One-pot hydrothermal growth of indium oxide-CNT heterostructure via single walled carbon nanotube scaffolds and their application toward flexible NO2 gas sensors

Single walled carbon nanotubes (SWNTs) are recognized as a promising sensing material for flexible NO 2 gas sensors, whereas poor recovery at room temperature is a significant barrier to practical application. This study reports a one-pot hydrothermal synthesis of an indium oxide/single-walled carbon nanotube heterostructure (h-In 2 O 3 /SWNT) for efficient recovery in gas sensors. This results in the stable formation of 2-dimensional electron gases and their favorable electron compensation in the channel layers. The h-In 2 O 3 /SWNT FET gas sensors (h-GS) exhibit a sensing resolution of 1 ppm, negligible degradation over 9 consecutive cycled exposures with a 2-day-interval, and a significant improvement in recovery within 10 min at room temperature. Surprisingly, even when the flexible h-GS is evaluated under repeated tensile strain of 0.88 %, electrical reliability and reproducibility of the h-GS is fully validated. Thus, with its demonstrated robust sensing properties and compensation scheme, the h-In 2 O 3 /SWNT is expected to be a promising candidate for use as a novel sensing layer in a wearable gas sensor, resolving one of the long-standing issues associated with gas sensor sluggish recovery and reliability for impact. • One-pot hydrothermal synthesis of indium oxide/carbon nanotube heterostructure (h-In2O3/SWNT). • NO2 gas sensors based on three-terminal h-In2O3/SWNT transistors on rigid and flexible substrates. • Enhanced NO2 recovery via efficient electron compensation of a two-dimensional (2D) electron gas. • Sensing capability for NO2 gas at a concentration of 1 ppm at room temperature. • Reliability with negligible degradation over 9 consecutive cycled exposures with a 2-day-interval.