Dodecahedral Morphology Research Articles

Performance of xMg3Al1-LDH@ZIF-8 in High Efficiency Electrocatalytic Reduction of CO2 to CO.

This study involves the preparation of the precursor of magnesium aluminum layered double hydroxide (Mg3Al1-LDH) through a hydrothermal synthesis method. Subsequently, altering the loading amount of the precursor to synthesize a series of nanomaterials (xMg3Al1-LDH@ZIF-8, x = 0.2, 0.5, and 0.8) composite with zeolitic imidazolate framework-8 (ZIF-8). The investigation delves into the electrocatalytic performance of the material in the electrochemical reduction of CO2 (CO2RR) for the production of CO. The electrocatalyst is subjected to analysis through various techniques such as XRD, XPS, Raman, FTIR, SEM, EDS, TEM, BET, etc., to examine the elemental composition, microscopic morphology, and surface area with pore size. The electrochemical performance of the materials is tested and analyzed using an electrochemical workstation and gas chromatograph. The research findings reveal that the electrocatalyst with a loading amount of 0.5 g, denoted as 0.5Mg3Al1-LDH@ZIF-8, exhibits a well-defined rhombic dodecahedral morphology with a surface-attached layered structure. This structure, characterized by relatively strong interactions, provides abundant active sites for the reaction, consequently demonstrating superior electrochemical performance. The Faradaic efficiency (CO FE) for CO2RR to produce CO reaches a maximum of 88.08% at -1.5 V vs. RHE. Maintaining a constant applied voltage at -1.4 V vs. RHE ensures stability for up to 4 h.

Enhanced ammonia yield rate from nitrogen on collapsed dodecahedral-shaped Co/NC electrocatalyst

Nowadays, multi-component non-precious metal catalysts have been considered as a significant strategy for enhancing the yield of synthesizing NH3 by electrocatalytic nitrogen reduction reaction (E-NRR). In the present work, carbon composites doped with well-dispersed Co and N (Co/NC) were prepared by pyrolyzing zeolitic imidazolate framework-67 (ZIF-67) at various temperatures protected under a N2 flow. Co/NC exhibits a collapsed dodecahedral morphology with a mesoporous structure (3.5–4 nm). The chemical states of Co/N and the structural defects of C are closely related to the carbonization temperature. In a N2-saturated 0.1 M KOH electrolyte, the as-prepared catalysts exhibit an NH3 yield rate (Y(NH3)) of 60.57 μg h-1 mgcat.-1 and a Faradaic efficiency (FE) of 23.3 % at -0.1 V (vs the reversible hydrogen electrode, RHE) at ambient conditions. The enhanced E-NRR activity of Co/NC may primarily originate from an associative distal pathway on the Co-N3C sites and the carbon defects in an alkaline electrolyte. Specifically, this work presents a three-component E-NRR catalyst with excellent stability and great activity based on Co/NC.

ZIF-8-derived carbon substrates embedded with atomically dispersed FeN2O2 active sites as bifunctional catalysts for electrochemical carbon dioxide and oxygen reduction

Transition metal assemblies on nitrogen-containing carbon substrates have promising applications as bifunctional electrocatalysts for electrochemical carbon dioxide reduction reaction (CO2RR) and oxygen reduction reaction (ORR). In this study, ZIF-8 with a rhombic dodecahedral morphology was grown from zinc nitrate and 2-methylimidazole feedstock. Then, a nitrogen-containing carbon substrate with a pore structure was formed after the release of Zn through high-temperature calcination. During the calcination process at 700°C, Fe atoms were physically adsorbed on the nitrogen-containing carbon substrate and ligated with N/O to form FeN2O2 reactive sites. For CO2RR, FeN2O2/NC exhibited excellent catalytic properties for converting CO2 to CO, achieving a high Faraday efficiency of 95.5 % at −0.7 V. Under alkaline conditions, it demonstrated ORR performance (E1/2 = 0.83 V) comparable with that of Pt/C (E1/2 = 0.82 V). This study not only presents an energy-efficient method for CO2RR but also provides new insights into highly active catalysts for ORR.

