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Zhou J, Leung TK, Peng Z, Li X, Chen K, Yuan J, Leung MKH. Balancing Volmer Step by Superhydrophilic Dual-Active Domains for Enhanced Hydrogen Evolution. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2300441. [PMID: 37118851 DOI: 10.1002/smll.202300441] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Revised: 03/18/2023] [Indexed: 06/19/2023]
Abstract
The reaction kinetics of hydrogen evolution reaction (HER) is largely determined by balancing the Volmer step in alkaline media. Bifunctionality as a proposed strategy can divide the work of water dissociation and intermediates (OH* and H*) adsorption/desorption. However, sluggish OH* desorption plagues water re-adsorption, which leads to poisoning effects of active sites. Some active sites may even directly act as spectators and do not participate in the reaction. Furthermore, the activity comparison under approximate nanostructure between bifunctional effect and single-exposed active sites is not fully understood. Here, a facile three-step strategy is adopted to successfully grow molybdenum disulfide (MoS2 ) on cobalt-containing nitrogen-doped carbon nanotubes (Co-NCNTs), forming obvious dual active domains. The active sites on domains of Co-NCNTs and MoS2 and the tuned electronic structure at the heterointerface trigger the bifunctional effect to balance the Volmer step and improve the catalytic activity. The HER driven by the bifunctional effect can significantly optimize the Gibbs free energy of water dissociation and hydrogen adsorption, resulting in fast reaction kinetics and superior catalytic performance. As a result, the Co-NCNTs/MoS2 catalyst outperforms other HER electrocatalysts with low overpotential (58 and 84 mV at 10 mA cm-2 in alkaline and neutral conditions, respectively), exceptional stability, and negligible degradation.
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Affiliation(s)
- Jinsong Zhou
- Ability R&D Energy Research Centre, School of Energy and Environment, City University of Hong Kong, Kowloon, Hong Kong, China
| | - Tsz Kei Leung
- Ability R&D Energy Research Centre, School of Energy and Environment, City University of Hong Kong, Kowloon, Hong Kong, China
| | - Zehua Peng
- Ability R&D Energy Research Centre, School of Energy and Environment, City University of Hong Kong, Kowloon, Hong Kong, China
| | - Xin Li
- Ability R&D Energy Research Centre, School of Energy and Environment, City University of Hong Kong, Kowloon, Hong Kong, China
| | - Keda Chen
- Ability R&D Energy Research Centre, School of Energy and Environment, City University of Hong Kong, Kowloon, Hong Kong, China
| | - Jiaxin Yuan
- Ability R&D Energy Research Centre, School of Energy and Environment, City University of Hong Kong, Kowloon, Hong Kong, China
| | - Michael K H Leung
- State Key Laboratory of Marine Pollution, City University of Hong Kong, Kowloon, Hong Kong, China
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[Hexaamminecobalt(III)] Dichloride Permanganate—Structural Features and Heat-Induced Transformations into (CoII,MnII)(CoIII,MnIII)2O4 Spinels. INORGANICS 2022. [DOI: 10.3390/inorganics10120252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
We synthesized and characterized (IR, Raman, UV, SXRD) hexaamminecobalt(III) dichloride permanganate, [Co(NH3)6]Cl2(MnO4) (compound 1) as the precursor of Co–Mn–spinel composites with atomic ratios of Co:Mn = 1:1 and 1:3. The 3D−hydrogen bond network includes N–HO–Mn and N–HCl interactions responsible for solid-phase redox reactions between the permanganate anions and ammonia ligands. The temperature-limited thermal decomposition of compound 1 under the temperature of boiling toluene (110 ∘C) resulted in the formation of (NH4)4Co2Mn6O12. which contains a todorokite-like manganese oxide network (MnII4MnIII2O1210−). The heat treatment products of compounds 1 and [Co(NH3)5Cl](MnO4)2 (2) synthesized previously at 500 ∘C were a cubic and a tetragonal spinel with Co1.5Mn1.5O4 and CoMn2O4 composition, respectively. The heating of the decomposition product of compounds 1 and 2 that formed under refluxing toluene (a mixture with an atomic ratio of Co:Mn = 1:1 and 1:2) and after aqueous leaching ((NH4)4Co2Mn6O12, 1:3 Co:Mn atomic ratio in both cases) at 500 ∘C resulted in tetragonal Co0.75Mn2.25O4 spinels. The Co1.5Mn1.5O4 prepared from compound 1 at 500 ∘C during the solid-phase decomposition catalyzes the degradation of Congo red with UV light. The decomposition rate of the dye was found to be nine times faster than in the presence of the tetragonal CoMn2O4 spinel prepared in the solid-phase decomposition of compound 2. The todorokite-like intermediate prepared from compound 1 under N2 at 115 ∘C resulted in a 54 times faster degradation of Congo red, which is a great deal faster than the same todorokite-like phase that formed from compound 2 under N2.
