The first-principles study on electronic transport mechanism in palladium decorated graphene for inert gas sensing

Abstract

Inert gases, despite various uses and industrial applications, may cause asphyxiation, so their detection and monitoring are essentially needed. However, the preparation of inert gas sensors is challenging due to the inactive chemical nature of these gases. This work was carried out to investigate the transport properties of inert gas sensors based on palladium-clusters-decoratedgraphene-sheets (Pd-Gr) using Density Functional Theory (DFT) based methodology. The sensors comprising Pd clusters Pdn (n = 2-5) decorated graphene were simulated to investigate the structural stability, adsorption, sensitivity, and electronic characteristics. The transport properties were studied using current-voltage (I-V) curves obtained via non-equilibrium Green's function (NEGF). The current appeared small at the start due to higher electrical resistance caused by charge transfer due to the adsorption of inert gases on the sensors. However, a voltage-dependent increase in the current took place afterward. The values of the resistance are found sensitive to the adsorption of the inert gases onto the sensors which helped to detect the gases. The energy difference of frontier molecular orbitals contributing to the conduction exhibited different responsive voltages which helped to points to the gas being adsorbed on the sensor. The findings of the work revealed that Pd2 sensors are sensitive towards xenon and neon, Pd3 and Pd4 are suitable for the detection of krypton and helium respectively whereas the Pd5 sensor is more appropriate for sensing argon and radon gases.