Hierarchical porosity and functionalization help to fully make use of metal–organic frameworks (MOFs) for their diverse applications. Herein, a simple strategy is reported to construct hierarchically ...porous MOFs through a competitive coordination method using tetrafluoroborate (M(BF4)x, where M is metal site) as both functional sites and etching agents. The resulting MOFs have in situ formed defect‐mesopores and functional sites without sacrificing their structure stability. The formation mechanism of the defect‐mesopores is elucidated by a combination of experimental and first‐principles calculation method, indicating the general feasibility of this new approach. Compared with the original microporous counterparts, the new hierarchical MOFs exhibit superior adsorption for the bulky dye molecules and catalytic performance for the CO2 conversion attributed to their specific hierarchical pore structures.
A simple and novel strategy is reported to fabricate a series of hierarchically porous metal–organic frameworks through the competitive coordination method. The formation mechanism of defect‐mesopores is elucidated by a combination of experimental and first‐principles calculation methods. Furthermore, the adsorption and catalytic advantage over the original microporous counterparts is also demonstrated attributed to their specific hierarchical pore structures.
The homojunction of oxygen/metal vacancies and its interfacial n–p effect on the physiochemical properties are rarely reported. Interfacial n–p homojunctions of TiO2 are fabricated by directly ...decorating interfacial p‐type titanium‐defected TiO2 around n‐type oxygen‐defected TiO2 nanocrystals in amorphous–anatase homogeneous nanostructures. Experimental measurements and theoretical calculations on the cell lattice parameters show that the homojunction of oxygen and titanium vacancies changes the charge density of TiO2; a strong EPR signal caused by oxygen vacancies and an unreported strong titanium vacancies signal of 2D 1H TQ‐SQ MAS NMR are present. Amorphous–anatase TiO2 shows significant performance regarding the photogeneration current, photocatalysis, and energy storage, owing to interfacial n‐type to p‐type conductivity with high charge mobility and less structural confinement of amorphous clusters. A new “homojunction of oxygen and titanium vacancies” concept, characteristics, and mechanism are proposed at an atomic‐/nanoscale to clarify the generation of oxygen vacancies and titanium vacancies as well as the interface electron transfer.
The homojunction of oxygen and titanium vacancies developed in the amorphous–anatase interface of nanostructured TiO2 results in a unique n–p electronic transmission, which is mostly preferred to the mobility of electronic charge carriers. It also contributes to significant performance regarding photogeneration current, photocatalysis, and energy storage.
Hierarchies design of porosity in metal‐organic frameworks (MOFs) has gained significant interest in recent years, and customization of mesoporous sizes in MOFs is still quite challenging. Herein, a ...template‐free method by nucleation‐competition has been developed to realize a near‐linear control of the mesopore sizes (3–13 nm) in the hierarchical MOF UiO‐66(Hf). High selectivity of enzyme adsorption, high activity of bulky‐molecular catalysis, high stability of mesostructure, and extension to other MOFs further prove the success in the potential customization synthesis and applications.
A template‐free method by nucleation‐competition has been developed to realize near‐linear control of the mesopore sizes (3–13 nm) in the hierarchical metal‐organic frameworks UiO‐66(Hf), showing significant performances regarding molecular selectivity, catalytic activity, and mesostructure stability.
Alloying platinum (Pt) with transition metals (M), as an established class of electrocatalysts, reduces the use of Pt and improves the electrocatalytic performance. However, the stability of ...transition metals in nanostructured platinum alloys is a fundamental and practical problem in electrocatalysis, due to leaching of transition metals under acidic operating condition. Here, a corrosion method has been developed for a Pt−Cu electrocatalyst with high activity (6.6 times that of commercial Pt/C) and excellent stability for the methanol oxidation reaction (MOR) under acidic operating conditions. The mechanism of formation has been studied, and possible mesostructured re‐formation and atomic re‐organization have been proposed. This work offers an effective strategy for the facile synthesis of a highly acid‐stable PtM alloying and opens a door to high‐performance design for electrocatalysts.
Acid tested: An ultimate corrosion method to Pt−Cu electrocatalysts is presented that greatly promotes electrocatalytic activity and stability for methanol oxidation under acidic conditions. The formation mechanism has been investigated, and a mesostructured re‐formation and atomic re‐organization process is proposed. Our method could potentially be extended to the facile synthesis of highly acid stable Pt‐based alloys with excellent electrocatalytic performance.
