Keio University · Materials Science
Professor Hiroshi Kondoh's research lab specializes in surface science and materials chemistry, focusing on the atomic-scale structure, growth mechanisms, and surface reactions of self-assembled monolayers, particularly alkanethiols on noble and transition metal surfaces. The lab employs advanced surface characterization techniques such as scanning tunneling microscopy (STM), X-ray absorption fine structure (XAFS) spectroscopy, and photoelectron spectroscopy under ultrahigh- and ambient-pressure conditions to investigate molecule–substrate interactions, phase transitions, and catalytic reactions. A key research direction involves understanding the coverage-dependent desorption behavior and structural evolution of thiolate monolayers, as well as the role of surface electronic states in catalytic processes such as oxygen evolution and NO reduction. The lab also explores functional oxide interfaces for photoelectrochemical applications, emphasizing in situ probing of oxidation states and reaction dynamics.
Figures are computed from collected data and may differ slightly.
The adsorption structure of methylthiolate (CH3S) adsorbed on Au(111), a long-standing controversial issue, has been unambiguously determined by scanned-energy and scanned-angle S 2p photoelectron diffraction. The methylthiolate molecules are found to occupy atop sites with a S-Au distance of 2.42 +/- 0.03 A. The angular distribution of the S 2p photoelectrons due to forward scattering reveals that the S-C bond is inclined by approximately 50 degrees from the surface normal towards both the [211
The adsorption and desorption of n-alkanethiol monolayers on Au(111) have been studied under ultrahigh-vacuum condition by the use of scanning tunneling microscopy (STM), thermal desorption spectroscopy (TDS), and Auger electron spectroscopy (AES). Molecularly resolved STM observations for the alkanethiol monolayers have revealed that at least four different phases evolve during growth, which results in a multistep growth of the monolayer. The desorption species drastically changes at a critical
The coverage dependence of desorption behavior of n-alkanethiol monolayers on Au(111) has been studied using thermal desorption spectroscopy (TDS) together with scanning tunneling microscopy (STM) to investigate the molecule−substrate interactions. STM observations indicated four different phases during the growth. We present for the first time evidence for a drastic coverage-dependent change of desorption species, which is parallel with a structure change from a low-density phase to a denser ph
We have studied the structure and growth process of hexanethiolate self-assembled monolayers (SAMs) on Cu(100) by means of scanning tunneling microscopy (STM) and X-ray absorption fine structure (XAFS) spectroscopy. At saturated coverage, the thiolates are assembled into a c(2 × 6) structure with zigzag chains along the close-packed Cu rows. The sulfur atom of the thiolate occupies the 4-fold hollow site of the unreconstructed Cu(100) surface with a nearest-neighbor S−S distance of 3.6 Å. Such s
The Mn-oxide/Nb:SrTiO3 photoelectrode for oxygen evolution reaction was investigated by in situ Mn K-edge XAFS spectroscopy under UV irradiation. The oxidization of the Mn oxide was observed via photoexcited carrier transfer, which results in the positive potential shift of the Mn oxide cocatalyst toward oxygen evolution reaction.
NO reduction by CO on Rh(111) was investigated by near-ambient pressure X-ray photoelectron spectroscopy, mass spectrometry, and kinetic analysis. Under exposure to NO + CO mixed gases and with heating the surface from room temperature to 450 °C, NO dissociation and NO reduction reaction start simultaneously independent of gas pressure ratio of NO/CO, which indicates that NO dissociation triggers this reaction. From kinetic analyses based on observed adsorbate coverages under reaction conditions
Low-temperature phases of methylthiolate (CH3S) monolayers on Au(111) have been investigated by using cryogenic scanning tunneling microscopy. The methylthiolate monolayers have a structure with a ( × )R30° lattice at room temperature, while at 110 K it is transformed into a one-dimensional “chain structure” near step edges and a two-dimensionally ordered structure with an anisotropic lattice on terraces. The latter structure has an oblique commensurate (3 × 4) unit cell (8.6 × 11.5 Å) in which
Effects of electron irradiation on a methylthiolate (CH3S) self-assembled monolayer on Au(111) have been studied by using scanning tunneling microscope (STM), Auger electron spectroscopy (AES), low-energy electron diffraction, and thermal-desorption spectroscopy (TDS). AES results indicated that irradiation of the CH3S/Au(111) surface by an electron beam induces electron-stimulated desorption (ESD), in which mainly the methyl moiety desorbs via S−C bond cleavage, leaving a sulfur atom on the sur
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