Rh and Ir-Doped PtS₂ Monolayers as Promising Sensors for Liver Disease Biomarker Detection in Exhaled Breath: A First-Principles Study

The detection of biomarkers in exhaled breath offers an efficient approach for the early-stage identification of liver disease. In this work, first-principles calculations were employed to investigate the adsorption and sensing properties of Rh- and Ir-decorated PtS₂ monolayers toward four liver disease biomarkers (LDBs: C₂H₆O, C₃H₈O, C₃H₆O, and C₅H₈). The results reveal that pristine PtS₂ exhibits a low affinity for these biomarkers, whereas single-atom decoration with Rh or Ir significantly enhances both adsorption energy and charge transfer. These interactions were further elucidated through analyses of projected density of states, total electron density, charge density difference, and charge transfer. Furthermore, the adsorption of all four LDBs results in |Δ<i>E</i> _g| exceeding 16.57%, except for the C₃H₆O/Rh@PtS₂ system. Notably, the adsorption of C₅H₈ and C₃H₈O induces a pronounced semiconductor-to-metal transition in Rh@PtS₂ and Ir@PtS₂ systems, respectively. Crucially, both Rh@PtS₂ and Ir@PtS₂ show excellent selectivity, exhibiting significantly higher adsorption strengths for the target LDBs compared to common interfering molecules present in exhaled breath (H₂O, N₂, CO₂, and CH₄). Additionally, Rh@PtS₂ exhibits a suitable recovery time (τ) of 22.7 s at 298 K for C₂H₆O, along with moderate τ values of 0.27 s (C₂H₆O) and 3.94 s (C₃H₆O) at 348 K. Consequently, Rh@PtS₂ emerges as a promising reversible sensor material for the detection of C₂H₆O and C₃H₆O. This study provides a strategic blueprint for developing PtS₂-based gas sensor applications for the medical field.