Topological insulators (TIs) are expected to realize new spintronic devices with low dissipative electrical transport. Organic molecule/TI interfaces have been investigated to explore the potential of multifunctional organic molecules for TI devices. However, there is no unified understanding of the interfacial electronic structure. The electronic structure of the molecular side must be examined to fully understand the phenomena at the interface. Thus, this paper reports the investigation of the interface between the electron‐donating organic molecule tetrathianaphthacene (TTN) and prototypical TI Bi2Se3 by ultraviolet photoemission spectroscopy (UPS), X‐ray photoemission spectroscopy (XPS), and angle‐resolved photoemission spectroscopy (ARPES). The deformation of the Fermi surface of the topological surface states as well as the formation of a 2D electron gas state (2DEG) at the interface occurs upon TTN deposition onto Bi2Se3. Confinement of the 2DEG into the surface arises from band‐bending accompanied by electron donation from TTNs to Bi2Se3 according to XPS and UPS. The knowledge obtained in this work shed new light on the understanding of the electronic structure of organic molecules/TI interfaces and open the door to the TI applications via modification by electronic functional organic molecules.

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Recently, the interface between an organic molecular layer and a topological insulator (TI) surface (Org./TI interface) has been studied to explore the possibility of multifunctional TI devices with organic molecules. Nevertheless, understanding of the electronic structure of Org./TI interfaces is insufficient. Especially, little is known about physisorption systems, where the interaction between adsorbed molecules and topological surface state (TSS) is weak. Here, we discuss an ideal physisorption system of an n-alkane molecule, n-tetratertacontane (TTC), and prototypical TI, Bi 2 Se 3 , in which the interaction between the molecule and TSS is the weakest one possible. Angle-resolved photo-emission spectroscopy results show that the energy of the Dirac cone (DC) energy band decreases by approximately 60 meV when the TTC layer is formed on Bi 2 Se 3 . The amount of energy reduction is consistent with the reduction in vacuum level at the TTC/Bi 2 Se 3 interface, valence states of Bi 2 Se 3 and the core levels of Bi 2 Se 3 observed by ultravioletand X-ray photoemission spectroscopy. Therefore, no chemical interactions, such as charge transfer, occur at the TTC/ Bi 2 Se 3 interface, but only a redistribution of charge density on the Bi 2 Se 3 surface occurs due to the Pauli repulsion between the electrons of the adsorbed TTC molecule and TSS.

To simulate the corrosion of galvanized steel in a marine zone, steel rust of β-FeOOH particles was prepared by aerial oxidation of aqueous FeCl 2 solutions containing ZnCl 2 and zinc rusts such as ZnO and zinc hydroxychloride (Zn 5 (OH) 8 Cl 2 3 H 2 O, ZHC). The crystallinity and particle size of β-FeOOH were slightly decreased by adding the ZnCl 2 . The produced particles contained a small amount of ZnCl 2 , while the zinc rusts of ZnO and ZHC markedly impeded the crystallization and particle growth of β-FeOOH. In the presence of a large amount of zinc rusts, the formation of β-FeOOH was suppressed and γ-FeOOH and ZHC of which the particle size was larger than that of β-FeOOH were generated. The inhibitory effect on the formation of β-FeOOH was on order of ZHC ≈ ZnO . ZnCl 2 . The effect of zinc rusts was ascribed to the increment of solution pH by dissolution of rust particles and adsorption of Zn(II) on a precursor of β-FeOOH particles. The adsorption of CO 2 on the products was also suppressed by the addition of ZnCl 2 and zinc rusts. These results imply that the β-FeOOH rust formed on galvanized steel in a marine environment is more compact, leading to improved corrosion resistance. However, existence of a large amount of zinc rust particles inhibits the formation of a compact rust layer and lowers the ability for corrosion resistance.