Single-Ru-Doped PtSe₂ Monolayer with Superior Adsorption and Sensing Performance over Au for HCHO, C₆H₆, and Rn Monitoring: A First-Principles Investigation

The long-term preservation of historical documents in archival environments is critically challenged by the accumulation of hazardous gases—formaldehyde (HCHO), benzene (C₆H₆), and radon (Rn)—which originate from collection materials and pose severe health risks to personnel. In this work, we systematically investigate, via first-principles theory, the potential of Au- and Ru-doped PtSe₂ monolayers as resistive-type gas sensors for the detection of these pollutants. Atomic-scale substitutional doping at the Se site is modeled to establish the doped PtSe₂ configurations, and the structural stability, electronic properties, adsorption behavior, charge transfer characteristics, and recovery kinetics of the doped systems are comprehensively evaluated and compared. Our findings, through comprehensive comparison, reveal that Ru-PtSe₂ outperforms its Au-doped counterpart across all key performance metrics, positioning it as a promising candidate for hazardous gas monitoring in archival environments. The key innovation of this work lies in the systematic comparative assessment of noble metal dopants on PtSe₂ monolayers, identifying Ru as a superior choice to Au and providing a theoretical foundation for designing high-performance, recyclable 2D material-based gas sensors tailored for cultural heritage preservation applications.