Single Pd atom embedded Janus HfSeTe as promising sensor for dissolved gas detection in transformer oil: A density functional theory study

Exploring high-performance sensing materials aimed at dissolved gases in transformer oil is of crucial importance to guarantee the safe and stable operation of power transformer. This study investigates the adsorption and sensing of five kinds of dissolved gas molecules (H2, CO, CH4, C2H2, and C2H4) on single Pd atom doped Janus HfSeTe monolayer (Pd-HfSeTe). The adsorption structure, adsorption energy, electron transfers, density of states (DOS), band structure, and work function are calculated. The results demonstrate that single Pd atom has much larger binding energy on HfSeTe surface compared to bulk Pd, and shows high thermal stability at 500 K. In addition, the doping of Pd significantly enhances the adsorption strength of CO, C2H2, and C2H4. The electronic properties illustrate that the band gap experiences apparent increase for CO adsorption on Pd site for both Se and Te surface, and there shows obvious overlapping of Pd 4d and C 2p orbitals in atomic DOS for CO, C2H2, and C2H4 adsorption. Furthermore, taking electronic properties, work function, and occupation function into consideration, Pd-HfSeTe can detect C2H4 with higher selectivity as both resistance-type and work-function type gas sensor. This theoretical study allows novel opinions of Janus transitional-metal dichalcogenides (TMDCs) doped with single transition-metal atom as sensing materials for gas detection in numerous application area.