Carbon‐based nanomaterials have been widely utilized in catalysis and energy‐related fields due to their fascinating properties. However, the controllable synthesis of porous carbon with refined ...morphology is still a formidable challenge due to inevitable aggregation/fusion of resulted carbon particles during the high‐temperature synthetic process. Herein, a hierarchically oriented carbon‐structured (fiber‐like) composite is fabricated by simultaneously taking advantage of a confined pyrolysis strategy and disparate bond environments within metal–organic frameworks (MOFs). In the resultant composite, the oriented carbon provides a fast mass (molecule/ion/electron) transfer efficiency; the doping‐N atoms can anchor or act as active sites; the mesoporous SiO2 (mSiO2) shell not only effectively prevents the derived carbon or active metal nanoparticles (NPs) from aggregation or leaching, but also acts as a “polysulfide reservoir” in the Li–S batteries to suppress the “shuttle” effect. Benefiting from these advantages, the synthesized composite Pd@NDHPC@mSiO2 (NDHPC means N‐doped hierarchically porous carbon) exhibits extremely high catalytic activity and stability toward the one‐pot Knoevenagel condensation–hydrogenation reaction. Furthermore, the oriented NDHPC@mSiO2 manifests a boosted capacity and cycling stability in Li–S batteries compared to the counterpart that directly pyrolyzes without silica protection. This report provides an effective strategy of fabricating hierarchically oriented carbon composites for catalysis and energy storage applications.
An N‐doped oriented carbon‐structured (fiber‐like) composite with hierarchical pore and ultrafine Pd nanoclusters is fabricated by simultaneously taking advantage of the confined pyrolysis strategy and disparate bond environments within metal–organic frameworks (MOFs). The synthesized composite Pd@NDHPC@mSiO2 manifests extremely high catalytic activity toward tandem catalysis and much boosted cycling stability in Li–S batteries.
Polyethylene terephthalate (PET) is the most widely used polymer in the world. For the first time, the laser‐driven integration of aluminum nanoparticles (Al NPs) into PET to realize a laser‐induced ...graphene/Al NPs/polymer composite, which demonstrates excellent toughness and high electrical conductivity with the formation of aluminum carbide into the polymer is shown. The conductive structures show an impressive mechanical resistance against >10000 bending cycles, projectile impact, hammering, abrasion, and structural and chemical stability when in contact with different solvents (ethanol, water, and aqueous electrolytes). Devices including thermal heaters, carbon electrodes for energy storage, electrochemical and bending sensors show this technology's practical application for ultra‐robust polymer electronics. This laser‐based technology can be extended to integrating other nanomaterials and create hybrid graphene‐based structures with excellent properties in a wide range of flexible electronics’ applications.
Taking circuits and sensors from their conventional rigid nature to flexible architectures is an unavoidable step for the future of electronics. Here, the inexpensive and large‐scale laser‐driven fabrication of circuits on the surface of common plastic materials is shown. The results show a strong integration of nanoparticles with simultaneous graphene formation for high‐performance flexible electronics.
Hierarchically dual‐mesoporous TiO2 microspheres have been synthesized by a solvothermal process in the presence of 1‐butyl‐3‐methylimidazolium tetrafluoroborate (BMImBF4) and diethylenetriamine ...(DETA) as co‐templates. Secondary mesostructured defects in the hierarchical TiO2 microspheres produce oxygen vacancies, which not only significantly enhance photocatalytic activity in the degradation of methylene blue (1.7 times that with P25) and acetone (2.9 times that with P25), but are also beneficial for lithium storage. Moreover, we propose a mechanism to rationalize the role of this dual mesoporosity of the TiO2 microspheres in enhancing molecular diffusion, ion transportation, and electronic transitions.
Beneficial dual mesoporosity: Hierarchically dual‐mesoporous TiO2 has been synthesized by a co‐templating method. Its mesostructured defects caused by an ionic liquid lead to a high level of oxygen vacancies (see graphic), which significantly enhance its photoelectrochemical performance.
A ratiometric fluorescence sensor for sensitive and selective dopamine detection based on carbon dots-gold nanoclusters hybrid
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•A ratiometric fluorescence sensor based on CDots-AuNCs ...hybrid was designed for dopamine detection.•The sensor provided remarkable ratiometric fluorescence intensity change.•The sensor exhibited excellent sensitivity and selectivity.•Human serum samples were analyzed.
In this work, a novel fluorescence resonance energy transfer (FRET)-based ratiometric fluorescent probe, carbon dots-gold nanoclusters hybrid (CDots-AuNCs), was fabricated for selective, sensitive and reliable sensing of dopamine (DA). This FRET probe is comprised of a two-fluorophore, where carbon dots (CDots) serve as the energy donor and gold nanoclusters (AuNCs) as the acceptor, with dual emission peaks at 420 nm and 610 nm under a single excitation wavelength of 380 nm. The addition of DA to this probe solution resulted in the fluorescence at 610 nm quenching, while the blue fluorescence at 420 nm recovering. By monitoring the change of ratiometric fluorescent intensity at 420 and 610 nm, the DA could be detected with the range from 5 to 180 nM and a limit of detection around 2.9 nM. Finally, the developed sensing method was successfully applied to DA determination in serum samples with satisfactory recoveries in the range of 95%–105%.
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