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Fagiolari L, Bini M, Costantino F, Gatto G, Kropf AJ, Marmottini F, Nocchetti M, Wegener EC, Zaccaria F, Delferro M, Vivani R, Macchioni A. Iridium-Doped Nanosized Zn-Al Layered Double Hydroxides as Efficient Water Oxidation Catalysts. ACS APPLIED MATERIALS & INTERFACES 2020; 12:32736-32745. [PMID: 32583657 PMCID: PMC8008397 DOI: 10.1021/acsami.0c07925] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 06/25/2020] [Indexed: 05/29/2023]
Abstract
Layered double hydroxides (LDHs) are an ideal platform to host catalytic metal centers for water oxidation (WO) owing to the high accessibility of water to the interlayer region, which makes all centers potentially reachable and activated. Herein, we report the syntheses of three iridium-doped zinc-aluminum LDHs (Ir-LDHs) nanomaterials (1-3, with about 80 nm of planar size and a thickness of 8 nm as derived by field emission scanning electron microscopy and powder X-ray diffraction studies, respectively), carried out in the confined aqueous environment of reverse micelles, through a very simple and versatile procedure. These materials exhibit excellent catalytic performances in WO driven by NaIO4 at neutral pH and 25 °C, with an iridium content as low as 0.5 mol % (∼0.8 wt %), leading to quantitative oxygen yields (based on utilized NaIO4, turnover number up to ∼10,000). Nanomaterials 1-3 display the highest ever reported turnover frequency values (up to 402 min-1) for any heterogeneous and heterogenized catalyst, comparable only to those of the most efficient molecular iridium catalysts, tested under similar reaction conditions. The boost in activity can be traced to the increased surface area and pore volume (>5 times and 1 order of magnitude, respectively, higher than those of micrometric materials of size 0.3-1 μm) estimated for the nanosized particles, which guarantee higher noble metal accessibility. X-ray absorption spectroscopy (XAS) studies suggest that 1-3 nanomaterials, as-prepared and after catalysis, contain a mixture of isolated, single octahedral Ir(III) sites, with no evidence of Ir-Ir scattering from second-nearest neighbors, excluding the presence of IrO2 nanoparticles. The combination of the results obtained from XAS, elemental analysis, and ionic chromatography strongly suggests that iridium is embedded in the brucite-like structure of LDHs, having four hydroxyls and two chlorides as first neighbors. These results demonstrate that nanometric LDHs can be successfully exploited to engineer efficient WOCs, minimizing the amount of iridium used, consistent with the principle of the noble-metal atom economy.
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Affiliation(s)
- Lucia Fagiolari
- Department
of Chemistry, Biology and Biotechnology, University of Perugia and CIRCC, Via Elce di Sotto, 8, I-06123 Perugia, Italy
| | - Marzia Bini
- Department
of Pharmaceutical Sciences and CEMIN, University
of Perugia, Via Fabretti
48, I-06123 Perugia, Italy
| | - Ferdinando Costantino
- Department
of Chemistry, Biology and Biotechnology, University of Perugia and CIRCC, Via Elce di Sotto, 8, I-06123 Perugia, Italy
| | - Giordano Gatto
- Department
of Chemistry, Biology and Biotechnology, University of Perugia and CIRCC, Via Elce di Sotto, 8, I-06123 Perugia, Italy
| | - A. Jeremy Kropf
- Argonne
National Laboratory, Lemont, Illinois 60439, United States
| | - Fabio Marmottini
- Department
of Chemistry, Biology and Biotechnology, University of Perugia and CIRCC, Via Elce di Sotto, 8, I-06123 Perugia, Italy
| | - Morena Nocchetti
- Department
of Pharmaceutical Sciences and CEMIN, University
of Perugia, Via Fabretti
48, I-06123 Perugia, Italy
| | - Evan C. Wegener
- Argonne
National Laboratory, Lemont, Illinois 60439, United States
| | - Francesco Zaccaria
- Department
of Chemistry, Biology and Biotechnology, University of Perugia and CIRCC, Via Elce di Sotto, 8, I-06123 Perugia, Italy
| | | | - Riccardo Vivani
- Department
of Pharmaceutical Sciences and CEMIN, University
of Perugia, Via Fabretti
48, I-06123 Perugia, Italy
| | - Alceo Macchioni
- Department
of Chemistry, Biology and Biotechnology, University of Perugia and CIRCC, Via Elce di Sotto, 8, I-06123 Perugia, Italy
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Fagiolari L, Zaccaria F, Costantino F, Vivani R, Mavrokefalos CK, Patzke GR, Macchioni A. Ir- and Ru-doped layered double hydroxides as affordable heterogeneous catalysts for electrochemical water oxidation. Dalton Trans 2020; 49:2468-2476. [DOI: 10.1039/c9dt04306c] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Doping low-cost LDHs with noble metal atoms represents a promising approach to develop effective heterogeneous Water Oxidation Catalysts.
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Affiliation(s)
- Lucia Fagiolari
- Department of Chemistry
- Biology and Biotechnology
- Università di Perugia and CIRCC-Via Elce di Sotto 8
- I-06123 Perugia
- Italy
| | - Francesco Zaccaria
- Department of Chemistry
- Biology and Biotechnology
- Università di Perugia and CIRCC-Via Elce di Sotto 8
- I-06123 Perugia
- Italy
| | - Ferdinando Costantino
- Department of Chemistry
- Biology and Biotechnology
- Università di Perugia and CIRCC-Via Elce di Sotto 8
- I-06123 Perugia
- Italy
| | - Riccardo Vivani
- Department of Pharmaceutical Sciences
- Università di Perugia - Via del Liceo 1
- I-06123 Perugia
- Italy
| | | | - Greta R. Patzke
- Department of Chemistry
- University of Zurich - Winterthurerstrasse 190
- CH-8057 Zurich
- Switzerland
| | - Alceo Macchioni
- Department of Chemistry
- Biology and Biotechnology
- Università di Perugia and CIRCC-Via Elce di Sotto 8
- I-06123 Perugia
- Italy
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