Significant Enhancement of NO₂ Detection Response in MoTe₂ Nanostructures with a 1T′-2H Structure Mixture

Abstract

Due to their high surface-to-volume ratio and material structure, two-dimensional transition-metal dichalcogenides (TMDs) exhibit excellent characteristics on gas sensors. NO 2 detection was investigated in the liquid-phase exfoliated MoTe 2 nanoparticle cluster with different 2H to 1T′ component ratios. These ratios were controlled via thermal annealing processes at different temperatures. The detection response was found to be sensitive to the 2H to 1T′ component ratios. The response was measured to be 0.2% at 25 ppb from the 2H structure, but no detection response was taken from the 1T′ structure. The response was then enhanced by two orders through an appropriate 2H and 1T′ structural mixture and was higher than most reported values in two-dimensional transition-metal dichalcogenides under similar conditions. This enhancement originates from reducing effective contact resistance from the metallic 1T′ structure and carrier contribution from the semiconducting 2H structure.