| 1. |
- Wang, Tongzhou, et al.
(författare)
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Atomically Dispersed Semi-Metallic Selenium on Porous Carbon Membrane as an Electrode for Hydrazine Fuel Cells
- 2019
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Ingår i: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 58:38, s. 13466-13471
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Tidskriftsartikel (refereegranskat)abstract
- Electrochemically functional porous membranes of low cost are appealing in various electrochemical devices used in modern environmental and energy technologies. Herein we describe a scalable strategy to construct electrochemically active, hierarchically porous carbon membranes containing atomically dispersed semi-metallic Se, denoted SeNCM. The isolated Se atoms were stabilized by carbon atoms in the form of a hexatomic ring structure, in which the Se atoms were located at the edges of graphitic domains in SeNCM. This configuration is different from that of previously reported transition/noble metal single atom catalysts. The positively charged Se, enlarged graphitic layers, robust electrochemical nature of SeNCM endow them with excellent catalytic activity that is superior to state-of-the-art commercial Pt/C catalyst. It also has long-term operational stability for hydrazine oxidation reaction in practical hydrazine fuel cell.
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| 2. |
- Chen, Zhi, et al.
(författare)
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Large-Area Crystalline Zeolitic Imidazolate Framework Thin Films
- 2021
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Ingår i: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 60:25, s. 14124-14130
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Tidskriftsartikel (refereegranskat)abstract
- We report that continuous MOF films with highly controlled thickness (from 44 to 5100 nm) can be deposited over length scales greater than 80 centimeters by a facile, fast, and cost-effective spray-coating method. Such success relies on our discovery of unprecedented perfectly dispersed colloidal solutions consisting of amorphous MOF nanoparticles, which we adopted as precursors that readily converted to the crystalline films upon low-temperature in situ heating. The colloidal solutions allow for the fabrication of compact and uniform MOF films on a great deal of substrates such as fluorine-doped tin oxide, glass, SiO2, Al2O3, Si, Cu, and even flexible polycarbonate, widening their technological applications where substrates are essential. Despite the present work focuses on the fabrication of uniform cobalt-(2-methylimidazole)2 and zinc-(2-methylimidazole)2 films, our findings mark a great possibility in producing other high-quality MOF thin films on a large scale.
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| 3. |
- Pang, Kanglei, 1993-, et al.
(författare)
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Redirecting configuration of atomically dispersed selenium catalytic sites for efficient hydrazine oxidation
- 2024
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Ingår i: Matter. - 2590-2393 .- 2590-2385. ; 7:2, s. 655-667
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the reconstruction of surface sites is crucial for gaining insights into the true active sites and catalytic mechanisms. While extensive research has been conducted on reconstruction behaviors of atomically dispersed metallic catalytic sites, limited attention has been paid to non-metallic ones despite their potential catalytic activity comparable or even superior to their noble-metal counterpart. Herein, we report a carbonaceous, atomically dispersed non-metallic selenium catalyst that displayed exceptional catalytic activity in the hydrazine oxidation reaction (HzOR) in alkaline media, outperforming the noble-metal Pt catalysts. In situ X-ray absorption spectroscopy (XAS) and Fourier transform infrared spectroscopy revealed that the pristine SeC4 site pre-adsorbs an ∗OH ligand, followed by HzOR occurring on the other side of the OH–SeC4. Theoretical calculations proposed that the pre-adsorbed ∗OH group pulls electrons from the Se site, resulting in a more positively charged Se and a higher polarity of Se–C bonds, thereby enhancing surface reactivity toward HzO/R.
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| 4. |
- Wang, Binmin, et al.
