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1.
Metal phase molybdenum disulfide (1T-MoS2) is considered a promising electrocatalyst for hydrogen evolution reaction (HER) due to its activated basal and superior electrical conductivity. Here, a one-step solvothermal route is developed to prepare 1T-MoS2 with expanded layer spacing through the derivatization of a Mo-based organic framework (Mo-MOFs). Benefiting from N,N-dimethylformamide oxide as external stress, the interplanar spacing of (002) of the MoS2 catalyst is extended to 10.87 Å, which represents the largest one for the 1T-MoS2 catalyst prepared by the bottom-up approach. Theoretical calculations reveal that the expanded crystal planes alter the electronic structure of 1T-MoS2, lower the adsorption–desorption potentials of protons, and thus, trigger efficient catalytic activity for HER. The optimal 1T-MoS2 catalyst exhibits an overpotential of 98 mV at 10 mA cm−2 for HER, corresponding to a Tafel slope of 52 mV dec−1. This Mo-MOFs-derived strategy provides a potential way to design high-performance catalysts by adjusting the layer spacing of 2D materials.  相似文献   

2.
Multivariate metal–organic framework (MOF) is an ideal electrocatalytic material due to the synergistic effect of multiple metal active sites. In this study, a series of ternary M-NiMOF (M = Co, Cu) through a simple self-templated strategy that the Co/Cu MOF isomorphically grows in situ on the surface of NiMOF is designed. Owing to the electron rearrange of adjacent metals, the ternary CoCu-NiMOFs demonstrate the improved intrinsic electrocatalytic activity. At optimized conditions, the ternary Co3Cu-Ni2MOFs nanosheets give the excellent oxygen evolution reaction (OER) performance of current density of 10 mA cm−2 at low overpotential of 288 mV with a Tafel slope of 87 mV dec−1, which is superior to that of bimetallic nanosheet and ternary microflowers. The low free energy change of potential-determining step identifies that the OER process is favorable at Cu–Co concerted sites along with strong synergistic effect of Ni nodes. Partially oxidized metal sites also reduce the electron density, thus accelerating the OER catalytic rate. The self-templated strategy provides a universal tool to design multivariate MOF electrocatalysts for highly efficient energy transduction.  相似文献   

3.
Metal–organic frameworks (MOFs) are an intriguing type of crystalline porous materials that can be readily built from metal ions or clusters and organic linkers. Recently, MOF materials, featuring high surface areas, rich structural tunability, and functional pore surfaces, which can accommodate a variety of guest molecules as proton carriers and to systemically regulate the proton concentration and mobility within the available space, have attracted tremendous attention for their roles as solid electrolytes in fuel cells. Recent advances in MOFs as a versatile platform for proton conduction in the field of humidity condition proton-conduction, anhydrous atmosphere proton-conduction, single-crystal proton-conduction, and including MOF-based membranes for fuel cells, are summarized and highlighted. Furthermore, the challenges, future trends, and prospects of MOF materials for solid electrolytes are also discussed.  相似文献   

4.
The development of sp2-carbon-linked covalent organic frameworks (sp2c-COFs) as artificial photocatalysts for solar-driven conversion of CO2 into chemical feedstock has captured growing attention, but catalytic performance has been significantly limited by their intrinsic organic linkages. Here, a simple, yet efficient approach is reported to improve the CO2 photoreduction on metal-free sp2c-COFs by rationally regulating their intrinsic π-conjugation. The incorporation of ethynyl groups into conjugated skeletons affords a significant improvement in π-conjugation and facilitates the photogenerated charge separation and transfer, thereby boosting the CO2 photoreduction in a solid-gas mode with only water vapor and CO2. The resultant CO production rate reaches as high as 382.0 µmol g−1 h−1, ranking at the top among all additive-free CO2 photoreduction catalysts. The simple modulation approach not only enables to achieve enhanced CO2 reduction performance but also simultaneously gives a rise to extend the understanding of structure-property relationship and offer new possibilities for the development of new π-conjugated COF-based artificial photocatalysts.  相似文献   