Green synthesis of ZIF-67 nanoparticles via microfluidics: Towards sustainable nanomaterial production

This study explored the synthesis of zeolitic imidazolate framework-67 (ZIF-67) nanoparticles using a microfluidic reactor, focusing on the effects of reactant concentration, temperature, and flow rate on the material’s properties. Design Expert software was utilized to optimize these variables to enhance the synthesis process while preventing reactor clogging due to precipitate formation. The experiments varied concentrations of cobalt (II) nitrate hexahydrate and 2-methylimidazole, along with temperature and flow rates. After synthesis, the samples underwent extensive characterization, including FTIR, NMR, TEM, SAED, and XRD analyses. FTIR results confirmed the successful formation of ZIF-67, with varying conditions leading to shifts in peak positions and intensities, indicating changes in bonding and molecular structure. NMR spectra provided insights into the hydrogen environments within the nanoparticles. TEM and SAED analyses revealed that the nanoparticles predominantly exhibited a uniform rhombic dodecahedral morphology with diameters ranging from 5 to 10 nm. XRD patterns were consistent with simulated data, showing variations in peak positions and crystallinity with changes in synthesis conditions. The study highlighted that increasing reactant concentrations, temperature, and flow rate generally enhanced the production rate and crystallinity of ZIF-67, with 2-methylimidazole concentration having the most significant impact. The findings contributed to optimizing ZIF-67 synthesis, demonstrating the feasibility of using microfluidic reactors and green solvents for producing high-quality nanoparticles with controlled properties.

Cobalt-Copper-Embedded Nitrogen-Doped Carbon Nanostructures Derived from Zeolite Imidazolate Frameworks as Electrocatalysts for the Oxygen Reduction Reaction.

In recent years, researchers have focused on developing zeolite imidazolate frameworks (ZIFs) as an alternative to Pt electrocatalysts for various applications, including water splitting, lithium-air batteries, zinc-air batteries, and fuel cells. In this study, we synthesized CoCu-ZIF to be used as a precursor in the development of cathode catalysts for the oxygen reduction reaction (ORR) in fuel cells. Hydrazine played a crucial role in maintaining uniformity in the development and particle size of the ZIF-67 structures. Moreover, it facilitated the rapid formation of the ZIF-67 structures at higher temperatures. A unique pseudorhombic dodecahedral morphology was obtained at a Co/Cu molar ratio of 7:3. Among all the synthesized N-doped carbon nanostructures embedded with Co and Cu nanoparticles, CoCu@NC-750, pyrolyzed at 750 °C, showed superior ORR catalytic performance. This catalyst exhibited a notably higher half-wave potential of 0.816 V and demonstrated a clear 4-electron transfer mechanism. The overpotential of CoCu@NC-750 shifted by only 11 mV over 10,000 cyclic voltammetry cycles, whereas a 55 mV shift was observed for Pt/C. CoCu@NC-750 exhibited a ∼0.8% decrease in current density during a 12-h ORR, in contrast to the 8.3% decline shown by Pt/C. This superior catalytic activity and stability can be attributed to factors such as higher oxygen adsorption induced by the N-doped carbon layer due to the localized changes in electron density and the enhanced stability of the bimetallic core. Our findings suggest that CoCu@NC-750 is a promising alternative to Pt/C in fuel cell cathodes.

