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Research Article Issue
Covalent triazine frameworks modified by ultrafine Pt nanoparticles for efficient photocatalytic hydrogen production
Nano Research 2024, 17 (6): 4908-4915
Published: 07 February 2024
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Pt nanoparticles (PtNPs) as active species have always been considered as one of the best semiconductor materials for photocatalytic hydrogen production. In this study, a Schottky heterojunction has been successfully constructed by evenly loading ultrafine PtNPs onto a triazine-based covalent organic frameworks (COFs). This strategy maintained the high activity of these ultra-small PtNPs while maximizing the utilization of the Pt active sites. The fabricated PtNPs@covalent triazine-based framework-1 (CTF-1) composite accomplished a significantly high rate of hydrogen evolution (20.0 mmol·g−1·h−1, apparent quantum efficiency (AQE) = 7.6%, at λ = 450 nm) with 0.40 wt.% Pt loading, giving rise to a 44-fold-increase in the efficiency of the photocatalytic hydrogen production compared to the pristine CTF-1. Theoretical calculations revealed that the strong electron transfer (Q(Pt) = −0.726 qe, in the analysis of Bader charge, Q(Pt) is the charge quantity transferred from Pt cluster to CTF-1, and qe is the unit of charge transfer quantity) between PtNPs and CTF-1 triggers a strong interaction, which makes PtNPs being firmly attached to the structure of CTF-1, thereby enabling high stability and excellent hydrogen production efficiency. Importantly, the hydrogen binding free energy (ΔGH*) of PtNPs@CTF-1 is much lower than that of the unmodified CTF-1, leading to a much lower intermediate state and hence a significant improvement in photocatalytic performance. The overall findings of this work provide a new platform to incorporate metallic NPs into COFs for the design and fabrication of highly efficient photocatalysts.

Research Article Issue
Utilization of cationic microporous metal-organic framework for efficient Xe/Kr separation
Nano Research 2022, 15 (8): 7559-7564
Published: 03 June 2022
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The separation of xenon/krypton (Xe/Kr) mixtures plays a vital role in the industrial process of manufacturing high-purity xenon. Compared with energy-intensive cryogenic distillation, porous materials based on physical adsorption are very promising in the low-cost and energy-saving separation processes. Herein, we show that a cationic metal-organic framework (named as FJU-55) exhibits highly efficient Xe/Kr separation performance, which can be attributable to its uniform three-dimensional (3D) interconnection channels and the electro-positive features as the host framework. Moreover, FJU-55 demonstrates good Xe adsorption capacity of 1.41 mmol/g and excellent Xe/Kr selectivity of 10 (298 K and 100 kPa), together with a high Qst value of 39.4 kJ/mol at low coverage area. The superior Xe/Kr separation performance of FJU-55 was further confirmed by the dynamic breakthrough experiments. Results obtained via molecular modeling studies have revealed that the suitable pore size and abundant accessible aromatic ligands in FJU-55 could offer strong multiple C–H∙∙∙Xe interactions, which play a collaborative role in this challenging gas separation task.

Research Article Issue
Metallocorrole-based porous organic polymers as a heterogeneous catalytic nanoplatform for efficient carbon dioxide conversion
Nano Research 2022, 15 (2): 1145-1152
Published: 08 July 2021
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Metallocorrole macrocycles that represent a burgeoning class of attractive metal-complexes from the porphyrinoid family, have attracted great interest in recent years owing to their unique structure and excellent performance revealed in many fields, yet further functionalization through incorporating these motifs into porous nanomaterials employing the bottom-up approach is still scarce and remains synthetically challenging. Here, we report the targeted synthesis of porous organic polymers (POPs) constructed from custom-designed Mn and Fe-corrole complex building units, respectively denoted as CorPOP-1(Mn) and CorPOP-1(FeCl). Specifically, the robust CorPOP-1(Mn) bearing Mn-corrole active centers displays superior heterogeneous catalytic activity toward solvent-free cycloaddition of carbon dioxide (CO2) with epoxides to form cyclic carbonates under mild reaction conditions as compared with the homogeneous counterpart. CorPOP-1(Mn) can be easily recycled and does not show significant loss of reactivity after seven successive cycles. This work highlights the potential of metallocorrole-based porous solid catalysts for targeting CO2 transformations, and would provide a guide for the task-specific development of more corrole-based multifunctional materials for extended applications.

Research Article Issue
De novo synthesis of bifunctional conjugated microporous polymers for synergistic coordination mediated uranium entrapment
Nano Research 2021, 14 (3): 788-796
Published: 01 March 2021
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This work reports a de novo synthesis of novel bifunctional conjugated microporous polymers (CMPs) exhibiting a synergistic-effect involved coordination behavior to uranium. It is highlighted that the synthetic strategy enables the engineering of the coordination environment within amidoxime functionalized CMP frameworks by specifically introducing ortho-substituted amino functionalities, enhancing the affinity to uranyl ions via forming synergistic complexes. The CMPs exhibit high Brunauer-Emmett-Teller (BET) surface area, well-developed three-dimensional (3D) networks with hierarchical porosity, and favorable chemical and thermal stability because of the covalently cross-linked structure. Compared with the amino-free counterparts, the adsorption capacity of bifunctional CMPs was increased by almost 70%, from 105 to 174 mg/g, indicating evidently enhanced binding ability to uranium. Moreover, new insights into coordination mechanism were obtained by in-depth X-ray photoelectron spectroscopy (XPS) analysis and density functional theory (DFT) calculation, suggesting a dominant role of the oxime ligands forming a 1:1 metal ions/ligands (M/L) coordination model with uranyl ions while demonstrating the synergistic engagement of the amino functionalities via direct binding to uranium center and hydrogen-bonding involved secondary-sphere interaction. This work sheds light on the underlying principles of ortho-substituted functionalities directed synergistic effect to promote the coordination of amidoxime with uranyl ions. And the synthetic strategy established here would enable the task-specific development of more novel CMP-based functional materials for broadened applications.

Research Article Issue
Core-satellite metal-organic framework@upconversion nanoparticle superstructures via electrostatic self-assembly for efficient photodynamic theranostics
Nano Research 2020, 13 (12): 3377-3386
Published: 29 August 2020
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The nanoplatforms based on upconversion nanoparticles (UCNPs) have shown great promise in amplified photodynamic therapy (PDT) triggered by near-infrared (NIR) light. However, their practical in vivo applications are hindered by the overheating effect of 980 nm excitation and low utilization of upconversion luminescence (UCL) by photosensitizers. To solve these defects, core-satellite metal-organic framework@UCNP superstructures, composed of a single metal-organic framework (MOF) NP as the core and Nd3+-sensitized UCNPs as the satellites, are designed and synthesized via a facile electrostatic self-assembly strategy. The superstructures realize a high co-loading capacity of chlorin e6 (Ce6) and rose bengal (RB) benefitted from the highly porous nature of MOF NPs, showing a strong spectral overlap between maximum absorption of photosensitizers and emission of UCNPs. The in vitro and in vivo experiments demonstrate that the dual-photosensitizer superstructures have trimodal (magnetic resonance (MR)/UCL/fluorescence (FL)) imaging functions and excellent antitumor effectiveness of PDT at 808 nm NIR light excitation, avoiding the laser irradiation-induced overheating issue. This study provides new insights for the development of highly efficient PDT nanodrugs toward precision theranostics.

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