Hemin-functionalized InAs-based high sensitivity room temperature NO gas sensors
We investigate the chemistry and kinetics of the surface functionalization of InAs with hemin aimed at demonstrating novel hemin-functionalized InAs planar resistors or molecularly controlled resistors (MOCSERs) with subparts per billion sensitivity to NO at 300 K. The high performance is a result of the strong coupling of the intrinsic surface-confined two-dimensional electron gas (2DEG) at the InAs surface with the surface-attached hemin molecules and their selective interactions with NO. The presence of the surface 2DEG in InAs is highly advantageous for sensing and obviates the need for high surface area to volume geometries conferred by nanowire structures. The chemistry and kinetics of surface attachment processes are investigated using X-ray photoelectron spectroscopy, atomic force microscopy, and spectroscopic ellipsometry, showing that the covalent attachment of hemin to both In and As sites modifies the band-bending of the InAs. In addition, the selective, reversible electronic interaction between hemin and NO molecules increases the InAs resistance, reducing the NO during the interaction. In addition to presenting the sensor performance characteristics, a chemical model based on the electron transfer from the 2DEG of InAs to the iron center of hemin, which reduces Fe(III) to the higher NO affinity Fe(II) state, is proposed. © 2011 American Chemical Society.
Dedigama, A; Angelo, M; Torrione, P; Kim, TH; Wolter, S; Lampert, W; Atewologun, A; Edirisoorya, M; Collins, L; Kuech, TF; Losurdo, M; Bruno, G; Brown, A
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