5.
Hydrogen, a clean and flexible energy carrier, can be efficiently produced by electrocatalytic water splitting. To accelerate the sluggish hydrogen evolution reaction and oxygen evolution reaction kinetics in the splitting process, highly active electrocatalysts are essential for lowering the energy barriers, thereby improving the efficiency of overall water splitting. Combining the distinctive advantages of metal–organic frameworks (MOFs) with the physicochemical properties of 2D materials such as large surface area, tunable structure, accessible active sites, and enhanced conductivity, 2D MOFs have attracted intensive attention in the field of electrocatalysis. Different strategies, such as improving the conductivities of MOFs, reducing the thicknesses of MOF nanosheets, and integrating MOFs with conductive particles or substrates, are developed to promote the catalytic performances of pristine MOFs. This review summarizes the recent advances of pristine 2D MOF-based electrocatalysts for water electrolysis. In particular, their intrinsic electrocatalytic properties are detailly analyzed to reveal important roles of inherent MOF active centers, or other in situ generated active phases from MOFs responsible for the catalytic reactions. Finally, the challenges and development prospects of pristine 2D MOFs for the future applications in overall water splitting are discussed.  相似文献   

6.
Metal–organic frameworks (MOFs) have received much attention as a solid-state electrolyte in proton exchange membrane fuel cells. The introduction of proton carriers and functional groups into MOFs can improve the proton conductivity attributed to the formation of hydrogen-bonding networks, while the underlying synergistic mechanism is still unclear. Here, a series of flexible MOFs (MIL-88B, [Fe3O(OH)(H2O)2(O2C-C6H4-CO2)3] with imidazole) is designed to modify the hydrogen-bonding networks and investigate the resulting proton-conducting characteristics by controlling the breathing behaviors. The breathing behavior is tuned by varying the amount of adsorbed imidazole into pore (small breathing (SB) and large breathing (LB)) and introducing functional groups onto ligands (-NH2, -SO3H), resulting in four kinds of imidazole-loaded MOFs−Im@MIL-88B-SB, Im@MIL-88B-LB, Im@MIL-88B-NH2, and Im@MIL-88B-SO3H. Im@MIL-88B-LB without functional groups exhibits the highest proton conductivity of 8.93 × 10−2 S cm−1 at 60 °C and 95% relative humidity among imidazole-loaded proton conductors despite the mild condition, indicating that functional groups may not be always required to enhance proton conductivity. The elaborately controlled pore size and host–guest interaction in flexible MOFs through imidazole-dependent structural transformation are translated into the high proton concentration without the limitation of proton mobility, contributing to the formation of effective hydrogen-bonding networks in imidazole conducting media.  相似文献   

7.
Rechargeable sodium–iodine (Na–I2) batteries are attracting growing attention for grid-scale energy storage due to their abundant resources, low cost, environmental friendliness, high theoretical capacity (211 mAh g−1), and excellent electrochemical reversibility. Nevertheless, the practical application of Na–I2 batteries is severely hindered by their poor cycle stability owing to the serious dissolution of polyiodide in the electrolyte during charge/discharge processes. Herein, the atomic modulation of metal–bis(dihydroxy) species in a fully conjugated phthalocyanine copper metal–organic framework (MOF) for suppression of polyiodide dissolution toward long-time cycling Na–I2 batteries is demonstrated. The Fe2[(2,3,9,10,16,17,23,24-octahydroxy phthalocyaninato)Cu] MOF composited with I2 (Fe2–O8–PcCu/I2) serves as a cathode for a Na–I2 battery exhibiting a stable specific capacity of 150 mAh g−1 after 3200 cycles and outperforming the state-of-the-art cathodes for Na–I2 batteries. Operando spectroelectrochemical and electrochemical kinetics analyses together with density functional theory calculations reveal that the square planar iron–bis(dihydroxy) (Fe–O4) species in Fe2–O8–PcCu are responsible for the binding of polyiodide to restrain its dissolution into electrolyte. Besides the monovalent Na–I2 batteries in organic electrolytes, the Fe2–O8–PcCu/I2 cathode also operates stably in other metal–I2 batteries like aqueous multivalent Zn–I2 batteries. Thus, this work offers a new strategy for designing stable cathode materials toward high-performance metal–iodine batteries.  相似文献   

