Interconnected Macropores Research Articles

Improvement of pea protein gelation at reduced temperature by atmospheric cold plasma and the gelling mechanism study

Pea protein as an alternative of soy protein has attracted growing interest in food industries. However, high temperature (> 95 °C) is required to enable heat-induced gelation and the formed gels are relatively weak. This research aimed to study the efficacy of atmospheric cold plasma (ACP) as a novel non-thermal technique to improve the gelling properties of pea protein. While native pea protein concentrate (PPC) (12 wt%) could not form gel under 90 °C, ACP-treated PPC showed good gelling properties when heated at 70–90 °C. The gels exhibited homogeneous three-dimensional network structure with interconnected macropores, and those prepared at 80 and 90 °C possessed good mechanical strength and viscoelasticity, as well as high water holding capacity. The gelling mechanism was studied by monitoring pea protein structural changes during ACP treatment and gel formation process via a transmission electron microscope, a Fourier transform infrared spectrometer, and a rheometer. These results revealed that ACP treatment contributed to the formation of protein fibrillar aggregates, and significantly reduced the PPC denaturation temperature, leading to protein unfolding at reduced temperature of 80–90 °C. ACP treatment also increased the protein surface hydrophobicity and exposed free sulfhydryl groups, which could facilitate the formation of hydrophobic interactions and disulfide bonds, leading to gels with improved mechanical properties. Moreover, hydrogen bonding could play an important role to stabilize the gel network during the gelling process. Owing to the short exposure time and energy efficiency, ACP is a promising technology to enable wide applications to pea protein as a gelling ingredient of plant protein-based food products, such as meat analogues and egg alternatives.

(Invited) Defective Hierarchical Porous Copper-Based Metal-Organic Frameworks Synthesised Via Facile Acid Etching Strategy

Introducing hierarchical pore structure to microporous materials such as metal-organic frameworks (MOFs) can be beneficial for reactions where the rate of reaction is limited by low rates of diffusion or high pressure drop. This advantageous pore structure can be obtained by defect formation, mostly via post-synthetic acid etching, which has been studied extensively on water-stable MOFs. Here we show that a water-unstable HKUST-1 MOF can also be modified in a corresponding manner by using phosphoric acid as a size-selective etching agent and a mixture of dimethyl sulfoxide and methanol as a dilute solvent. Interestingly, we demonstrate that the etching process which is time- and acidity- dependent, can result in formation of defective HKUST-1 with extra interconnected hexagonal macropores without compromising on the bulk crystallinity. These findings suggest an intelligent scalable synthetic method for formation of hierarchical porosity in MOFs that are prone to hydrolysis, for improved molecular accessibility and diffusion for catalysis. Figure 1

Fabrication of Macroporous Nafion Membrane from Silica Crystal for Ionic Polymer-Metal Composite Actuator

Nafion membrane with macropores is synthesized from silica crystal and composited with Pt nanoparticles to fabricate macroporous ionic polymer-metal composite (M-IPMC) actuator. M-IPMC shows highly dispersed small Pt nanoparticles on the porous walls of Nafion membrane. After the electromechanical performance test, M-IPMC actuator demonstrates a maximum displacement output of 19.8 mm and a maximum blocking force of 8.1 mN, far better than that of IPMC actuator without macroporous structure (9.6 mm and 2.8 mN) at low voltages (5.8–7.0 V). The good electromechanical performance can be attributed to interconnected macropores that can improve the charge transport during the actuation process and can allow the Pt nanoparticles to firmly adsorb, leading to a good electromechanical property.

Rational design of silicas with meso-macroporosity as supports for high-performance solid amine CO2 adsorbents

Silica-supported amine adsorbents are extensively studied for CO2 capture. However, rational design of silica materials with specific pore structures as amine supports for large CO2 adsorption capacity, fast adsorption-desorption kinetics, easy regeneration, and good cyclic performance, still remains a challenge. Herein, we synthesize a series of ordered silicas with either bimodal or trimodal meso-macro porosities through a single- or double-templating route as supports for polyethylenimines (PEI) to make solid amine CO2 adsorbents. Bimodal silicas with textural mesopores and interconnected macropores are ideal supports at medium amine loading, illustrated by significantly high amine efficiencies, e.g., 50BPEI (800)/PS-80-00 achieves a CO2 uptake of 350 mg g−1 PEI at 75 °C, 1 bar, which is the one of the highest values among PEI/silica composites reported so far; however, further increase of amine loading leads to severe amine efficiency fading. In comparison, trimodal silicas with internal mesopores, textural mesopores, and interconnected macropores show outstanding performance at high amine loading, e.g., 70BPEI (800)/PS-80-187 exhibits a CO2 adsorption capacity of 215 mg g−1 adsorbent at 75 °C, 1 bar, which is one of the highest values among reported PEI/silica composites. Moreover, we also study the correlations of the CO2 adsorption capacity and kinetics, regeneration of adsorbent, and cyclic CO2 adsorption-desorption performance with the PEI type, PEI loading amount, and operation temperatures. This work brings insight into factors affecting the CO2 capture performance for amine-impregnated silica composites, providing an important guidance to design high-performance solid amine CO2 adsorbents in the near future.

Highly effective adsorption of copper ions by poly(vinyl imidazole) cryogels

Recently, 3D cryogels with the interconnected macropore structure have gained great attention owing to their immense application potential in wastewater cleanup. Here, we fabricated a pure poly(vinyl imidazole) cryogel through improved cryogelation method, adding the pre-freezing–thawing step, which reduced the temperature difference between the different positions of the precursor solution during reaction. