Case studies on the formation of chalcogenide self-assembled monolayers on surfaces and dissociative processes

Abstract

SummaryThis report examines the assembly of chalcogenide organic molecules on various surfaces, focusing on cases when chemisorption is accompanied by carbon–chalcogen atom-bond scission. In the case of alkane and benzyl chalcogenides, this induces formation of a chalcogenized interface layer. This process can occur during the initial stages of adsorption and then, after passivation of the surface, molecular adsorption can proceed. The characteristics of the chalcogenized interface layer can be significantly different from the metal layer and can affect various properties such as electron conduction. For chalcogenophenes, the carbon–chalcogen atom-bond breaking can lead to opening of the ring and adsorption of an alkene chalcogenide. Such a disruption of the π-electron system affects charge transport along the chains. Awareness about these effects is of importance from the point of view of molecular electronics. We discuss some recent studies based on X-ray photoelectron spectroscopy that shed light on these aspects for a series of such organic molecules.

Enhanced Electrocatalytic Activity in GaSe and InSe Nanosheets: The Role of Surface Oxides

“…After one year in air, the area of the spectral contribution of Ga 2 O 3 in Ga‐3d core levels increased up to 53% of the total area and a new component associated to mixed oxide‐hydroxide Ga 2 O 3− x (OH) y species (10%) appeared at BE = 21.0 eV. [ 43 ] The corresponding analysis of Se‐3d core levels indicates a notable increase of the intensity of the spectral component at BE 54.6 eV and the emergence of a new feature at BE 55.2 eV, consistent with the formation of i) GaSe x O phases, having the same BE of Ga 2 Se 3, and ii) atomic Se(0) (24%) [ 44 ] as byproducts of GaSe and Ga 2 Se 3 oxidation via 3GaSe x +3/2 O 2 →3GaSe x O→ Ga 2 O 3 + GaSe + (3 x ‐1)Se and 2Ga 2 Se 3 + 3O 2 → 2Ga 2 O 3 + 6Se reactions. [ 35e ] Correspondingly, the gallium‐oxide skin reaches the thickness of 0.8 ± 0.1 nm, that is, ≈1.4 QL.…”

Se–C Cleavage of Hexane Selenol at Steps on Au(111)

“…For example, methane selenolate deposited on Au(111) from solution has been shown to result in atomic Se . The S–C dissociation process has also been studied previously; ,− preparation conditions and surface morphology as well as the presence of impurities were suggested as possible reasons for the chalcogenide–carbon bond dissociation. In this study, we report a combined photoelectron spectroscopy (PES), scanning tunneling microscopy (STM), and density functional theory (DFT) study of hexane selenol adsorption on Au(111).…”

“…They find technological use in controlling biocompatibility, corrosion resistivity, and tribology, and also in electronic devices, sensors, quantum dots, and photocatalysis. − The anchoring group, or atom, plays a crucial role in determining bond strength, electronic coupling, and charge flow between molecule and substrate . Thiols are commonly used for SAMs on coinage metals, − but selenols and tellurols have also obtained increasing interest . Studies on alkane thiolates and alkane selenolates on Au(111) show that the Se–Au bond is stronger than the S–Au bond.…”

III–VI and IV–VI van der Waals Semiconductors InSe, GaSe and GeSe: A Suitable Platform for Efficient Electrochemical Water Splitting, Photocatalysis and Chemical Sensing

“…Upon a prolonged exposure of one year in air, an increment of the spectral contribution of Ga 2 O 3 was revealed, with the appearance of a new component associated to mixed oxidehydroxide Ga 2 O 3-x (OH) y species. [84][85][86] No relevant changes exist in the Se-3d core level, in which a new component due to Se(0) and the component of SeÀ Se aggregates [87][88][89] as byproducts of Ga 2 Se 3 oxidation via 2Ga 2 Se 3 + 3O 2 !2Ga 2 O 3 + 6Se [74] was found. Accordingly, the thickness of gallium-oxide of about 0.8 nm was estimated.…”