/SWCNT: A Highly Sensitive Medium to Detect H2S via Inhomogeneous Carrier Doping

Jin Zhou,Mohammad Bagheri,Topias Järvinen,Hannu-Pekka Komsa,Cora Pravda Bartus,Akos Kukovecz,Krisztian Kordas

doi:10.1021/acsami.1c16807

Abstract

H2S is a toxic and corrosive gas, whose accurate detection at sub-ppm concentrations is of high practical importance in environmental, industrial, and health safety applications. Herein, we propose a chemiresistive sensor device that applies a composite of single-walled carbon nanotubes (SWCNTs) and brominated fullerene (C60Br24) as a sensing component, which is capable of detecting 50 ppb H2S even at room temperature with an excellent response of 1.75% in a selective manner. In contrast, a poor gas response of pristine C60-based composites was found in control measurements. The experimental results are complemented by density functional theory calculations showing that C60Br24 in contact with SWCNTs induces localized hole doping in the nanotubes, which is increased further when H2S adsorbs on C60Br24 but decreases in the regions, where direct adsorption of H2S on the nanotubes takes place due to electron doping from the analyte. Accordingly, the heterogeneous chemical environment in the composite results in spatial fluctuations of hole density upon gas adsorption, hence influencing carrier transport and thus giving rise to chemiresistive sensing.

Highlights

Hydrogen sulfide (H2S) is a corrosive, toxic, and colorless gas, which accompanies several industrial and natural processes, and may pose health risks upon extended exposure even at subppm concentrations
We report on nanocomposites of brominated fullerene (C60Br24) and single-walled carbon nanotubes (SWCNTs) as promising sensing media, which were immobilized on interdigital electrodes of chips using a simple brush-coating method to obtain chemiresistive sensor devices
The peaks at 1118 and 1224 cm−1 indicate the C−C−Br and C−C stretching vibrations, respectively.[34−36] In addition, compounding C60Br24 with SWCNTs does not seem to change the chemical structure according to the Fourier-transform infrared (FTIR) spectrum of C60Br24 in the C60Br24/SWCNT composite

Summary

INTRODUCTION

Hydrogen sulfide (H2S) is a corrosive, toxic, and colorless gas, which accompanies several industrial and natural processes, and may pose health risks upon extended exposure even at subppm concentrations. Weak interactions (e.g., by dispersion forces) generally accompany only small charge transfer between the sensing material and the analyte, which results in minute changes in the carrier concentration and a small sensory signal, often with good desorption and sensor recovery.[18−20] it is a plausible strategy to find a medium interaction strength between analytes and sensing materials to ensure optimal sensing performance of chemiresistive gas sensors. Low concentrations.[21−25] While semiconducting metal oxidebased sensors show good sensitivity, their typical major limitations are high operating temperatures and poor selectivity. Our study shows a feasible approach to sensitize CNTs with halogenated carbon nanomaterials having ideal properties for gas-sensing applications

RESULTS AND DISCUSSION

CONCLUSIONS

EXPERIMENTAL SECTION

■ ACKNOWLEDGMENTS

■ REFERENCES