Effect of Catalysis-clustering on Gas-sensing Performance*

We present a theoretical investigation, based on a combined of density-functional theory (DFT) and non-equilibrium Green’s-functional (NEGF) formalism, to study the effect of catalysis-clustering on the sensor response. Specifically, the scope is to compare the adsorption and transport properties after chemisorption of CO₂ molecules on iron (Fe) ad-atoms deposited on graphene nano-ribbons (GNR) in two different ways: (i) Five Fe ad-atoms deposited on GNR in scattered fashion; and (ii) A cluster of five Fe atoms deposited on GNR. The results of IV-curves calculations confirm stronger deviations in the case of scattered Fe ad-atoms and, consequently, stronger sensor response. This work suggests stronger sensitivity and selectivity to be reached by scattering ad-atoms of the transition-metal catalysis and with an optimization of their density. As the sensor response is based on the deviation of conductance from before to after the exposure to the gas, our results have indeed a direct application to fabricate solid-state based gas sensors working with high sensitivity at room temperature, to detect toxic and hazardous gases such as CO₂.