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

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 (H₂) 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% H₂ gas in air. In particular, this sensor demonstrates highly selective H₂ detection at room temperature (25 °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 H₂ sensors.