(författare)
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Multifunctional Underwater Adhesive Film Enabled by a Single-Component Poly(ionic liquid)
- 2023
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 17:6, s. 5871-5879
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Tidskriftsartikel (refereegranskat)abstract
- Tremendous efforts have been devoted to exploiting synthetic wet adhesives for real-life applications. However, developing low-cost, robust, and multifunctional wet adhesive materials remains a considerable challenge. Herein, a wet adhesive composed of a single-component poly(ionic liquid) (PIL) that enables fast and robust underwater adhesion is reported. The PIL adhesive film possesses excellent stretchability and flexibility, enabling its anchoring on target substrates regardless of deformation and water scouring. Surface force measurements show the PIL can achieve a maximum adhesion of 56.7 mN·m–1 on diverse substrates (both hydrophilic and hydrophobic substrates) in aqueous media, within ∼30 s after being applied. The adhesion mechanisms of the PIL were revealed via the force measurements, and its robust wet adhesive capacity was ascribed to the synergy of different non-covalent interactions, such as of hydrogen bonding, cation−π, electrostatic, and van der Waals interactions. Surprisingly, this PIL adhesive film exhibited impressive underwater sound absorption capacity. The absorption coefficient of a 0.7 mm-thick PIL film to 4–30 kHz sound waves could be as high as 0.80–0.92. This work reports a multifunctional PIL wet adhesive that has promising applications in many areas and provides deep insights into interfacial interaction mechanisms underlying the wet adhesion capability of PILs.
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| 5. |
- Wang, Hong, et al.
(författare)
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Ambient Electrosynthesis of Ammonia : Electrode Porosity and Composition Engineering
- 2018
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Ingår i: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 57:38, s. 12360-12364
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Tidskriftsartikel (refereegranskat)abstract
- Ammonia, a key precursor for fertilizer production, convenient hydrogen carrier, and emerging clean fuel, plays a pivotal role in sustaining life on Earth. Currently, the main route for NH3 synthesis is by the heterogeneous catalytic Haber-Bosch process (N-2+ 3H(2) -> 2NH(3)), which proceeds under extreme conditions of temperature and pressure with a very large carbon footprint. Herein we report that a pristine nitrogen-doped nanoporous graphitic carbon membrane (NCM) can electrochemically convert N-2 into NH3 in an acidic aqueous solution under ambient conditions. The Faradaic efficiency and rate of production of NH3 on the NCM electrode reach 5.2% and 0.08 gm(-2) h(-1), respectively. Functionalization of the NCM with Au nanoparticles dramatically enhances these performance metrics to 22% and 0.36 gm(-2) h(-1), respectively. As this system offers the potential to be scaled to industrial levels it is highly likely that it might displace the century-old Haber-Bosch process.
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| 6. |
- Wang, Yu-Cheng, et al.
(författare)
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Porous Carbon Membrane-Supported Atomically Dispersed Pyrrole-Type Fe-N-4 as Active Sites for Electrochemical Hydrazine Oxidation Reaction
- 2020
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Ingår i: Small. - : Wiley. - 1613-6810 .- 1613-6829. ; 16:31
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Tidskriftsartikel (refereegranskat)abstract
- The rational design of catalytically active sites in porous materials is essential in electrocatalysis. Herein, atomically dispersed Fe-N-x sites supported by hierarchically porous carbon membranes are designed to electrocatalyze the hydrazine oxidation reaction (HzOR), one of the key techniques in electrochemical nitrogen transformation. The high intrinsic catalytic activity of the Fe-N-x single-atom catalyst together with the uniquely mixed micro-/macroporous membrane support positions such an electrode among the best-known heteroatom-based carbon anodes for hydrazine fuel cells. Combined with advanced characterization techniques, electrochemical probe experiments, and density functional theory calculation, the pyrrole-type Fe-N-4 structure is identified as the real catalytic site in HzOR.
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| 7. |
- 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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| 8. |
- Li, Xiaoting, et al.