8.
Optimizing catalysts for competitive photocatalytic reactions demand individually tailored band structure as well as intertwined interactions of light absorption, reaction activity, mass, and charge transport.  Here, a nanoparticulate host–guest structure is rationally designed that can exclusively fulfil and ideally control the aforestated uncompromising requisites for catalytic reactions. The all-inclusive model catalyst consists of porous Co3O4 host and ZnxCd1-xS guest with controllable physicochemical properties enabled by self-assembled hybrid structure and continuously amenable band gap. The effective porous topology nanoassembly, both at the exterior and the interior pores of a porous metal–organic framework (MOF), maximizes spatially immobilized semiconductor nanoparticles toward high utilization of particulate heterojunctions for vital charge and reactant transfer. In conjunction, the zinc constituent band engineering is found to regulate the light/molecules absorption, band structure, and specific reaction intermediates energy to attain high photocatalytic CO2 reduction selectivity. The optimal catalyst exhibits a H2-generation rate up to 6720 µmol g−1 h−1 and a CO production rate of 19.3 µmol g−1 h−1. These findings provide insight into the design of discrete host–guest MOF-semiconductor hybrid system with readily modulated band structures and well-constructed heterojunctions for selective solar-to-chemical conversion.  相似文献   

9.
The unparalleled theoretical specific energy of lithium–sulfur (Li–S) batteries has attracted considerable research interest from within the battery community. However, most of the long cycling results attained thus far relies on using a large amount of electrolyte in the cell, which adversely affects the specific energy of Li–S batteries. This shortcoming originates from the low solubility of polysulfides in the electrolyte. Here, 1,3-dimethyl-2-imidazolidinone (DMI) is reported as a new high donor electrolyte for Li–S batteries. The high solubility of polysulfides in DMI and its activation of a new reaction route, which engages the sulfur radical (S3•−), enables the efficient utilization of sulfur as reflected in the specific capacity of 1595 mAh g−1 under lean electrolyte conditions of 5 μLelectrolyte mgsulfur−1. Moreover, the addition of LiNO3 stabilizes the lithium metal interface, thereby elevating the cycling performance to one of the highest known for high donor electrolytes in Li–S cells. These engineered high donor electrolytes are expected to advance Li–S batteries to cover a wide range of practical applications, particularly by incorporating established strategies to realize the reversibility of lithium metal electrodes.  相似文献   

10.
Extensive efforts have been devoted to the design of organic photothermal agents (PTAs) that absorb in the second near-infrared (NIR-II) bio-window, which can provide deeper tissue penetration that is significant for phototheranostics of lethal brain tumors. Herein, the first example of NIR-II-absorbing small organic molecule (N1) derived from perylene monoamide (PMI) and its bio-application after nano-encapsulation of N1 to function as a nano-agent for phototheranostics of deep orthotopic glioblastoma (GBM) is reported. By adopting a dual modification strategy of introducing a donor-acceptor unit and extending π-conjugation, the obtained N1 can absorb in 1000–1400 nm region and exhibit high photothermal conversation due to the apparent intramolecular charge transfer (ICT). A choline analogue, 2-methacryloyloxyethyl phosphorylcholine, capable of interacting specifically with receptors on the surface of the blood-brain barrier (BBB), is used to fabricate the amphiphilic copolymer for the nano-encapsulation of N1. The obtained nanoparticles demonstrate efficient BBB-crossing due to the receptor-mediated transcytosis as well as the small nanoparticle size of approximately 26 nm. The prepared nanoparticles exhibit excellent photoacoustic imaging and significant growth inhibition of deep orthotopic GBM. The current study demonstrates the enormous potential of PMI-based NIR-II PTAs and provides an efficient phototheranostic paradigm for deep orthotopic GBM.  相似文献   

