Pd4 cluster decorated SnO2 nanowire for detecting characteristic gases in oil-immersed transformers: A theoretical and experimental study

The adsorption behaviors, electronic properties and gas-sensing performances of Pd 4 cluster decorated SnO 2 nanowire to H 2 and C 2 H 2 suggest that Pd 4 -SnO 2 is a promising gas-sensing material for detecting characteristic gases in oil-immersed transformers. • The Pd 4 cluster decorated SnO 2 nanowire is first proposed as a promising gassensing material for detecting characteristic gases in oil-immersed transformers. • The introduction of Pd 4 cluster can not only improve the conductivity of the intrinsic SnO 2 , but also provide more active sites for gas adsorption. • The Pd cluster decorated SnO 2 nanocomposites were successfully synthesized via electrospinning technology along with magnetron sputtering process. • Both the theoretical calculation and experimental testing results indicate that the gas sensitivity of intrinsic SnO 2 is greatly enhanced after Pd cluster modification. In this paper, Pd 4 cluster decorated SnO 2 (Pd 4 -SnO 2 ) nanowire is considered as a novel gas sensor alternative for detecting the typical dissolved gases in transformer oil, including hydrogen (H 2 ) and acetylene (C 2 H 2 ). Specifically, the most stable geometric structures of gas molecules, Pd 4 -SnO 2 and gases adsorbed by Pd 4 -SnO 2 are systematically explored via the density functional theory (DFT) method. The geometric structure formation, density of states (DOS), deformation charge density (DCD) and molecular orbital theory analysis are used to reveal the gas adsorption and sensing mechanism. Simulation calculation results show that Pd 4 cluster modification can significantly enhance the gas-sensitive response of intrinsic SnO 2 , Pd atoms which provide active sites for gas adsorption owing to their outstanding metallic and catalytic behaviors. It also offers excellent adsorption capacity for both gas molecules. Meanwhile, the Pd cluster decorated SnO 2 sensing materials are successfully synthesized by electrospinning technology combined with magnetron sputtering process. The micromorphology structure of the synthesized samples are analyzed by using SEM and other microscopic techniques. The gas-sensing investigations indicate that this composite nanomaterial could be a potential candidate for gas-sensing applications. The testing data shows high consistency to the simulation conclusion and the results in this work can be applied to produce and promote Pd cluster decorated SnO 2 gas sensors, ultimately realizing online monitoring of oil-immersed transformers.