Preparation of Ni, Co doped hollow carbon nanocage from core-shell structure ZIF-8@ZIF-67 for nitrobenzene monitoring

Herein, we employed a Ni, Co duplex metal-doped hollow carbon nanocage derived from the core-shell Zeolite imidazole framework-8 (Zn)@Zeolite imidazole framework-67 (Co) (ZIF-8@ZIF-67) for the sensitive electrochemical detection of nitrobenzene (NB). The precursor was created by coating ZIF-67 on the surface of ZIF-8 through the epitaxial growth method, followed by Ni doping. Subsequent pyrolysis resulted in the formation of a Ni, Co duplex metal-doped hollow carbon nanocage. Characterization of the nanocomposite confirmed the unique hollow and porous structure of NiCo/C, maintaining a dodecahedral morphology with a uniform distribution of carbon and transition metal nanoparticles. The NiCo/C-modified electrode exhibits a wide linear dynamic range (0.05–11.22 μM and 11.22–230.06 μM), a lower limit of detection (0.14 μM), superior stability and selectivity for the detection of NB. Moreover, it shows appropriate practicality toward detecting NB in natural water samples.

Acidic Environment-Responsive Metal Organic Framework-Mediated Dihydroartemisinin Delivery for Triggering Production of Reactive Oxygen Species in Drug-Resistant Lung Cancer.

Dihydroartemisinin (DHA) has emerged as a promising candidate for anticancer therapy. However, the application of DHA in clinics has been hampered by several limitations including poor bioavailability, short circulation life, and low solubility, significantly restricting its therapeutic efficacy and leading to notable side effects during the treatment. We present DHA-loaded zeolitic imidazolate framework-8 (D-ZIF) with controllable and targeted DHA release properties, leading to enhanced antitumor effects while reducing potential side effects. D-ZIF was prepared by one-pot synthesis method using methylimidazole (MIM), Zn(NO3)2•6H2O and DHA. We characterized the physical and chemical properties of D-ZIF by TEM, DLS, XRD, FT-IR, and TG. We measured the drug loading efficiency and the cumulative release of DHA in different pH conditions. We evaluated the cytotoxicity of D-ZIF on renal cell carcinoma (RCC786-O), glioma cells (U251), TAX-resistant human lung adenocarcinoma (A549-TAX) cells by CCK8 in vitro. We explored the possible antitumor mechanism of D-ZIF by Western blot. We evaluated the biocompatibility and hemolysis of D-ZIF and explored the in vivo antitumor efficiency in mice model by TUNEL testing and blood biomarker evaluations. D-ZIF showed rhombic dodecahedral morphology with size of 129±7.2 nm and possessed a noticeable DHA encapsulation efficiency (72.9%). After 48 hours, D-ZIF released a cumulative 70.0% of the loaded DHA at pH 6.5, and only 42.1% at pH 7.4. The pH-triggered programmed release behavior of D-ZIF could enhance anticancer effect of DHA while minimizing side effects under normal physiological conditions. Compared with the free DHA group with 31.75% of A549-TAX cell apoptosis, the percentage of apoptotic cells was approximately 76.67% in the D-ZIF group. D-ZIF inhibited tumor growth by inducing tumor cell apoptosis through the mechanism of ROS production and regulation of Nrf2/HO-1 and P38 MAPK signaling pathways. D-ZIF showed potent effects in treating tumors with high safety in vivo. This pH-responsive release mechanism enhanced the targeting efficiency of DHA towards tumor cells, thereby increasing drug concentration in tumor sites with negligible side effects. Herein, D-ZIF holds great promise for curing cancers with minimal adverse effects.

Synthesis of bimetallic Mn@ZIF–8 nanostructure for the adsorption removal of methyl orange dye from water

