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Preparation and Reaction Studies of Pt / Al₂O₃ Model Catalysts
Changmin Kim,Gabor A. Somorjai 한국진공학회(ASCT) 1994 Applied Science and Convergence Technology Vol.3 No.4
알루미늄 박편 위에 Pt/Al₂O₃ 모델 촉매를 만들었다. 알루미늄 표면을 10^(-5)Torr의 산소 압력 하에서 산화시킨 후, plasma evaporation source를 사용하여 Pt을 증착시켰다. 이 모델 촉매 표면에서 얼어나는 1-butene의 반응을 연구하였다. 산화알루미늄 표면에서는 이성질화 반응이 일어났으나, Pt을 증착시킨 산화알루미늄 표면에서는 수소첨가반응이 일어남이 관찰되었다. 알루미나 표면의 Pt이 증가함에 따라 수소첨가반응으로의 선택성이 증가되었다. Surface of Pt/Al₂O₃ model catalyst was produced on an aluminum foil with surface area of 1 ㎠. The aluminum surface was oxidized under 10^(-5) Torr oxygen and platinum was deposited on top of the oxide layer using a plasma evaporation source. Conversion of 1-butene was performed on the model catalyst surface. Isomerization was the major reaction in 1-butene conversion on the aluminum oxide layer. Addition of Pt on the aluminum oxide layer induces hydrogenation of 1-butene. Selectivity for the hydrogenation increases as the amount of Pt on alumina increases.
Kim, Il-Kwang,Somorjai, Gabor A,Kim, Youn-Geun Korean Chemical Society 1991 Bulletin of the Korean Chemical Society Vol.12 No.1
The preparation and characterization of semiconductive electrodes of MgO doped $Fe_2O_3$ were investigated. Pellets of MgO doped $Fe_2O_3$ were sintered at high temperatures between 1300$^{\circ}$C and 1400$^{\circ}$C and quenched rapidly in distilled water. The surfaces were analyzed by X-ray diffraction and scanning Auger electron spectroscopy. The surfaces of pellets contained both corundum structure ($Fe_2O_3$) and spinel structure ($Mg_xFe_{3-x}O_4$). Electrodes made of this material gave comparable anodic and cathodic photocurrents under illumination. The cathodic and anodic photocurrent on these photoelectrodes were verified high at 5-10 wt. percent that is critical doping amounts.
Kim, Il Kwang,Gabor A. Somorjai,Kim, Youn Geun 원광대학교기초자연과학연구소 1992 基礎科學硏究誌 Vol.11 No.3
The preparation and characterization of semiconductive electndes of MgO doped Fe₂O₃ were investigated. Pellets of MgO doped Fe₂O₃ were sintered at high temperatures between 1300℃ and 1400℃ and quenched rapidly in distilled water. The surfaces were analyzed by X-ray diffraction and scanning Auger electron spectroscopy. The surfaces of pellets contained both corundum structure(Fe₂O₃) and spinel structure(Mg, Fe₂, O₄). Electrodes made of this material gave comparable anodic and cathodic photocurrents under illumination. The cathodic and anodic photocurrent on these photoelectrodes were verified high at 5-10 wt. percent that is critical doping amounts.
Choi, Kyung Min,Na, Kyungsu,Somorjai, Gabor A.,Yaghi, Omar M. American Chemical Society 2015 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.137 No.24
<P>Chemical environment control of the metal nanoparticles (NPs) embedded in nanocrystalline metal–organic frameworks (nMOFs) is useful in controlling the activity and selectivity of catalytic reactions. In this report, organic linkers with two functional groups, sulfonic acid (−SO<SUB>3</SUB>H, S) and ammonium (−NH<SUB>3</SUB><SUP>+</SUP>, N), are chosen as strong and weak acidic functionalities, respectively, and then incorporated into a MOF [Zr<SUB>6</SUB>O<SUB>4</SUB>(OH)<SUB>4</SUB>(BDC)<SUB>6</SUB> (BDC = 1,4-benzenedicarboxylate), termed UiO-66] separately or together in the presence of 2.5 nm Pt NPs to build a series of Pt NPs-embedded in UiO-66 (Pt⊂nUiO-66). We find that these chemical functionalities play a critical role in product selectivity and activity in the gas-phase conversion of methylcyclopentane (MCP) to acyclic isomer, olefins, cyclohexane, and benzene. Pt⊂nUiO-66-S gives the highest selectivity to C<SUB>6</SUB>-cyclic products (62.4% and 28.6% for cyclohexane and benzene, respectively) without acyclic isomers products. Moreover, its catalytic activity was doubled relative to the nonfunctionalized Pt⊂nUiO-66. In contrast, Pt⊂nUiO-66-N decreases selectivity for C<SUB>6</SUB>-cyclic products to <50% while increases the acyclic isomer selectivity to 38.6%. Interestingly, the Pt⊂nUiO-66-SN containing both functional groups gave different product selectivity than their constituents; no cyclohexane was produced, while benzene was the dominant product with olefins and acyclic isomers as minor products. All Pt⊂nUiO-66 catalysts with different functionalities remain intact and maintain their crystal structure, morphology, and chemical functionalities without catalytic deactivation after reactions over 8 h.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2015/jacsat.2015.137.issue-24/jacs.5b03540/production/images/medium/ja-2015-035409_0001.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja5b03540'>ACS Electronic Supporting Info</A></P>
Surface Plasmon-Driven Hot Electron Flow Probed with Metal-Semiconductor Nanodiodes
Lee, Young Keun,Jung, Chan Ho,Park, Jonghyurk,Seo, Hyungtak,Somorjai, Gabor A.,Park, Jeong Young American Chemical Society 2011 Nano letters Vol.11 No.10
<P>A continuous flow of hot electrons that are not at thermal equilibrium with the surrounding metal atoms is generated by the absorption of photons. Here we show that hot electron flow generated on a gold thin film by photon absorption (or internal photoemission) is amplified by localized surface plasmon resonance. This was achieved by direct measurement of photocurrent on a chemically modified gold thin film of metal-semiconductor (TiO<SUB>2</SUB>) Schottky diodes. The short-circuit photocurrent obtained with low-energy photons is consistent with Fowler’s law, confirming the presence of hot electron flows. The morphology of the metal thin film was modified to a connected gold island structure after heating such that it exhibits surface plasmon. Photocurrent and optical measurements on the connected island structures revealed the presence of a localized surface plasmon at 550 ± 20 nm. The results indicate an intrinsic correlation between the hot electron flow generated by internal photoemission and localized surface plasmon resonance.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2011/nalefd.2011.11.issue-10/nl2022459/production/images/medium/nl-2011-022459_0004.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl2022459'>ACS Electronic Supporting Info</A></P>