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Moshrefi R, Ryan K, Connors EP, Walsh JC, Merschrod E, Bodwell GJ, Stockmann TJ. Electrosynthesis of Au nanocluster embedded conductive polymer films at soft interfaces using dithiafulvenyl-functionalized pyrene. NANOSCALE 2023; 15:5834-5842. [PMID: 36861258 DOI: 10.1039/d2nr06519c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Nanoparticle (NP) embedded conductive polymer films are desirable platforms for electrocatalysis as well as biomedical and analytical applications. Increased catalytic and analytical performance is accompanied by concomitant decreases in NP size. Herein, highly reproducible electrogeneration of low dispersity Au nanocluster embedded ultra-thin (∼2 nm) conductive polymer films at a micro liquid|liquid interface is demonstrated. Confinement at a micropipette tip facilitates a heterogeneous electron transfer process across the interface between two immiscible electrolyte solutions (ITIES), between KAuCl4(aq) and a dithiafulvenyl-substituted pyrene monomer, 4,5-didecoxy-1,8-bis(dithiafulven-6-yl)pyrene (bis(DTF)pyrene), in oil, i.e., a w|o interface. At a large ITIES the reaction is spontaneous, rapid, and proceeds via transfer of AuCl4- to the oil phase, followed by homogeneous electron transfer generating uncontrolled polymer growth with larger (∼50 nm) Au nanoparticles (NPs). Thus, miniaturization facilitates external, potential control and limits the reaction pathway. Atomic (AFM) and Kelvin probe force microscopies (KPFM) imaged the topography and work function distribution of the as-prepared films. The latter was linked to nanocluster distribution.
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Affiliation(s)
- Reza Moshrefi
- Memorial University of Newfoundland, Core Science Facility, 45 Arctic Ave, St. John's, NL, Canada, A1C 5S7.
| | - Katelyn Ryan
- Memorial University of Newfoundland, Core Science Facility, 45 Arctic Ave, St. John's, NL, Canada, A1C 5S7.
| | - Evan P Connors
- Memorial University of Newfoundland, Core Science Facility, 45 Arctic Ave, St. John's, NL, Canada, A1C 5S7.
| | - Joshua C Walsh
- Memorial University of Newfoundland, Core Science Facility, 45 Arctic Ave, St. John's, NL, Canada, A1C 5S7.
| | - Erika Merschrod
- Memorial University of Newfoundland, Core Science Facility, 45 Arctic Ave, St. John's, NL, Canada, A1C 5S7.
| | - Graham J Bodwell
- Memorial University of Newfoundland, Core Science Facility, 45 Arctic Ave, St. John's, NL, Canada, A1C 5S7.
| | - Talia Jane Stockmann
- Memorial University of Newfoundland, Core Science Facility, 45 Arctic Ave, St. John's, NL, Canada, A1C 5S7.
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Moshrefi R, Stockmann TJ. Electrodeless Synthesis of Low Dispersity Au Nanoparticles and Nanoclusters at an Immiscible Micro Water/Ionic Liquid Interface. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:2748. [PMID: 36014613 PMCID: PMC9416156 DOI: 10.3390/nano12162748] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 08/08/2022] [Accepted: 08/09/2022] [Indexed: 06/15/2023]
Abstract
Owing to their biocompatibility, optical, and catalytic properties, Au nanoparticles (NPs) have been the subject of much research. Since smaller NPs have enhanced catalytic properties and NP morphology greatly impacts their effectiveness, controlled and reproducible methods of generating Au NPs are still being sought. Herein, Au NPs were electrochemically generated at a water|ionic liquid (w|IL) immiscible micro-interface, 25 µm in diameter, using a redox active IL and compared to results at a water|oil (w|o) one. The liquid|liquid interface is advantageous as it is pristine and highly reproducible, as well as an excellent means of species and charge separation. In this system, KAuCl4 dissolved in the aqueous phase reacts under external potential control at the water|P8888TB (tetraoctylphosphonium tetrakis(pentafluorophenyl)borate) with trioctyl(ferrocenylhexanoyl)phosphonium tetrakis(pentafluorophenyl)borate (FcIL), an electron donor and redox active IL. FcIL was prepared with a common anion to P8888TB, which greatly enhances its solubility in the bulk IL. Simple ion transfer of AuCl4− and AuCl(4−γ)(OH)γ− at the w|P8888TB micro-interface were characterized voltammetrically as well as their heterogeneous electron transfer reaction with FcIL. This interfacial reaction generates Au NPs whose size can be thermodynamically controlled by modifying the pH of the aqueous phase. Critically, at low pH, nanoclusters, <1.7 nm in diameter, were generated owing to inhibited thermodynamics in combination with the supramolecular fluidic nature of the IL microenvironment that was observed surrounding the as-prepared NPs.
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