In this research, manganese-based Mn@ZIF-8 nanocomposite was prepared using solvothermal strategy. The resultant Mn@ZIF-8 nanostructure was assessed for the adsorption of methyl orange (MO) dye from water. The pristine ZIF-8 and Mn@ZIF-8 nanocomposite have demonstrated a rhombic dodecahedral morphology having a reasonable microporous structure. Besides, they have also displayed an outstanding specific surface area and porosity. The impact of contact time, concentration and variation in pH were analyzed in detail for the investigation of adsorption capacity. From the interpretation of the adsorption isotherms, it has been discovered that adsorption of MO over Mn@ZIF-8 follows the monolayer mechanism (Langmuir isotherm). Remarkable maximum adsorption capacity (qmax, 406 mg.g−1) has been recorded for the Mn@ZIF-8 which is sufficiently high as compared to pristine ZIF-8. The kinetic study explored that experimental data best fitted to the pseudo second order kinetics with relatively high R2 values (0.997) of Mn@ZIF-8. Thermodynamic study reconnoitered the adsorption process is spontaneous in nature. The synthesized Mn@ZIF-8 material also displays exceptional reusability capability of up to 92 % at 4th cycle compared to 1st cycle. Overall, the Mn@ZIF-8 could be a good contestant for the treatment of MO containing wastewater of industries.

Biologically inspired Co-MOF as catalase mimics with an unexpected ROS production ability for the efficient removal of organic dyes

Developing an efficient advanced oxidation technology is of great significance for water treatment and environmental protection. Here, inspired by the structure and feature of coenzyme B12 in natural enzymes (cleavage of Co-C bond triggers the generation of radical), a Co based metal-organic framework (Co-MOF) with catalase-mimicking activity was synthesized and applied in the degradation of organic dyes. Firstly, Co-MOF nanozyme was fabricated via the coordination self-assembly strategy at room temperature. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive scanning (EDS), powder X-ray diffraction (PXRD), and Fourier transform infrared spectroscopy (FTIR) were used to characterize the morphology and structure. The results showed that the obtained Co-MOF nanozyme was rhombic dodecahedral morphology with a size of ∼ 500 nm and excellent crystallinity. The enzymatic experiments proved that such nanozyme possessed a single catalase-like activity. Further research results demonstrated that Co-MOF-based degradation process of acid fuchsin (AF) or crystal violet (CV) had excellent pH adaptability (pH > 5.0). Unexpectedly, an ultra-high catalytic degradation rate (211.35 min−1 g−1 L) was successfully achieved in the catalytic degradation of AF, and it was approximately 5∼200 times of the previous optimal nanozyme or catalysts. In complex matrices and real wastewater, this catalytic process could still maintain degradation efficiency above 90% or even higher within 5 minutes, proving its excellent stability and adaptability. The results of radical and electron quenching experiments, electron paramagnetic resonance (EPR), and electrochemical analysis demonstrated that the excellent catalytic degradation performance was attributed to the generation of reactive oxygen species (ROS) (∙O2 was the main contributor) and the existence of electron transfer. In summary, this new catalytic property endows Co-MOF nanozyme with considerable potential for dye degradation, extending the application scope of catalase mimics.

Manganese Dioxide Nanoplatform with a Hollow Rhombic Dodecahedron Morphology for Drug Delivery.

Manganese dioxide (MnO2) is considered as a promising drug carrier material suitable for the tumor microenvironment while lacking conducive structures for drug loading. Herein, we construct a MnO2 nanoplatform with a hollow rhombic dodecahedral morphology for drug delivery. In this work, we obtained zeolitic imidazolate framework nanoparticles (ZIF-90 NPs) via a coordination reaction. Furthermore, the drug-loading nanoparticles (ZIF-90/DOX NPs) were obtained by Schiff's base reaction and then selected as a sacrificial template to obtain the hollow nanoplatforms (ZIF-90@MnO2 NPs). Moreover, the photothermal effect and multiresponsive drug release behaviors were revealed by loading the photothermal agent IR-820 and the anticancer drug doxorubicin hydrochloride (DOX). Our study demonstrates that the ZIF-90@MnO2 NPs loaded with photosensitizers exhibited excellent photothermal conversion performance. Benefiting from the hollow structure and redox activity, remarkable drug loading and release performances of ZIF-90@MnO2 NPs were achieved. It is shown that ZIF-90@MnO2 NPs achieved a satisfactory drug-loading efficiency (up to ca. 69.7%) for DOX. More promisingly, the ZIF-90@MnO2 NPs exhibited significant glutathione (GSH)/pH-responsive drug release and degradation performances. Overall, this work highlights the potential of controlled drug release of nanocarriers and offers unique insights into the design of nanocarriers with hollow structures.

