Electronic Transport in Porous Nanocrystals Enables Ultrasensitive Consistent Detection of Sulfur Dioxide under...

The growing release of gaseous pollutants, such as sulfur dioxide (SO₂), underscores the need for widely distributed monitoring and reliable electronic sensing platforms capable of detecting trace concentrations of such contaminants under real-world conditions. However, achieving high sensitivity and selectivity, while maintaining stable, reproducible sensing performance with conductive materials, particularly under fluctuating humidity, remains a significant challenge. This work reports a highly crystalline, conductive tetrapyrazinoporphyrazine (TPz)-based metal-organic framework (MOF), DC-103, featuring cobalt-centered TPz ligands and copper bis(dioxolene) linkages. DC-103 exhibits rapid, robust, and humidity-resistant chemiresistive responses toward SO₂ across diverse environments. Notably, DC-103 outperforms previously reported MOF-based SO₂ sensors, achieving a limit of detection as low as 2.2 parts-per-billion (ppb) in air and maintaining consistent, reversible responses across 0-98% relative humidity levels. Furthermore, the sensor demonstrates excellent reusability in humid air, retaining consistent responses upon repeated exposures. Spectroscopic and computational analyses revealed distinct material-analyte interactions and redox changes of MOF components and sulfurous species under dry or humid nitrogen or air atmospheres. Collectively, these findings establish DC-103 as a robust chemiresistive sensor for SO₂, with superior performance compared to structurally analogous or control structures, demonstrating applicability across diverse atmospheric conditions, and offering significant potential in occupational safety and environmental monitoring.