Understanding unique orbital matching in graphene-supported single-atom sites for enhanced gas adsorption sensitivity

The understanding and prediction of the adsorption sensitivity of molecules in single-atom systems is an instructive and also challenging research topic. We here performed theoretical studies on interaction between isolated molecules and single transition-metal (TM) atoms in typical TM-N-C systems. This work demonstrates "unique orbital matching", e.g. CO/NO-2 & pi;* and TM-dxz,yz, or lone pair orbital of H2S/H2Se and TM-dz2, in determining adsorption mode. The charge transfer between adsorbents and substrate could be well described by orbital energy difference and shows a linear relationship with after adsorption local work function. Our studies could provide instructive guidance for efficient design of sensitive materials.