Adsorptive stripping voltammetric sensor based on Cd zeolitic imidazole framework-67 for electrochemical detection of sarin simulant

A selective and reliable modified glassy carbon sensor, based on a 1.0% Cd zeolitic imidazole framework-67 modified glassy carbon sensor (GCS2), has been developed for ultrasensitive detection of dimethyl methyl phosphonate (DMMP) in human biological fluid. The synthesis of porous nanoparticles of Cd zeolitic imidazole framework-67 (Cd ZIF-67) was carried out via the hydrothermal method. The resulting Cd ZIF-67 powder emerges with good crystallinity, a rhombic dodecahedral morphology with particle size in the range 300 ~ 500 nm, and a specific surface area of 1780 m2·g−1. Furthermore, the fabricated sensor exhibited superior performance in the detection of DMMP with two linearity ranges of 0.02–2.0 nM and 2.0–9.0 nM and a limit of detection (LOD) of 0.06 pM. The fabricated sensor exhibited good reliability, long-term stability, and repeatability, which are favourable attributes for electroanalytical detection. In addition, the fabricated sensor displayed superior performance without significant interference during the assay of DMMP in a biological fluid (human serum sample) within two linearity ranges of 0.1–1.0 nM and 1.0–6.0 nM and a LOD of 0.03 nM.Graphical

Asymmetric supercapacitor device fabrication of pristine Zeolitic Imidazolate Framework-67 with ultrahigh performance and cyclic stability

Employing a simple stirring and cost-effective approach, the pristine Zeolitic Imidazolate Framework-67 (ZIF-67) material is prepared and utilized as an electrode in three- and two-electrode (asymmetric device) configurations. The synthesized material exhibits well-defined rhombic dodecahedral morphology, noteworthy porosity, and a high specific surface area (1109.54 m2g−1). In the three-electrode configuration, the electrochemical study reveals a high specific capacitance (CS) of 377.8 Fg−1 and an outstanding cyclic stability (118.2 %) in a 6 M NaOH aqueous electrolyte. Furthermore, a device with a voltage window of 1.2 V was built employing a positive electrode (ZIF-67) and a negative electrode of activated carbon (AC). Interestingly, the ASSC demonstrated a maximum device-specific capacitance (CS) of 222.40 Fg−1, high energy density (ED) of 21.45 WhKg−1, and the highest power density (PD) of 3231.07 Wkg−1. Afterward, the ASSC device demonstrated remarkable cyclic stability (178.7 %) over 4000 constant galvanostatic charge/discharge (GCD) cycles. Different colors of LEDs (Light Emitting Diodes) and their series combinations are lightened using three devices (connected in series). As a result of the exceptional presentation of ZIF-67, it acts as a possible choice for energy storage devices.

A versatile polyphenol-coordinated eco-friendly hollow ZIF-based nanohybrid for precise fungicide delivery and highly efficient suppression of Botrytis cinerea

