Boron-Doped ZrS2 Monolayer as a Promising Gas Sensing Material for the Detection of Volatile Organic Compounds: A DFT Study

Detecting volatile organic compounds (VOCs) with high sensitivity and selectivity is essential for environmental monitoring and health protection. This study employs first-principles calculations to explore the structural, electronic, and adsorption properties of pristine and boron-doped ZrS2 (B-ZrS2) monolayers toward key VOCs: formaldehyde (CH2O), methanol (CH3OH), acetaldehyde (CH3CHO), and acetone (C3H6O). Boron atoms stably incorporate at hollow sites, forming strong covalent B–S bonds and significantly narrowing the band gap from 0.861 eV to 0.091 eV. Pristine ZrS2 exhibits weak physisorption and minimal charge transfer with VOCs, limiting sensing capability. In contrast, B doping creates chemically active sites that promote chemisorption through B–O bond formation and enhanced charge transfer. Density of states analyses reveal strong electronic coupling between adsorbates and the B-ZrS2 surface, causing notable electronic structure changes. Frontier molecular orbital theory shows that VOC adsorption increases the band gap, reducing electrical conductivity and modulating the sensor signal. Calculated sensitivities indicate that B-ZrS2 responds effectively to all four VOCs at room temperature, especially methanol, with rapid recovery facilitated by temperature-dependent desorption kinetics. Additionally, B-ZrS2 shows weak interactions with common atmospheric gases (N2, O2, CO2, H2O), ensuring selectivity and stable sensor performance under realistic conditions. Overall, these results demonstrate that B-ZrS2 is a promising, sensitive, selective, and thermally adaptable resistive-type gas sensor for environmental VOCs detection.