| 11. |
- Wan, Liyang, et al.
(författare)
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Molecular Degradation of Iron Phthalocyanine during the Oxygen Reduction Reaction in Acidic Media
- 2022
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Ingår i: ACS Catalysis. - : American Chemical Society (ACS). - 2155-5435. ; 12:18, s. 11097-11107
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Tidskriftsartikel (refereegranskat)abstract
- Molecular iron phthalocyanine (FePc) possesses an FeN4 active site structure similar to practical pyrolyzed Fe/N/C catalysts for the acidic oxygen reduction reaction (ORR), making it an ideal model system to derive the degradation mechanism of such catalysts. However, the degradation mechanism of FePc during the acidic ORR has been largely unclear to date. Herein, five most likely degradation factors affecting FePc-based ORR activity are individually investigated and compared. The attack by free radicals is found to be the main reason for the instability of FePc. Assisted by the combination of several spectroscopic methods, we successfully identify the degradation products and then propose a full structural evolution of molecular FePc degradation. Finally, high similarity in the decay mechanism between molecular FePc and practical Fe/N/C catalysts was present. This study provides a clear picture of the currently missing degradation mechanism of molecular FePc during acidic ORR, which will assist future investigations on the performance degradation of practical Fe/N/C catalysts.
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| 12. |
- Wang, Wei, 1995-, et al.
(författare)
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Mesoporous Ni-N-C as an efficient electrocatalyst for reduction of CO2 into CO in a flow cell
- 2022
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Ingår i: Applied Materials Today. - : Elsevier BV. - 2352-9407. ; 29
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Tidskriftsartikel (refereegranskat)abstract
- Recently, nitrogen-doped porous carbon materials containing non-precious metals (termed “M-N-C”) have formed a group of functional materials to replace precious metal-based catalysts for electrochemical CO2 reduction reaction. Here, a series of mesoporous Ni-N-C electrocatalysts (termed “mp-Ni-N-Cs”) were prepared via a gel-template method, and could effectively reduce CO2 into CO in a flow cell. The result in gas sorption tests exhibited a typical mesoporous structure, which would bring both sufficient exposed active sites and convenient mass transfer channels. Electrochemical tests showed excellent performance at an applied potential of -1.3 V (vs. RHE), e.g., a CO Faradaic efficiency (FECO) of 95.85 %, and a CO reduction current (jCO) of -21.29 mA cm−2. Significantly, its FECO exceeded 93 % in a wide range of potentials from -1.0 to -1.5 V, showing great tolerance to fluctuation in potential. The mp-Ni-N-C electrocatalysts have satisfactory features in terms of catalytic activity, facile preparation, and economic feasibility, and will offer a valuable reference for next exploration of cost-effective electrocatalysts for CO2 conversion.
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| 13. |
- Wang, Wei, et al.
(författare)
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Metal-Free SeBN Ternary-Doped Porous Carbon as Efficient Electrocatalysts for CO2 Reduction Reaction
- 2022
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Ingår i: ACS Applied Energy Materials. - : American Chemical Society (ACS). - 2574-0962. ; 5:9, s. 10518-10525
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Tidskriftsartikel (refereegranskat)abstract
- Cost-effective heteroatom-doped porous carbons are considered promising electrocatalysts for CO2 reduction reaction (CO2RR). Traditionally porous carbons with N doping or N/X codoping (X denotes the second type of heteroatom) have been widely studied, leaving ternary doping a much less studied yet exciting topic to be explored. Herein, a series of electrocatalysts based on metal-free Se, B, and N ternary-doped porous carbons (termed “SeBN-Cs”) were synthesized and tested as metal-free electrocatalysts in CO2RR. Our study indicates that the major product of CO2RR on the SeBN-C electrocatalysts was CO with a small fraction (<5%) of H2 as the byproduct. The optimal electrocatalyst sample SeBN-C-1100 prepared at 1100 °C exhibits a high CO selectivity with a Faradaic efficiency of CO reaching 95.2%. After 10 h of continuous electrolysis operation, the Faradaic efficiency and the current density are maintained high at 97.6 and 84.7% of the initial values, respectively, indicative of a long-term operational stability. This study provides an excellent reference to deepen our understanding of the properties and functions of multi-heteroatom-doped porous carbon electrocatalysts in CO2RR.
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| 14. |
- Wang, Yang, et al.
