Sensitive H2S gas sensors employing colloidal zinc oxide quantum dots

Colloidal quantum dots (CQDs), due to the excellent solution processability, low cost and ease of integration, are emerging as promising candidates for gas sensors. Here, colloidal zinc oxide quantum dots were synthesized through a simple colloidal method with oleic acid (OA) as the surface-capping ligand. The well dispersed ZnO CQDs were spin-coated onto ceramic substrates to construct chemiresistive gas sensors. The film-level ligand exchange treatment was applied to remove the long-chain surface-capping which thereby facilitated efficient gas adsorption and carrier transport. The optimal sensor exhibited the best performance with a response of 113.5 upon 50 ppm of H2S exposure at room temperature, with a fast response time being 16s. The obtained results suggested that ZnO CQDs are promising materials candidate for high-performance gas sensors.