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 |ΔEg| 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.