11.
The isotope effect is studied in the magneto-electroluminescence (MEL) and pulsed electrically detected magnetic resonance of organic light-emitting diodes based on thermally activated delayed fluorescence (TADF) from donor–acceptor exciplexes that are either protonated (H) or deuterated (D). It is found that at ambient temperature, the exchange of H to D has no effect on the spin-dependent current and MEL responses in the devices. However, at cryogenic temperatures, where the reverse intersystem crossing (RISC) from triplet to singlet exciplex diminishes, a pronounced isotope effect is observed. These results show that the RISC process is not governed by the hyperfine interaction as thought previously, but proceeds through spin-mixing in the triplet exciplex. The observations are corroborated by electrically detected transient spin nutation experiments that show relatively long dephasing time at ambient temperature, and interpreted in the context of a model that involves exchange and hyperfine interactions in the spin triplet exciplex. These findings deepen the understanding of the RISC process in TADF materials.  相似文献   

12.
Molecular catalysts have been receiving increasingly attention in the electrochemical CO2 reduction reaction (CO2RR) with attractive features such as precise catalytic sites and tunable ligands. However, the insufficient activity and low selectivity of deep reduction products restrain the utilization of molecular catalysts in CO2RR. Herein, a donor–acceptor modified Cu porphyrin (CuTAPP) is developed, in which amino groups are linked to donate electrons toward the central CuN4 site to enhance the CO2RR activity. The CuTAPP catalyst exhibited an excellent CO2-to-CH4 electroreduction performance, including a high CH4 partial current density of 290.5 mA cm−2 and a corresponding Faradaic efficiency of 54.8% at –1.63 V versus reversible hydrogen electrode in flow cells. Density functional theory calculations indicated that CuTAPP presented a much lower energy gap in the pathway of producing *CHO than Cu porphyrin without amino group modification. This work suggests a useful strategy of introducing designed donor–acceptor structures into molecular catalysts for enhancing electrochemical CO2 conversion toward deep reduction products.  相似文献   

13.
Metal–organic frameworks (MOFs) and their derivatives have attracted much attention in the field of photo/electrocatalysis owing to their ultrahigh porosity, tunable properties, and superior coordination ability. Regulating the valence electronic structure and coordination environment of MOFs is an effective way to enhance their intrinsic catalytic performance. Rare earth (RE) elements with 4f orbital occupancy provide an opportunity to evoke electron rearrangement, accelerate charged carrier transport, and synergize the surface adsorption of catalysts. Therefore, the integration of RE with MOFs makes it possible to optimize their electronic structure and coordination environment, resulting in enhanced catalytic performance. In this review, progress in current research on the use of RE-modified MOFs and their derivatives for photo/electrocatalysis is summarized and discussed. First, the theoretical advantages of RE in MOF modification are introduced, with a focus on the roles of 4f orbital occupancy and RE ion organic coordination ligands. Then, the application of RE-modified MOFs and their derivatives in photo/electrocatalysis is systematically discussed. Finally, research challenges, future opportunities, and prospects for RE-MOFs are also discussed.  相似文献   

14.
Electrocatalysis is a highly promising technology widely used in clean energy conversion. There is a continuing need to develop advanced electrocatalysts to catalyze the critical electrochemical reactions. Integrating metal active species, including various metal nanostructures (NSs) and atomically dispersed metal sites (ADMSs), into metal–organic frameworks (MOFs) leads to the formation of promising heterogeneous electrocatalysts that take advantage of both components. Among them, MOFs can provide support and protection for the active sites on guest metals, and the resulting host-guest interactions can synergistically enhance the electrocatalytic performance. In this review, three key concerns on MOF-metal heterogeneous electrocatalysts regarding the catalytic sites, conductivity, and catalytic stability are first presented. Then, rational integration strategies of MOFs and metals, including the integration of metal NSs via surface anchoring, space confining, and MOF coating, as well as the integration of ADMSs either with the metal nodes/linkers or within the pores of MOFs, along with their recent progress on synergistic cooperation for specific electrochemical reactions are summarized. Finally, current challenges and possible solutions in applying these increasingly concerned electrocatalysts are also provided.  相似文献   

