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Two Manganese Metalloporphyrin Frameworks Constructed from a Custom-Designed Porphyrin Ligand Exhibiting Selective Uptake of CO 2 over CH 4 and Catalytic Activity for CO 2 Fixation
- Award ID(s):
- 1834750
- PAR ID:
- 10316204
- Date Published:
- Journal Name:
- Crystal Growth & Design
- Volume:
- 21
- Issue:
- 5
- ISSN:
- 1528-7483
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Ion beam-induced deposition (IBID) using Pt(CO)2Cl2and Pt(CO)2Br2as precursors has been studied with ultrahigh-vacuum (UHV) surface science techniques to provide insights into the elementary reaction steps involved in deposition, complemented by analysis of deposits formed under steady-state conditions. X-ray photoelectron spectroscopy (XPS) and mass spectrometry data from monolayer thick films of Pt(CO)2Cl2and Pt(CO)2Br2exposed to 3 keV Ar+, He+, and H2+ions indicate that deposition is initiated by the desorption of both CO ligands, a process ascribed to momentum transfer from the incident ion to adsorbed precursor molecules. This precursor decomposition step is accompanied by a decrease in the oxidation state of the Pt(II) atoms and, in IBID, represents the elementary reaction step that converts the molecular precursor into an involatile PtX2species. Upon further ion irradiation these PtCl2or PtBr2species experience ion-induced sputtering. The difference between halogen and Pt sputter rates leads to a critical ion dose at which only Pt remains in the film. A comparison of the different ion/precursor combinations studied revealed that this sequence of elementary reaction steps is invariant, although the rates of CO desorption and subsequent physical sputtering were greatest for the heaviest (Ar+) ions. The ability of IBID to produce pure Pt films was confirmed by AES and XPS analysis of thin film deposits created by Ar+/Pt(CO)2Cl2, demonstrating the ability of data acquired from fundamental UHV surface science studies to provide insights that can be used to better understand the interactions between ions and precursors during IBID from inorganic precursors.more » « less
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null (Ed.)Two platinum precursors, Pt(CO) 2 Cl 2 and Pt(CO) 2 Br 2 , were designed for focused electron beam-induced deposition (FEBID) with the aim of producing platinum deposits of higher purity than those deposited from commercially available precursors. In this work, we present the first deposition experiments in a scanning electron microscope (SEM), wherein series of pillars were successfully grown from both precursors. The growth of the pillars was studied as a function of the electron dose and compared to deposits grown from the commercially available precursor MeCpPtMe 3 . The composition of the deposits was determined using energy-dispersive X-ray spectroscopy (EDX) and compared to the composition of deposits from MeCpPtMe 3 , as well as deposits made in an ultrahigh-vacuum (UHV) environment. A slight increase in metal content and a higher growth rate are achieved in the SEM for deposits from Pt(CO) 2 Cl 2 compared to MeCpPtMe 3 . However, deposits made from Pt(CO) 2 Br 2 show slightly less metal content and a lower growth rate compared to MeCpPtMe 3 . With both Pt(CO) 2 Cl 2 and Pt(CO) 2 Br 2 , a marked difference in composition was found between deposits made in the SEM and deposits made in UHV. In addition to Pt, the UHV deposits contained halogen species and little or no carbon, while the SEM deposits contained only small amounts of halogen species but high carbon content. Results from this study highlight the effect that deposition conditions can have on the composition of deposits created by FEBID.more » « less
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Electrochemical CO2 capture approaches, where electrochemical reactions control the sorbent’s CO2 affinity to drive subsequent CO2 absorption/desorption, have gained substantial attention due to their low energy demands compared to temperature-swing approaches. Typically, the process uses separate electrochemical and mass-transfer steps, producing a 4-stage (cathodic/anodic, absorption/desorption) process, but recent work proposed that these energy demands can be further reduced by combining the electrochemical and CO2 mass-transfer reactor units. Here, we used computational models to examine the practical benefit of combining electrochemical sorbent reactivation with CO2 absorption due to this combination’s implicit assumptions about the process rate and therefore, the reactor size and cost. Comparing the minimum energy demand and process time of this combined reactor to those of the separated configuration, we found that the combined absorber can reduce the energy demand by up to 67% but doing so can also increase the process time by several orders of magnitude. In contrast, optimizing the solution chemistry could benefit both the energy demand and process time simultaneously.more » « less
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1021/acs.cgd.0c01694
