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La JA, Lee H, Kim D, Ko H, Kang T. Enhanced Molecular Interaction of 3D Plasmonic Nanoporous Gold Alloys by Electronic Modulation for Sensitive Molecular Detection. NANO LETTERS 2024; 24:7025-7032. [PMID: 38832667 DOI: 10.1021/acs.nanolett.4c01505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2024]
Abstract
Three-dimensional gold and its alloyed nanoporous structures possess high surface areas and strong local electric fields, rendering them ideal substrates for plasmonic molecular detection. Despite enhancing plasmonic properties and altering molecular interactions, the effect of alloy composition on molecular detection capability has not yet been explored. Here, we report molecular interactions between nanoporous gold alloys and charged molecules by controlling the alloy composition. We demonstrate enhanced adsorption of negatively charged molecules onto the alloy surface due to positively charged gold atoms and a shifted d-band center through charge transfer between gold and other metals. Despite similar EM field intensities, nanoporous gold with silver (Au/Ag) achieves SERS enhancement factors (EF) up to 6 orders of magnitude higher than those of other alloys for negatively charged molecules. Finally, nanoporous Au/Ag detects amyloid-beta at concentrations as low as approximately 1 fM, with SERS EF up to 10 orders of magnitude higher than that of a monolayer of Au nanoparticles.
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Affiliation(s)
- Ju A La
- Institute of Integrated Biotechnology, Sogang University, Seoul 04107, Republic of Korea
| | - Hyunjoo Lee
- Department of Mechanical Engineering, Sogang University, Seoul 04107, Republic of Korea
| | - Dongchoul Kim
- Department of Mechanical Engineering, Sogang University, Seoul 04107, Republic of Korea
| | - Hyungduk Ko
- Nanophotonics Research Center, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 02792, Republic of Korea
- KHU-KIST Department of Converging Science and Technology, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Taewook Kang
- Institute of Integrated Biotechnology, Sogang University, Seoul 04107, Republic of Korea
- Department of Chemical and Biomoleuclar Engineering, Sogang University, Seoul 04107, Republic of Korea
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Artmann E, Schmider T, Jacob T, Engstfeld AK. Facet-Dependent Formation and Adhesion of Au Oxide and Nanoporous Au on Poly-Oriented Au Single Crystals. Chemphyschem 2023; 24:e202300428. [PMID: 37435757 DOI: 10.1002/cphc.202300428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Revised: 07/11/2023] [Accepted: 07/12/2023] [Indexed: 07/13/2023]
Abstract
Nanoporous Au (NPG) has different properties compared to bulk Au, making it an interesting material for numerous applications. To modify the structure of NPG films for specific applications, e. g., the porosity, thickness, and homogeneity of the films, a fundamental understanding of the structure formation is essential. Here, we focus on NPG prepared via electrochemical reduction from Au oxide formed during high voltage (HV) electrolysis on poly-oriented Au single crystal (Au POSC) electrodes. These POSCs consist of a metal bead, with faces with different crystallographic orientations and allow screening of the influence of crystallographic orientation on the structure formation for different facets in one experiment. The HV electrolysis is performed between 100 ms and 30 s at 300 V and 540 V. The amount of Au oxide formed is determined by electrochemical measurements and the structural properties are investigated by scanning electron and optical microscopy. We show that the formation of Au oxide is mostly independent of the crystallographic orientation, except for thick layers, while the macroscopic structure of the NPG films depends on experimental parameters such as the Au oxide precursor thickness and the crystallographic orientation of the substrate. Possible reasons for the frequently observed exfoliation of the NPG films are discussed.