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Multi-Centered Solid-Phase Quasi-Intramolecular Redox Reactions of [(Chlorido)Pentaamminecobalt(III)] Permanganate—An Easy Route to Prepare Phase Pure CoMn2O4 Spinel. INORGANICS 2022. [DOI: 10.3390/inorganics10020018] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
We synthesized and structurally characterized the previously unknown [Co(NH3)5Cl](MnO4)2 complex as the precursor of CoMn2O4. The complex was also deuterated, and its FT-IR, far-IR, low-temperature Raman and UV-VIS spectra were measured as well. The structure of the complex was solved by single-crystal X-ray diffraction and the 3D-hydrogen bonds were evaluated. The N-H…O-Mn hydrogen bonds act as redox centers to initiate a solid-phase quasi-intramolecular redox reaction even at 120 °C involving the Co(III) centers. The product is an amorphous material, which transforms into [Co(NH3)5Cl]Cl2, NH4NO3, and a todorokite-like solid Co-Mn oxide on treatment with water. The insoluble residue may contain {Mn4IIIMnIV2O12}n4n-, {Mn5IIIMnIVO12}n5n- or {MnIII6O12}n6n- frameworks, which can embed 2 × n (CoII and/or CoIII) cations in their tunnels, respectively, and 4 × n ammonia ligands are coordinated to the cobalt cations. The decomposition intermediates decompose on further heating via a series of redox reactions, forming a solid CoIIMIII2O4 spinel with an average size of 16.8 nm, and gaseous N2, N2O and Cl2. The CoMn2O4 prepared in this reaction has photocatalytic activity in Congo red degradation with UV light. Its activity strongly depends on the synthesis conditions, e.g., Congo red was degraded 9 and 13 times faster in the presence of CoMn2O4 prepared at 550 °C (in air) or 420 °C (under N2), respectively.
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Ozvat TM, Rappé AK, Zadrozny JM. Isotopomeric Elucidation of the Mechanism of Temperature Sensitivity in 59Co NMR Molecular Thermometers. Inorg Chem 2022; 61:778-785. [PMID: 34962806 PMCID: PMC9531048 DOI: 10.1021/acs.inorgchem.1c03326] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Understanding the mechanisms governing temperature-dependent magnetic resonance properties is essential for enabling thermometry via magnetic resonance imaging. Herein we harness a new molecular design strategy for thermometry─that of effective mass engineering via deuteration in the first coordination shell─to reveal the mechanistic origin of 59Co chemical shift thermometry. Exposure of [Co(en)3]3+ (1; en = ethylenediamine) and [Co(diNOsar)]3+ (2; diNOsar = dinitrosarcophagine) to mixtures of H2O and D2O produces distributions of [Co(en)3]3+-dn (n = 0-12) and [Co(diNOsar)]3+-dn (n = 0-6) isotopomers all resolvable by 59Co NMR. Variable-temperature 59Co NMR analyses reveal a temperature dependence of the 59Co chemical shift, Δδ/ΔT, on deuteration of the N-donor atoms. For 1, deuteration amplifies Δδ/ΔT by 0.07 ppm/°C. Increasing degrees of deuteration yield an opposing influence on 2, diminishing Δδ/ΔT by -0.07 ppm/°C. Solution-phase Raman spectroscopy in the low-frequency 200-600 cm-1 regime reveals a red shift of Raman-active Co-N6 vibrational modes by deuteration. Analysis of the normal vibrational modes shows that Raman modes produce the largest variation in 59Co δ. Finally, partition function analysis of the Raman-active modes shows that increased populations of Raman modes predict greater Δδ/ΔT, representing new experimental insight into the thermometry mechanism.
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Affiliation(s)
- Tyler M. Ozvat
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Anthony K. Rappé
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Joseph M. Zadrozny
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
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Ozvat TM, Peña ME, Zadrozny JM. Influence of ligand encapsulation on cobalt-59 chemical-shift thermometry. Chem Sci 2019; 10:6727-6734. [PMID: 31367328 PMCID: PMC6625495 DOI: 10.1039/c9sc01689a] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2019] [Accepted: 06/04/2019] [Indexed: 11/21/2022] Open
Abstract
This manuscript details the first investigation of ligand encapsulation on thermometry by cobalt-59 nuclear spins.
