Enhanced Methanol Dissociation on Nanostructured 2D Al Overlayers

Abstract

Three well-defined two-dimensional (2D) Al overlayers including the Al/Si(111) α-phase with Al coverage of ∼0.25 ML, the Al/Si(111) γ-phase with Al coverage of ∼0.8 ML, and the bulk Al film with Al coverage of 16 ML on Si(111) have been prepared using the molecular beam epitaxy technique. Their surface morphology and electronic structure were characterized by scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), and ultraviolet photoelectron spectroscopy (UPS). The 16 ML Al film presents the metallic Al character, while the nanostructured Al/Si(111) α-phase and γ-phase are semiconducting due to space confinement of the surface Al atoms. The interfacial Al−Si interaction results in electron deficiency in surface Al atoms which follows the order of Al/Si(111) α-phase > Al/Si(111) γ-phase > bulk Al film. Methanol dissociation reactions on the Al surfaces at room temperature were studied by XPS and high-resolution electron energy loss spectroscopy (HREELS). The Al/Si(111) α-phase presents the highest activity for the dissociation of CH3OH and CH3Oads and the lowest activity for the bulk Al film. The exceptional activity of the nanostructured 2D Al surfaces for O−H and C−O bond scission has been attributed to their unique geometric structures as well as their semiconducting and electron-deficient characters.

Redox Protein-Polymer Films for Simultaneous Determination of Ascorbic Acid and Hydrogen Peroxide

“…Many techniques involving enzymes have been investigated for hydrogen peroxide determination. 12,[19][20][21] In glucose sensing, hydrogen peroxide is a product of glucose oxidase metabolism of glucose in un-mediated systems. In blood, ascorbic acid is usually an interfering agent during glucose sensing.…”

Unique Reactivity of Confined Metal Atoms on a Silicon Substrate

“…An SiA C H T U N G T R E N N U N G (111) surface is an ideal template for the growth of various quantumconfined metal nanostructures, for example, 2D quantum-well films and 0D quantum dots. [5,6] Particularly, Ag deposited on Si-…”

Functionalization of gold surfaces with copoly(DMA-NAS-MAPS) by dip coating: Surface characterization and hybridization tests

“…The main peak (A 1 ) is located at 285.6 eV and represents about 63% of the entire C1s signal. As it can be ascribed both to adventitious carbon (carbon partially bounded to O and N [25]) and C C bonds, it cannot be unambiguously [ [26][27][28] The experimental weight of A 2 and A 3 are 22% and 15% of the whole C1s peak, respectively, but also in this case they can be only partially attributed to C atoms within the polymer, due to some possible CO and CO 2 contaminations contributing to A 2 and A 3 . These values must be compared with the polymer chemical structure, from which the relative weight of the different carbon bonds can be evaluated.…”

“…Regarding oxygen, three features give rise to the O1s peak, but here the attribution is not straightforward. While the feature at 531.7 eV (C 1 ) is due only to NC O groups [26], the prominent contribution at 533.3 eV (C 2 ) can arise from the overlap of the signals from H 2 O (533.3 eV), O CH 3 (533.2 eV) [28] and C O (533.6 eV) groups [30]. The minor feature at 534.9 eV (C 3 ) might instead be due to physisorbed CO 2 .…”