Enhanced NH₃ and NO₂ Sensing via Pd Decoration on WSeTe Janus Monolayers: A DFT Investigation

Abstract This study uses first‐principles calculation to investigate the potential of palladium (Pd)‐decorated single‐layer WSeTe (Pd‐WSeTe) as high‐performance gas sensors for NH₃ and NO₂. The impact of Pd placement (SeWTe‐T H , SeWTe‐T Se , SeWTe‐T W , TeWSe‐T H , TeWSe‐T Te , and TeWSe‐T W ) is quantified on WSeTe's electronic properties, focusing on the changes in bandgap (ΔEg). Pd decoration significantly alters the bandgap, with SeWTe‐T H exhibiting a drastic reduction (0.115 eV) compared to pristine WSeTe (1.335 eV). This substantial ΔEg reduction in SeWTe‐T H suggests a potential enhancement in sensor response. Furthermore, SeWTe‐T Se displays the strongest binding capacity for targeted gases NH₃ and NO₂. SeWTe‐T Se exhibits adsorption energy of −1.693 eV (NO₂) and −1.517 eV (NH₃), indicating its enhanced sensitivity and exceptional NO₂ sensing capability. These results show that the performance of gas sensing is much improved by Pd decoration, especially along SeWTe‐T Se (NO₂). This makes the Pd‐WSeTe Janus monolayer a highly sensitive and selective gas sensor that may be used for several tasks, such as breath analysis, leak detection, and environmental monitoring.