Considerable attention has been focused on the development of smart and environmentally friendly nano-pesticides that can respond to environmental stimuli, to enhance pesticide utilization while mitigating environmental risks. In this study, boscalid (Bos), a potent fungicide, was loaded into hollow zeolitic imidazolate framework-8 nanoparticles (HZNs) and coordinated with tannic acid (TA) to fabricate a pH-responsive nanohybrid platform (Bos@HZNs@TA). Results demonstrated that the HZNs@TA carriers possessed a distinct rhombic dodecahedral morphology and enhanced hydrophilic properties. The loading capacity of Bos in HZNs@TA was approximately 38.43%. Bos@HZNs@TA exhibited excellent adhesion to tomato leaves and washout resistance. Notably, the release amount of Bos from Bos@HZNs@TA at pH = 5.5 reached 84.6%, which was higher than that at neutral pH conditions for 72 h. The pH-responsive release characteristics of Bos@HZNs@TA was advantageous for its response to the acidic microenvironment created by Botrytis cinerea (B. cinerea). Additionally, Bos@HZNs@TA demonstrated exceptional effectiveness in controlling B. cinerea, surpassing the commercial Bos suspension concentrate. Importantly, Bos@HZNs@TA had no discernible adverse effects on the three non-target organisms, implying a good biocompatibility. This study provides a smart, eco-friendly, and sustainable approach to control B. cinerea effectively for plant protection.

Ultra-fine potassium hexacyanoferrate(II) nanoparticles modified ZIF-67 for adsorptive removal of radioactive strontium from nuclear wastewater

Development of a material with high adsorption capacity and selectivity for removal of strontium ion (Sr2+) from nuclear wastewater is a challenge. Herein, dodecahedral zeolitic imidazolate frameworks-67 (ZIF-67) was successfully modified by potassium hexacyanoferrate(Ⅱ) (K4Fe(CN)6) nanoparticles, and used as an effective adsorbent for Sr2+ removal from model wastewater. In construction of adsorbent, methanol was used as the medium for assembly of ultra-fine and uniform 25 nm of K4Fe(CN)6 nanoparticles on ZIF-67, well maintaining the original dodecahedral morphology and mesoporous structure of ZIF-67 crystal. N in 2-methylimidazole (2-MI) bonded with Co to generate ZIF-67, while the unsaturated Co in ZIF-67 bonded with N in K4Fe(CN)6 to form spherical nanoparticles. Specific surface area of ZIF-67 were regulated by K4Fe(CN)6 to an appropriate value of 607.464 m2·g−1 for Sr2+ adsorption. Adsorption efficiency of K4Fe(CN)6 modified ZIF-67 for Sr2+ was significantly enhanced to 90 % within 2 h at ambient conditions, due to the improvement in morphology, structure and chemical property of adsorbent. K4Fe(CN)6 modified ZIF-67 exhibited high adsorption selectivity 45 mg·g−1 for Sr2+ in the presence of competing metal ions such as K+, Na+, Mg2+ and Ca2+, and thus achieved 40 mg·g−1 of adsorption capacity for Sr2+ in actual tap water. Adsorption kinetics and isotherms were well fitted with the second-order kinetics and the Langmuir model, respectively, suggesting a chemisorption process. Mechanism studies showed that the surface of ZIF-67 was uniformly covered by ultra-fine nanoparticles, on the outer layer of which K+ ions were distributed as the adsorption sites for ion exchange with Sr2+.

High-performance multifunctional gelatin-based films engineered with metal-organic frameworks for active food packaging applications

Eco-friendly multifunctional composite films were designed using gelatin (Gel) and metal-organic frameworks ZIF-8 (Zn-MOFs) to meet the demand for active packaging that ensures food shelf life. The synthesized Zn-MOF nanostructures exhibited a dodecahedral morphology with antioxidant activity, UV absorption, and antibacterial properties. The added Zn-MOFs particles showed good dispersion in the gelatin matrix, creating a dense composite film structure. The incorporation of Zn-MOFs enhanced the physical characteristics of the developed films, such as water resistance, thermal stability, tensile strength, and UV shielding properties. The addition of 1 and 3 wt% Zn-MOFs in the gelatin matrix resulted in 84.4% and 100% antioxidant activity, respectively. MOFs-loaded gelatin film demonstrated excellent antibacterial function against Gram-positive (S. aureus &L. monocytogenes) and Gram-negative (S. enterica &E. coli) bacteria. The potential application of the engineered composite films in the food packaging field is studied by fresh cherry tomato packing, and physicochemical and microbiological properties of packed samples were monitored for a storage period of 16 days at 10 °C. The Gel/Zn-MOF3% film retarded the texture deterioration of packed tomatoes and displayed a microorganism growth prevention effect, expecting its practical potential for use in multifunctional active packaging prospects.