Thermometry via magnetic resonance imaging (MRI) would provide a powerful noninvasive window into physiological temperature management. Cobalt-59 nuclear spins demonstrate exceptional temperature dependence of their NMR chemical shifts, yet the insight to control this dependence via molecular design is lacking. We present the first systematic evidence that encapsulation of this spin system amplifies the temperature sensitivity. We tested the temperature dependence of the 59Co chemical shift (Δδ/ΔT) in a series of five low-spin cobalt(iii) complexes as a function of increasing encapsulation within the 1st coordination sphere. This study spans from [Co(NH3)6]Cl3, with no interligand connectivity, to a fully encapsulated dinitrosarcophagine (diNOsar) complex, [Co(diNOsar)]Cl3. We discovered Δδ/ΔT values that span from 1.44(2) ppm °C–1 in [Co(NH3)6]Cl3 to 2.04(2) ppm °C–1 in [Co(diNOsar)]Cl3, the latter among the highest for a molecular complex. The data herein suggest that designing 59Co NMR thermometers toward high chemical stability can be coincident with high Δδ/ΔT. To better understand this phenomenon, variable-temperature UV-Vis, 59Co NMR relaxation, Raman spectroscopic, and variable-solvent investigations were performed. Data from these measurements highlight an unexpected impact of encapsulation – an increasingly dynamic and flexible inner coordination sphere. These results comprise the first systematic studies to reveal insight into the molecular factors that govern Δδ/ΔT and provide the first evidence of 59Co nuclear-spin control via vibrational means.
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Affiliation(s)
- Tyler M Ozvat
- Department of Chemistry , Colorado State University , Fort Collins , Colorado 80523 , USA .
| | - Manuel E Peña
- Department of Chemistry , Colorado State University , Fort Collins , Colorado 80523 , USA .
| | - Joseph M Zadrozny
- Department of Chemistry , Colorado State University , Fort Collins , Colorado 80523 , USA .
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Vivier V, Aguey F, Fournier J, Lambert JF, Bedioui F, Che M. Spectroscopic and Electrochemical Study of the Adsorption of [Co(en)2Cl2]Cl on γ-Alumina: Influence of the Alumina Ligand on Co(III)/(II) Redox Potential. J Phys Chem B 2005; 110:900-6. [PMID: 16471621 DOI: 10.1021/jp058224x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
UV-visible and Raman spectroscopies as well as electrochemical techniques have been used to characterize cis- and trans-[Co(III)(en)2Cl2]Cl (en=ethylenediamine) complexes and the gamma-alumina-supported cis-Co((III)) complex. It is shown that the electrochemical reduction of these complexes occurs according to a multistage mechanism involving two electrochemical steps, with the formation of a dimer that was characterized by UV-visible spectroscopy (intervalence band at 670 nm). The apparent standard redox potential for each step has been determined, and experimental results reveal that cis and trans complexes present similar electrochemical characteristics. It is also shown that the deposition of trans-[Co(III)(en)2Cl2]+ on gamma-alumina leads to an inner-sphere complex (ISC) in a cis configuration in which Cl- ligands are substituted by OH or O- surface groups of alumina. These changes in the coordination sphere of the complex induce a substantial decrease of its apparent redox potential since it is -0.63 V/SCE (saturated calomel electrode) for the gamma-alumina-supported cis-Co(III) complex, whereas values of -0.17 and -0.35 V/SCE were determined in dimethyl sulfoxide (DMSO) for the trans and cis precursor complexes, respectively.
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Affiliation(s)
- Vincent Vivier
- Laboratoire de Réactivité de Surface, UMR 7609-CNRS, Université Pierre & Marie Curie, 4 place Jussieu, Casier 178, 75252 Paris Cedex 05, France.
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Phase transition and molecular motions in [Cr(NH3)6](BF4)3 studied by differential scanning calorimetry, infrared spectroscopy and X-ray diffraction. J Mol Struct 2004. [DOI: 10.1016/j.molstruc.2004.02.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Mikuli E, Migdał-Mikuli A, Górska N, Wróbel S, Ściesiński J, Ściesińska E. Phase transition and molecular motions in [Co(NH3)6](ClO4)3 studied by differential scanning calorimetry and infrared spectroscopy. J Mol Struct 2003. [DOI: 10.1016/s0022-2860(03)00114-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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John A, Philip D, Morgan KR, Devanarayanan S. IR and raman spectra of two layered aluminium phosphates Co(en)3Al3P4O16.3H2O and. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2000; 56:2715-2723. [PMID: 11145338 DOI: 10.1016/s1386-1425(00)00314-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The FT IR and FT Raman spectra of Co(en)3Al3P4O16.3H2O (compound I) and [NH4]3[Co(NH3)6]3[Al2 (PO4)4]2.2H2O (compound II) are recorded and analysed based on the vibrations of Co(en)(3)3+, Co(NH3)(6)3+, NH4, Al-O-P, PO3, PO2 and H2O. The observed splitting of bands indicate that the site symmetry and correlation field effects are appreciable in both the compounds. In compound I, the overtone of CH2 deformation Fermi resonates with its symmetric stretching vibration. The NH4 ion in compound II is not free to rotate in the crystalline lattice. Hydrogen bonding of different groups is also discussed.
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Affiliation(s)
- A John
- St John's College, Anchal, Kollam, India
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Chen Y, Hyldtoft J, Jacobsen CJ, Christensen DH, Nielsen OF. Impregnation of ammine aqua cobalt(III) complexes on η-Al2O3 investigated by NIR FT-Raman spectroscopy. ACTA ACUST UNITED AC 1994. [DOI: 10.1016/0584-8539(94)80200-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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