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Kwon, Han Chang,Kim, Minho,Grote, Jan-Philipp,Cho, Sung June,Chung, Min Wook,Kim, Haesol,Won, Da Hye,Zeradjanin, Aleksandar R.,Mayrhofer, Karl J. J.,Choi, Minkee,Kim, Hyungjun,Choi, Chang Hyuck American Chemical Society 2018 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.140 No.47
<P>Carbon monoxide is widely known to poison Pt during heterogeneous catalysis owing to its strong donor-acceptor binding ability. Herein, we report a counterintuitive phenomenon of this general paradigm when the size of Pt decreases to an atomic level, namely, the CO-promoting Pt electrocatalysis toward hydrogen evolution reactions (HER). Compared to pristine atomic Pt catalyst, reduction current on a CO-modified catalyst increases significantly. Operando mass spectroscopy and electrochemical analyses demonstrate that the increased current arises due to enhanced H<SUB>2</SUB> evolution, not additional CO reduction. Through structural identification of catalytic sites and computational analysis, we conclude that CO-ligation on the atomic Pt facilitates H<SUB>ads</SUB> formation via water dissociation. This counterintuitive effect exemplifies the fully distinct characteristics of atomic Pt catalysts from those of bulk Pt, and offers new insights for tuning the activity of similar classes of catalysts.</P> [FIG OMISSION]</BR>
High-Performance Flexible ZnO Nanorod UV/Gas Dual Sensors Using Ag Nanoparticle Templates
Kwon, Do-Kyun,Porte, Yoann,Ko, Kyung Yong,Kim, Hyungjun,Myoung, Jae-Min American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.37
<P>Flexible zinc oxide (ZnO) nanorod (NR) ultraviolet (UV)/gas dual sensors using silver (Ag) nanoparticle (NP) templates were successfully fabricated on a polyimide substrate with nickel electrodes. Arrays of Ag NPs were used as a template for the growth of ZnO NRs, which could enhance the flexibility and the sensing properties of the devices through the localized surface plasmon resonance (LSPR) effect. The Ag NPs were fabricated by the rapid thermal annealing process of Ag thin films, and ZnO NRs were grown on Ag NPs to maximize the surface area and form networks with rod-to-rod contacts. Because of the LSPR effect by Ag NPs, the UV photoresponse of the ZnO NRs was amplified and the depletion region of ZnO NRs was formed quickly because of the Schottky contact with the Ag NPs. As a consequence, ZnO NR UV/gas dual sensors grown on the Ag NP template with a diameter of 28 nm exhibited the outstanding UV-sensing characteristics with a UV on-off ratio of 3628 and a rising time (<I>t</I><SUB>r</SUB>) and a decay time (<I>t</I><SUB>d</SUB>) of 3.52 and 0.33 s upon UV exposure, along with excellent NO<SUB>2</SUB>-sensing characteristics with a stable gas on-off ratio of 288.5 and a <I>t</I><SUB>r</SUB> and <I>t</I><SUB>d</SUB> of 38 and 62 s upon NO<SUB>2</SUB> exposure. Furthermore, the sensors grown on the Ag NP template exhibited good mechanical flexibility and stable sensing properties without significant degradation even after the bending test up to 10 000 cycles at the bending radius of 5 mm.</P> [FIG OMISSION]</BR>