(författare)
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Lamellar carbon nitride membrane for enhanced ion sieving and water desalination
- 2022
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Membrane-based water treatment processes offer possibility to alleviate the water scarcity dilemma in energy-efficient and sustainable ways, this has been exemplified in filtration membranes assembled from two-dimensional (2D) materials for water desalination purposes. Most representatives however tend to swell or disintegrate in a hydrated state, making precise ionic or molecular sieving a tough challenge. Here we report that the chemically robust 2D carbon nitride can be activated using aluminum polycations as pillars to modulate the interlayer spacing of the conjugated framework, the noncovalent interaction concomitantly affords a well-interlinked lamellar structure, to be carefully distinguished from random stacking patterns in conventional carbon nitride membranes. The conformally packed membrane is characterized by adaptive subnanochannel and structure integrity to allow excellent swelling resistance, and breaks permeability-selectivity trade-off limit in forward osmosis due to progressively regulated transport passage, achieving high salt rejection (>99.5%) and water flux (6 L m−2 h−1), along with tunable permeation behavior that enables water gating in acidic and alkaline environments. These findings position carbon nitride a rising building block to functionally expand the 2D membrane library for applications in water desalination and purification scenarios.
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| 15. |
- Xie, Dongjiu, et al.
(författare)
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Poly(ionic liquid) Nanovesicle-Templated Carbon Nanocapsules Functionalized with Uniform Iron Nitride Nanoparticles as Catalytic Sulfur Host for Li–S Batteries
- 2022
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 16:7, s. 10554-10565
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Tidskriftsartikel (refereegranskat)abstract
- Poly(ionic liquid)s (PIL) are common precursors for heteroatom-doped carbon materials. Despite a relatively higher carbonization yield, the PIL-to-carbon conversion process faces challenges in preserving morphological and structural motifs on the nanoscale. Assisted by a thin polydopamine coating route and ion exchange, imidazolium-based PIL nanovesicles were successfully applied in morphology-maintaining carbonization to prepare carbon composite nanocapsules. Extending this strategy further to their composites, we demonstrate the synthesis of carbon composite nanocapsules functionalized with iron nitride nanoparticles of an ultrafine, uniform size of 3–5 nm (termed “FexN@C”). Due to its unique nanostructure, the sulfur-loaded FexN@C electrode was tested to efficiently mitigate the notorious shuttle effect of lithium polysulfides (LiPSs) in Li–S batteries. The cavity of the carbon nanocapsules was spotted to better the loading content of sulfur. The well-dispersed iron nitride nanoparticles effectively catalyze the conversion of LiPSs to Li2S, owing to their high electronic conductivity and strong binding power to LiPSs. Benefiting from this well-crafted composite nanostructure, the constructed FexN@C/S cathode demonstrated a fairly high discharge capacity of 1085 mAh g–1 at 0.5 C initially, and a remaining value of 930 mAh g–1 after 200 cycles. In addition, it exhibits an excellent rate capability with a high initial discharge capacity of 889.8 mAh g–1 at 2 C. This facile PIL-to-nanocarbon synthetic approach is applicable for the exquisite design of complex hybrid carbon nanostructures with potential use in electrochemical energy storage and conversion.
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| 16. |
- Xu, Hui, et al.
(författare)
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Impact of Pore Structure on Two-Electron Oxygen Reduction Reaction in Nitrogen-Doped Carbon Materials : Rotating Ring-Disk Electrode vs. Flow Cell
- 2022
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Ingår i: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 15:5
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Tidskriftsartikel (refereegranskat)abstract
- The impact of pore structure on the two-electron oxygen reduction reaction (ORR) in nitrogen-doped carbon materials is currently under debate, and previous studies are mainly limited to the rotating ring-disk electrode (RRDE) rather than the practical flow cell (FC) system. In this study, assisted by a group of reliable pore models, the impact of two pore structure parameters, that is, Brunauer–Emmett–Teller surface area (SBET) and micropore surface fraction (fmicro), on ORR activity and selectivity are investigated in both RRDE and FC. The ORR mass activity correlates positively to the SBET in the RRDE and FC because a higher SBET can host more active sites. The H2O2 selectivity is independent of fmicro in the RRDE but correlates negatively to fmicro in the FC. The inconsistency results from different states of the electrode in the RRDE and the FC. These insights will guide the design of carbon materials for H2O2 synthesis.
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| 17. |
- Yi, Ming, et al.