(författare)
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"Mix-Then-On-Demand-Complex" : In Situ Cascade Anionization and Complexation of Graphene Oxide for High-Performance Nanofiltration Membranes
- 2021
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 15:3, s. 4440-4449
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Tidskriftsartikel (refereegranskat)abstract
- Assembling two-dimensional (2D) materials by polyelectrolyte often suffers from inhomogeneous microstructures due to the conventional mixing-and-simultaneous-complexation procedure (mix-and-complex) in aqueous solution. Herein a mix-then-on-demand-complex concept via on-demand in situ cascade anionization and ionic complexation of 2D materials is raised that drastically improves structural order in 2D assemblies, as exemplified by classical graphene oxide (GO)-based ultrathin membranes. Specifically, in dimethyl sulfoxide, the carboxylic acid-functionalized GO sheets (COOH-GOs) were mixed evenly with a cationic poly(ionic liquid) (PIL) and upon filtration formed a well-ordered layered composite membrane with homogeneous distribution of PIL chains in it; next, whenever needed, it was alkali-treated to convert COOH-GO in situ into its anionized state COO--GO that immediately complexed ionically with the surrounding cationic PIL chains. This mix-then-on-demand-complex concept separates the ionic complexation of GO and polyelectrolytes from their mixing step. By synergistically combining the PIL-induced hydrophobic confinement effect and supramolecular interactions, the as-fabricated nanofiltration membranes carry interface transport nanochannels between GO and PIL, reaching a high water permeability of 96.38 L m(-2) h(-1) bar(-1) at a maintained excellent dye rejection 99.79% for 150 h, exceeding the state-of-the-art GO-based hybrid membranes. The molecular dynamics simulations support the experimental data, confirming the interface spacing between GO and PIL as the water transport channels.
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| 9. |
- Li, Yuyang, et al.
(författare)
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A General Carboxylate-Assisted Approach to Boost the ORR Performance of ZIF-Derived Fe/N/C Catalysts for Proton Exchange Membrane Fuel Cells
- 2021
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Ingår i: Advanced Functional Materials. - : Wiley. - 1616-301X .- 1616-3028. ; 31
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Tidskriftsartikel (refereegranskat)abstract
- An Fe/N/C catalyst derived from the pyrolysis of metal-organic frameworks, for example, a zeolitic-imidazolate-framework-8 (ZIF-8), has been regarded as one of the most promising non-precious metal catalysts toward oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs). However, its ORR mass activity is still much inferior to that of Pt, partly because of the lack of general and efficient synthetic strategies. Herein, a general carboxylate-assisted strategy that dramatically enhances the ORR mass activity of ZIF-derived Fe/N/C catalysts is reported. The carboxylate is found to promote the formation of Fe/N/C catalysts with denser accessible active sites and entangled carbon nanotubes, as well as a higher mesoporosity. These structural advantages make the carboxylate-assisted Fe/N/C catalysts show a 2-10 fold higher ORR mass activity than the common carboxylate-free one in various cases. When applied in H-2-O-2 PEMFCs, the active acetate-assisted Fe/N/C catalyst generates a peak power density of 1.33 W cm(-2), a new record of peak power density for a H-2-O-2 PEMFC with non-Pt ORR catalysts.
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| 10. |
- Shao, Yue, et al.
(författare)
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All-Poly(ionic liquid) Membrane-Derived Porous Carbon Membranes : Scalable Synthesis and Application for Photothermal Conversion in Seawater Desalination
- 2018
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 12:11, s. 11704-11710
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Tidskriftsartikel (refereegranskat)abstract
- Herein, we introduce a straightforward, scalable, and technologically relevant strategy to manufacture charged porous polymer membranes (CPMs) in a controllable manner. The pore sizes and porous architectures of CPMs are well-controlled by rational choice of anions in poly(ionic liquid)s (PILs). Continuously, heteroatom-doped hierarchically porous carbon membrane (HCMs) can be readily fabricated via morphology-maintaining carbonization of as-prepared CPMs. These HCMs, as photothermal membranes, exhibited excellent performance for solar seawater desalination, representing a promising strategy to construct advanced functional nanomaterials for portable water production technologies.
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