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Affiliation(s)
- Evelyn Artmann
- Institute of Electrochemistry, Ulm University, D-89081, Ulm, Germany
| | - Tobias Schmider
- Institute of Electrochemistry, Ulm University, D-89081, Ulm, Germany
| | - Timo Jacob
- Institute of Electrochemistry, Ulm University, D-89081, Ulm, Germany
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Wittstock G, Bäumer M, Dononelli W, Klüner T, Lührs L, Mahr C, Moskaleva LV, Oezaslan M, Risse T, Rosenauer A, Staubitz A, Weissmüller J, Wittstock A. Nanoporous Gold: From Structure Evolution to Functional Properties in Catalysis and Electrochemistry. Chem Rev 2023; 123:6716-6792. [PMID: 37133401 DOI: 10.1021/acs.chemrev.2c00751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Nanoporous gold (NPG) is characterized by a bicontinuous network of nanometer-sized metallic struts and interconnected pores formed spontaneously by oxidative dissolution of the less noble element from gold alloys. The resulting material exhibits decent catalytic activity for low-temperature, aerobic total as well as partial oxidation reactions, the oxidative coupling of methanol to methyl formate being the prototypical example. This review not only provides a critical discussion of ways to tune the morphology and composition of this material and its implication for catalysis and electrocatalysis, but will also exemplarily review the current mechanistic understanding of the partial oxidation of methanol using information from quantum chemical studies, model studies on single-crystal surfaces, gas phase catalysis, aerobic liquid phase oxidation, and electrocatalysis. In this respect, a particular focus will be on mechanistic aspects not well understood, yet. Apart from the mechanistic aspects of catalysis, best practice examples with respect to material preparation and characterization will be discussed. These can improve the reproducibility of the materials property such as the catalytic activity and selectivity as well as the scope of reactions being identified as the main challenges for a broader application of NPG in target-oriented organic synthesis.
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Affiliation(s)
- Gunther Wittstock
- Carl von Ossietzky University of Oldenburg, School of Mathematics and Science, Institute of Chemistry, D-26111 Oldenburg, Germany
| | - Marcus Bäumer
- University of Bremen, Institute for Applied and Physical Chemistry, 28359 Bremen, Germany
- University of Bremen, MAPEX Center for Materials and Processes, 28359 Bremen, Germany
| | - Wilke Dononelli
- University of Bremen, MAPEX Center for Materials and Processes, 28359 Bremen, Germany
- University of Bremen, Bremen Center for Computational Materials Science, Hybrid Materials Interfaces Group, Am Fallturm 1, Bremen 28359, Germany
| | - Thorsten Klüner
- Carl von Ossietzky University of Oldenburg, School of Mathematics and Science, Institute of Chemistry, D-26111 Oldenburg, Germany
| | - Lukas Lührs
- Hamburg University of Technology, Institute of Materials Physics and Technology, 21703 Hamburg, Germany
| | - Christoph Mahr
- University of Bremen, MAPEX Center for Materials and Processes, 28359 Bremen, Germany
- University of Bremen, Institute of Solid State Physics, Otto Hahn Allee 1, 28359 Bremen, Germany
| | - Lyudmila V Moskaleva
- University of the Free State, Department of Chemistry, P.O. Box 339, Bloemfontein 9300, South Africa
| | - Mehtap Oezaslan
- Technical University of Braunschweig Institute of Technical Chemistry, Technical Electrocatalysis Laboratory, Franz-Liszt-Strasse 35a, 38106 Braunschweig, Germany
| | - Thomas Risse
- Freie Universität Berlin, Institute of Chemistry and Biochemistry, Arnimallee 22, 14195 Berlin, Germany
| | - Andreas Rosenauer
- University of Bremen, MAPEX Center for Materials and Processes, 28359 Bremen, Germany
- University of Bremen, Institute of Solid State Physics, Otto Hahn Allee 1, 28359 Bremen, Germany
| | - Anne Staubitz
- University of Bremen, MAPEX Center for Materials and Processes, 28359 Bremen, Germany
- University of Bremen, Institute for Organic and Analytical Chemistry, Leobener Strasse 7, D-28359 Bremen, Germany
| | - Jörg Weissmüller
- Hamburg University of Technology, Institute of Materials Physics and Technology, 21703 Hamburg, Germany
- Helmholtz-Zentrum Hereon, Institute of Materials Mechanics, 21502 Geesthacht, Germany
| | - Arne Wittstock
- University of Bremen, MAPEX Center for Materials and Processes, 28359 Bremen, Germany
- University of Bremen, Institute for Organic and Analytical Chemistry, Leobener Strasse 7, D-28359 Bremen, Germany
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