Enhanced Heterogeneous Activation of Peroxymonosulfate by Nitrogen–Sulfur Co-Doped Mofs-Derived Carbon

It is important to further enhance the performance of green and efficient non-homogeneous catalysts for advanced oxidation process of Peroxymonosulfate (PMS-AOP) for green treatment of industrial wastewater. In this paper, nitrogen–sulfur co-doped MOFs-derived carbon material (CoSN@C) was prepared by one-pot synthesis followed by carbonization, and its morphological structure was characterized by XRD and SEM. After pyrolysis, the CoSN@C still maintained the dodecahedral morphology and structure of ZIF-67. The synergistic effects of S and N significantly elevated the activation of PMS. The results show that the CoSN@C + PMS system can effectively activate PMS to degrade Rhodamine B (RhB), with a rate constant (1.85 min−1) four times higher than that of the CoN@C + PMS system (0.44 min−1). The optimal catalytic process parameters of material dosage, PMS concentration, temperature, pH, and other parameters were also investigated for the activation of PMS to remove Rhodamine B. The cyclic experiment shows that the CoSN@C has excellent recyclability and the degradation rate of RhB still reached 88.9% after four cycles. Radical capture experiments and EPR tests showed that the CoSN@C + PMS system generated a large amount of SO4·− and ·OH radicals adsorbed on the catalyst surface and a certain amount of singlet oxygen, and the free radical pathway and non-radical pathway worked together to degrade RhB efficiently and rapidly. While non-radical pathway with singlet oxygen as main reactive oxygen species played a key role in the CoN@C + PMS system. This work provides a new idea for the rational design of non-homogeneous catalysts for PMS-AOP system.

Efficient direct electrocatalysis of nano-dodecahedron for the highly sensitive and selective detection of rutin

Herein, hollow and porous nano-dodecahedron embedded with cobalt oxide nanoparticles (HPND-CN) was prepared for the detection of rutin (Rut). HPND-CN was synthesized by the pyrolysis of zeolitic imidazolate frameworks (ZIFs). HPND-CN displayed a uniform rhombic dodecahedral morphology. For the main architecture, the original framework was carbonized after pyrolysis leading to a porous graphitized polyhedron with nitrogen doping. Notably, in the polyhedron, spherical cobalt oxide nanoparticles with more CoO and less Co2O3 were evenly implanted. With embedded oxide nanoparticles, active doping species, polyhedral morphology, and porous graphitized structure, HPND-CN displayed a strong electrocatalysis towards the redox of Rut. A pair of well-defined symmetric peaks for Rut redox was clearly observed. Based on the electrocatalysis of HPND-CN, an efficient Rut sensor was developed with a low detection limit of 1.9 nM and broad detection range from 7.0 nM to 1.0 μM. HPND-CN prepared sensor also exhibited a superb selectivity showing no interference from common inorganic ions, carbohydrates, and amino acids. Besides, excellent repeatability, reproducibility and reliability were observed. Moreover, HPND-CN sensor was successfully applied to the measurement of Rut in health-care tablets with convinced results, indicating a substantial electrochemical sensing platform for the electrocatalysis and detection of macromolecules.