15.
Bacterial infections pose a significant threat to global public health; therefore, the development of novel therapeutics is urgently needed. Herein, a controllable antibacterial nanoplatform utilizing cyclodextrin metal–organic frameworks (CD-MOFs) as a template to synthesize ultrafine silver nanoparticles (Ag NPs) in their porous structure is constructed. Subsequently, polydopamine (PDA) is encapsulated on the CD-MOFs’ surface via dopamine polymerization to enhance the water stability and enable hyperthermia capacity. The resulting Ag@MOF@PDA generates localized hyperthermia and gradually releases Ag+ to achieve long-term photothermal-chemical bactericidal capability. The release rate of Ag+ can be accelerated by NIR-mediated heating in a controllable manner, quickly reaching the effective concentration and reducing the frequency of medication to avoid potential toxicity. In vitro experiments demonstrate that the combined antibacterial strategy can not only effectively kill both gram-negative and gram-positive bacteria, but also directly eradicate mature biofilms. In vivo results confirm that both bacterial- and biofilm-infected wounds treated with a combination of Ag@MOF@PDA and laser exhibit satisfactory recovery with minimal toxicity, displaying a superior therapeutic effect compared to other groups. Together, the results warrant that the Ag@MOF@PDA realizes synergistic antibacterial capacity and controllable release of Ag+ to combat bacterial and biofilm infections, providing a potential antibiotic-free alternative in the “post-antibiotic era.”  相似文献   

16.
The separation of hydrocarbons is of primary importance in the petrochemical industry but remains a challenging process. Hydrocarbon separations have traditionally relied predominantly on costly and energy-intensive heat-driven procedures such as low-temperature distillations. Adsorptive separation based on porous solids represents an alternative technology that is potentially more energy efficient for the separation of some hydrocarbons. Great efforts have been made recently not only in the development of adsorbents with optimal separation performance but also toward the subsequent implementation of adsorption-based separation technology. Emerging as a relatively new class of multifunctional porous materials, metal–organic frameworks (MOFs) hold substantial promise as adsorbents for highly efficient separation of hydrocarbons. This is because of their exceptional and intrinsic porosity tunability, which enables size-exclusion-based separations that render the highest possible separation selectivity. In this review, recent advances in the development of MOFs for separation of selected groups of hydrocarbons are reviewed, including methane/C2 hydrocarbons, normal alkanes, alkane isomers, and alkane/alkene/alkyne and C8 alkylaromatics, with a particular focus on separations based on the size-exclusion mechanism. Insights into tailor-made structures, material design strategies, and structure–property relationships will be elucidated. In addition, the existing challenges and possible future directions of this important research field will be discussed.  相似文献   

