The aim of the work discussed in this paper was to characterize adsorbed self-assembled monolayers on different metal oxide substrates with angle-resolved XPS measurements. The substrates used were silicon wafers (100) coated with 300 nm Al, Ta, or Ti. They were coated with acids by immersing them in an ethanol solution. The orientation of long-chain organic acids adsorbed on metal oxides has been successfully identified by angle-resolved XPS. On Al, Ta, and Ti substrates, C(11) chains are orientated in the right manner, i.e. with the phosphonic group at the bottom and the thiophene group on top. The orientations of the C(2) and C(6) chains are not clear. The thickness of the layers could be obtained by using Tougaard nanostructure analysis, and it shows monolayers. A model of the chemical bonds between the phosphonic group and the metal could be developed from the chemical shift. For titanium, all three P-O bonds bind to the metal substrate, whereas only the P-O(H) bond binds to the metal on aluminium and tantalum.
A P doped MoO nanocomposite material with rich oxygen vacancies is successfully fabricated by a two-step intercalation method, which presents superior activity for the hydrogen evolution reaction with low overpotential and fast electron transfer. In 0.5 m H SO , it displays an overpotential of 166 mV for driving the current density of 10 mA cm . Moreover, it also shows a good catalytic stability in the electrolytes with different pH, 0.5 m H SO (strong acid), 0.5 m Na SO (neutral solution), and 0.1 m NaOH (strong base). The superior catalytic activity and stability are due to to the synergistic effect between the P element doping and the oxygen vacancies.
It
was found for the first time that the existence of hindrance
units of sodium p-styrenesulfonate (SSS) on the polymer
backbone could increase the hydrophobic content of the polymers on
the premise of water solubility. A novel series of brush-like amphiphilic
statistical tripolymers were designed and prepared by polymerization
of amphiphilic macromonomer 2-(acrylamido)-dodecane sulfonic acid
(AMC12S, 10 to 90 mole fraction), with SSS (0 to 5 mole
fraction), and 2-(acrylamido)-2-methylpropanesulfonic acid (AMPS).
The self-assembly behaviors of these tripolymers were investigated
using a combination of steady-state fluorescence, dynamic light scattering
(DLS), and transmission electron micrograph (TEM) methods, mainly
focusing on the effect of varying unit contents along the polymer
backbone on the associative performance. The increase of amphiphilic
units results in a simultaneous decrease of the microdomain polarity
and the assembly size. Furthermore, the increase of hindrance units
leads to an increase of assembly size but no change of microdomain
polarity, manifesting a further aggregation of the polymer assemblies.
The further aggregation partly results from the stretch facilitation
of polymer chains by the hindrance units, and the facilitation effect
works more intensely for the polymers with less amphiphilic units.
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