Electronic Structure of Metal (M = Au, Pt, Pd, or Ru) Bilayer Modified α-Fe₂O₃(0001) Surfaces

Abstract

Metal modified metal oxides are promising and economical catalysts for important processes such as CO oxidation and the partial oxidation of methanol. The present work is to investigate, by density functional theory, the electronic and geometric structures of metal (M = Au, Pt, Pd, or Ru) bilayer modified R-Fe 2 O 3 (0001) catalysts, focusing on the synergistic effect at the interface between the metal bilayer and R-Fe 2 O 3 (0001) support and its connection with its catalytic activity. It is found that the synergistic effect is largely dependent on the localized electron gain, electron transfer from Fe atoms to the dz 2 orbitals of the metal bilayer, and interfacial metallic/ionic bonding. Such synergistic effect is most pronounced for R-Fe 2 O 3 catalysts modified with the Pt or Ru bilayer. The Au bilayer modified R-Fe 2 O 3 catalyst is the most stable due to the low structural deformation of R-Fe 2 O 3 support, minimal surface Fe atom spin quenching, and long Au-Fe bonds. The R-Fe 2 O 3 catalyst modified with Ru bilayer displays the optimal balance of the synergistic effect and structural stability that can enhance catalytic activity.

Driven translocation of semiflexible polyelectrolyte through a nanopore

“…[11][12][13][14] The duration time for DNA chains passing through a nanopore is usually named as translocation time τ. In experiments, it was found that the translocation time can be governed by modifying the interactions between DNA chain and nanopore, 15,16 or changing the size of nanopore. 11,17 The translocation time is dependent on many factors such as polymer-pore interaction, [18][19][20] the solvent property, [21][22][23][24][25] pore size, 26 polymer-surface interaction, 27,28 chaperones and nanoparticles at the trans side.…”

Investigating the effect of mono‐ and multivalent counterions on the conformation of poly(styrenesulfonic acid) by nanopores

“…Translocation of NaPSS has been studied by several groups before [33][34][35]. In order to reduce the complexity in signal events [32], we chose a relatively short NaPSS sample (M w = 4300, M w /M n = 1.2) for translocation studies.…”

“…In principle, nanopores are also highly suitable for studying synthetic polyelectrolytes because they can also translocate through nanopores resembling DNA molecules. However, due to the molecular mass polydiversity and complicated sidechain structures of polyelectrolytes, only moderate successes have been achieved with nanopore sensors [32][33][34][35][36]. In this report, we propose to use a protein nanopore, ␣-hemolysin (␣HL), to investigate the effect of mono-and multivalent counterions on the conformational changes of a simple polyelectrolyte, sodium poly(styrenesulfonic acid) (NaPSS).…”

Theoretical study on the translocation of partially charged polymers through nanopore

“…9 Since the first experiment on the translocation of DNA chain through a-hemolysin protein nanopores in 1996, 1 nanoporebased DNA sequencing has attracted increasing interest and great progress has been made during the last two decades. [10][11][12][13][14][15][16][17] The ionic current across protein nanopores or solid nanopores is reduced significantly when a polymer chain is inside the nanopore. 1,10,11,14 From the drop of the ionic current, one can measure the translocation time of a chain through nanopore.…”

“…[10][11][12][13][14][15][16][17] The ionic current across protein nanopores or solid nanopores is reduced significantly when a polymer chain is inside the nanopore. 1,10,11,14 From the drop of the ionic current, one can measure the translocation time of a chain through nanopore. 1 It was found that the level and shape of ionic current and the translocation time were dependent on the detailed information of DNA/RNA molecules when they were driven through the nanopore under external electrical potential.…”