(författare)
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Poly(ionic liquid)-Armored MXene Membrane : Interlayer Engineering for Facilitated Water Transport
- 2022
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Ingår i: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 61:27
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Tidskriftsartikel (refereegranskat)abstract
- Two-dimensional (2D) MXene-based lamellar membranes bearing interlayers of tunable hydrophilicity are promising for high-performance water purification. The current challenge lies in how to engineer the pore wall's surface properties in the subnano-confinement environment while ensuring its high selectivity. Herein, poly(ionic liquid)s, equipped with readily exchangeable counter anions, succeeded as a hydrophilicity modifier in addressing this issue. Lamellar membranes bearing nanochannels of tailorable hydrophilicity are constructed via assembly of poly(ionic liquid)-armored MXene nanosheets. By shifting the interlayer galleries from being hydrophilic to more hydrophobic via simple anion exchange, the MXene membrane performs drastically better for both the permeance (by two-fold improvement) and rejection (≈99 %). This facile method opens up a new avenue for building 2D material-based membranes of enhancing molecular transport and sieving effect.
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| 18. |
- Zhang, Miao, et al.
(författare)
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Bridged Carbon Fabric Membrane with Boosted Performance in AC Line-Filtering Capacitors
- 2022
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Ingår i: Advanced Science. - : Wiley. - 2198-3844. ; 9:7
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Tidskriftsartikel (refereegranskat)abstract
- High-frequency responsive capacitors with lightweight, flexibility, and miniaturization are among the most vital circuit components because they can be readily incorporated into various portable devices to smooth out the ripples for circuits. Electrode materials no doubt are at the heart of such devices. Despite tremendous efforts and recent advances, the development of flexible and scalable high-frequency responsive capacitor electrodes with superior performance remains a great challenge. Herein, a straightforward and technologically relevant method is reported to manufacture a carbon fabric membrane “glued” by nitrogen-doped nanoporous carbons produced through a polyelectrolyte complexation-induced phase separation strategy. The as-obtained flexible carbon fabric bearing a unique hierarchical porous structure, and high conductivity as well as robust mechanical properties, serves as the free-standing electrode materials of electrochemical capacitors. It delivers an ultrahigh specific areal capacitance of 2632 µF cm−2 at 120 Hz with an excellent alternating current line filtering performance, fairly higher than the state-of-the-art commercial ones. Together, this system offers the potential electrode material to be scaled up for AC line-filtering capacitors at industrial levels.
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| 19. |
- Zhou, Shiqi, et al.
(författare)
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Vacancy-Rich MXene-Immobilized Ni Single Atoms as a High-Performance Electrocatalyst for the Hydrazine Oxidation Reaction
- 2022
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Ingår i: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 34:36
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Tidskriftsartikel (refereegranskat)abstract
- Single-atom catalysts (SACs), on account of their outstanding catalytic potential, are currently emerging as high-performance materials in the field of heterogeneous catalysis. Constructing a strong interaction between the single atom and its supporting matrix plays a pivotal role. Herein, Ti3C2Tx-MXene-supported Ni SACs are reported by using a self-reduction strategy via the assistance of rich Ti vacancies on the Ti3C2Tx MXene surface, which act as the trap and anchor sites for individual Ni atoms. The constructed Ni SACs supported by the Ti3C2Tx MXene (Ni SACs/Ti3C2Tx ) show an ultralow onset potential of −0.03 V (vs reversible hydrogen electrode (RHE)) and an exceptional operational stability toward the hydrazine oxidation reaction (HzOR). Density functional theory calculations suggest a strong coupling of the Ni single atoms and their surrounding C atoms, which optimizes the electronic density of states, increasing the adsorption energy and decreasing the reaction activation energy, thus boosting the electrochemical activity. The results presented here will encourage a wider pursuit of 2D-materials-supported SACs designed by a vacancy-trapping strategy.
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| 20. |
- Zhu, X., et al.
(författare)
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A Cation-Methylene-Phenyl Sequence Encodes Programmable Poly(Ionic Liquid) Coacervation and Robust Underwater Adhesion
- 2022
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Ingår i: Advanced Functional Materials. - : Wiley. - 1616-301X .- 1616-3028. ; 32:2
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Tidskriftsartikel (refereegranskat)abstract
- Appropriate deciphering and translation of sequence-dependent function in proteins is inspired by the cation–π interaction that is increasingly implicated in marine adhesives and membraneless organelles. A simplified cation-methylene-phenyl (C-M-P) sequence which enables triggerable poly(ionic liquid) coacervation is reported for the first time. Synthesis of the C-M-P structure motif requires only a one-step quaternization, which is facile compared to the linear sequence of distinct repeating units in model proteins and sequence-controlled polymers. The C-M-P code confers modular coacervation and advanced wet adhesion to task-specific copolymers. It allows for exceptional underwater adhesion to various submerged substrates including glass (≈1 MPa) and porcine skins (140 KPa), paving the way for prospective adhesive applications in physiological saline and underwater marine salvage. This work introduces a powerful code that, in addition to combining the advantageous adaptive adhesive and phase properties of proteins, reduces the complexity in sequence design for programmable coacervates.
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