17.
Urea oxidation reaction (UOR) is one of the promising alternative anodic reactions to water oxidation that has attracted extensive attention in green hydrogen production. The application of specifically designed electrocatalysts capable of declining energy consumption and environmental consequences is one of the major challenges in this field. Therefore, the goal is to achieve a resistant, low-cost, and environmentally friendly electrocatalyst. Herein, a water-stable fluorinated Cu(II) metalorganic framework (MOF) {[Cu2(L)(H2O)2]·(5DMF)(4H2O)}n (Cu-FMOF-NH2; H4L = 3,5-bis(2,4-dicarboxylic acid)-4-(trifluoromethyl)aniline) is developed utilizing an angular tetracarboxylic acid ligand that incorporates both trifluoromethyl (–CF3) and amine (–NH2) groups. The tailored structure of Cu-FMOF-NH2 where linkers are connected by fluoride bridges and surrounded by dicopper nodes reveals a 4,24T1 topology. When employed as electrocatalyst, Cu-FMOF-NH2 requires only 1.31 V versus reversible hydrogen electrode (RHE) to deliver 10 mA cm−2 current density in 1.0 m KOH with 0.33 m urea electrolyte and delivered an even higher current density (50 mA cm−2) at 1.47 V versus RHE. This performance is superior to several reported catalysts including commercial RuO2 catalyst with overpotential of 1.52 V versus RHE. This investigation opens new opportunities to develop and utilize pristine MOFs as a potential electrocatalyst for various catalytic reactions.  相似文献   

18.
Three linear isoelectronic conjugated polymers PCC , PBC , and PBN are synthesized by Suzuki-Miyaura polycondensation for photocatalytic hydrogen (H2) production from water. PBN presented an excellent photocatalytic hydrogen evolution rate (HER) of 223.5 µmol h−1 (AQY420 = 23.3%) under visible light irradiation, which is 7 times that of PBC and 31 times that of PCC . The enhanced photocatalytic activity of PBN is due to the improved charge separation and transport of photo-induced electrons/holes originating from the lower exciton binding energy (Eb), longer fluorescence lifetime, and stronger built-in electric field, caused by the introduction of the polar B←N unit into the polymer backbone. Moreover, the extension of the visible light absorption region and the enhancement of surface catalytic ability further increase the activity of PBN . This work reveals the potential of B←N fused structures as building blocks as well as proposes a rational design strategy for achieving high photocatalytic performance.  相似文献   

19.
Metal–organic frameworks(MOFs)with high microporosity and relatively high thermal stability are potential thermal insulation and flame-retardant materials.However,the difficulties in processing and shaping MOFs have largely hampered their applications in these areas.This study outlines the fabrication of hybrid CNF@MOF aerogels by a stepwise assembly approach involving the coating and cross-linking of cellulose nanofibers(CNFs)with continuous nanolayers of MOFs.The cross-linking gives the aerogels high mechanical strength but superelasticity(80%maximum recoverable strain,high specific compression modulus of^200 MPa cm3 g−1,and specific stress of^100 MPa cm3 g−1).The resultant lightweight aerogels have a cellular network structure and hierarchical porosity,which render the aerogels with relatively low thermal conductivity of^40 mW m−1 K−1.The hydrophobic,thermally stable MOF nanolayers wrapped around the CNFs result in good moisture resistance and fire retardancy.This study demonstrates that MOFs can be used as efficient thermal insulation and flame-retardant materials.It presents a pathway for the design of thermally insulating,superelastic fire-retardant nanocomposites based on MOFs and nanocellulose.  相似文献   

20.
Hierarchically ordered porous materials with tailored and inter-connected macro-, meso-, and micro-pores would facilitate the heterogeneous adsorption and catalysis processes for a wide range of applications but remain a challenge for synthetic chemists. Here, a general and efficient strategy for the synthesis of inverse opal metal–organic frameworks (IO MOFs) with a tunable size of macro-, meso-, and micro-pores is reported. The strategy is based on the step-wise template formation, precursor infiltration, solvo-thermal reaction, and chemical etching. As a proof of the general applicability of this strategy, a series of inverse opal zirconium-based MOFs with intrinsic micro- and/or meso-pores, including UiO-66, MOF-808, NU-1200, NU-1000 and PCN-777, and tunable macropores (1 µm, 2 µm, 3 µm, 5 µm, and 10 µm), have been prepared with outstanding yields. These IO MOFs demonstrate significantly enhanced absorption rates and faster initial hydrolysis rates for organophosphorus (OPs) aggregates compared to those of the pristine MOFs. This work paves the way for the further development of hierarchically ordered MOFs for advanced applications.  相似文献   

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