Room-Temperature Hydrogen Sensor with High Sensitivity and Selectivity using Chemically Immobilized Monolayer Single-Walled Carbon Nanotubes

Abstract

Although semiconducting single-walled carbon nanotubes (sc-SWNTs) exhibit excellent sensing properties for various gases, commercialization is hampered by several obstacles. Among these, the difficulty in reproducibly fabricating sc-SWNT films with uniform density and thickness is the main one. Here, a facile fabrication method for sc-SWNT-based hydrogen (H-2) sensors with excellent reproducibility, high sensitivity, and selectivity against CO, CO2, and CH4 is reported. Uniform-density and monolayer sc-SWNT films are fabricated using chemical immobilized through the click reaction between azide-functionalized polymer-wrapped sc-SWNTs and immobilized alkyne polymer on a substrate before decorating with Pd nanoparticles (0.5-3.0 nm). The optimized sc-SWNT sensor has a high room-temperature response of 285 with the response and recovery times of 10 and 3 s, respectively, under 1% H-2 gas in air. In particular, this sensor demonstrates highly selective H-2 detection at room temperature (25 degrees C), compared to other gases and humidity. Therefore, the chemical immobilization of the monolayer SWNT films with reproducible and uniform density has the potential for large-scale fabrication of robust room-temperature H-2 sensors.