Understanding the agglomerate crystallisation of hexamine through X-ray microscopy and crystallographic modelling

The detailed molecular-scale mechanism of the growth of organic crystals underpins a diversity of phenomena, such as the isolation and purification of high-quality materials for the pharmaceutical and fine chemical sectors. Recent advances in X-ray Microscopy (XRM) and complementary diffraction contrast tomography (DCT) have enabled the detailed characterisation of the micro-structure of hexamine agglomerates. Detailed XRM analysis of the growth history and micro-structure of such agglomerates reveals a highly orientated epitaxial inter-relationship between their constituent micro-crystallites. This is found to be consistent with a secondary nucleation growth mechanism associated with re-growth at the 3-fold corner sites within the crystals’ dominant {110} dodecahedral morphology. The agglomeration appears to heal upon further growth as the aligned agglomerated micro-crystals connect and fuse together but, in doing so, pockets of inter-crystallite mother liquor become trapped forming a symmetric pattern of solvent inclusions. The mechanistic origin of this phenomenon is rationalised with respect to historical data together with an analysis of the solid-state chemistry of the compound through the development of a ‘snow flake’ model. The latter draws upon hexamine’s propensity for edge growth instabilities with increasing crystal size as well as its tendency for unstable growth at the facet corners along the 〈111〉 directions, a situation compounded by the lack of growth-promoting dislocations at the centers of the {110} habit surfaces. The agglomerative mechanism presented here could apply to other high symmetry crystal systems, particularly those whose crystal structures involve centred Bravais lattices and where the dominant inter-molecular interactions are angled towards the facet edges.

A General Concurrent Template Strategy for Ordered Mesoporous Intermetallic Nanoparticles with Controllable Catalytic Performance

AbstractWe report a general concurrent template strategy for precise synthesis of mesoporous Pt‐/Pd‐based intermetallic nanoparticles with desired morphology and ordered mesostructure. The concurrent template not only supplies a mesoporous metal seed for re‐crystallization growth of atomically ordered intermetallic phases with unique atomic stoichiometry but also provides a nanoconfinement environment for nanocasting synthesis of mesoporous nanoparticles with ordered mesostructure and rhombic dodecahedral morphology under elevated temperature. Using the selective hydrogenation of 3‐nitrophenylacetylene as a proof‐of‐concept catalytic reaction, mesoporous intermetallic PtSn nanoparticles exhibited remarkably controllable intermetallic phase‐dependent catalytic selectivity and excellent catalytic stability. This work provides a very powerful strategy for precise preparation of ordered mesoporous intermetallic nanocrystals for application in selective catalysis and fuel cell electrocatalysis.

Hierarchical MCo2O4@Ni(OH)2 (M = Zn or Mn) core@shell architectures as electrode materials for asymmetric solid-state supercapacitors

In this study, the self-assembled Ni(OH)2-nanosheet-adorned hierarchical MCo2O4@Ni(OH)2 (M = Zn or Mn) core@shell heterostructures are prepared by a three-step process, via tuning the core-compositions, as advanced electrodes for supercapacitors (SCs). The tuning of the core composition makes a significant impact on the physicochemical properties, morphology, and electrochemical performance. Among the MCo2O4@Ni(OH)2 materials, the nanopine forest-like ZnCo2O4@Ni(OH)2 optimal architecture exhibits superior supercapacitive performance (areal/specific capacity, 1.34 mA h cm−2/432.6 mA h g−1 at 3 mA cm−2 current density and a ∼90% cycling stability upto 5000 cycles). Meanwhile, 3D porous nitrogen-doped carbon (PNC) with perfect rhombic dodecahedral morphology is used as negative electrode material with high surface area (1600 m2 g−1), excellent capacity (49.2 mA h g−1 at 2 mA cm−2) and rate performance (∼55% at 50 mA cm−2). The solid-state asymmetric device comprising ZnCo2O4@Ni(OH)2 (positive electrode) and hierarchical PNC (negative electrode) affords a high cell capacity of 97.8 mA hg−1 at 4 mA cm−2, with 86% cycle stability after 10,000 cycles. Moreover, the device exhibits 78.2 W h kg–1 of energy density at a power density of 451 W kg−1 and 40.4 W h kg−1 of energy density at 4691.0 W kg−1 of power density. This study provides insight into electro-active material design and construction of heteronanostructures for high-performance SCs.