Tailoring Pd-Doped MoS2Monolayers for Enhanced Hydrogen Sulfide Gas Sensing

Abstract

In this study, high-quality pristine and 2.5% Pddoped monolayer MoS2 films were synthesized using a customdesigned 12-zone chemical vapor deposition (CVD) system employing liquid precursors. The synthesis was carried out on SiO2/Si substrates using a precursor solution of MoO3 dissolved in NH4OH and NaCl. The monolayers were subsequently transferred onto interdigitated electrode (IDE) devices via a surface energyassisted wet transfer method that leverages the contrasting hydrophilic and hydrophobic nature of MoS2 and SiO2. Gas sensing performance was evaluated for both pristine and doped samples. While the pristine MoS2 exhibited a moderate response of 47% to H2S at room temperature, the 2.5% Pd-doped monolayer demonstrated a significantly enhanced response of 176%, with rapid response and recovery times of 55.6 s and 85.2 s, respectively. The sensor maintained stable performance under high humidity conditions, low gas concentrations down to 1 ppm, and across 8 continuous sensing cycles. Repeatability and reproducibility were verified across four separate devices, all yielding consistent results. © 2025 IEEE.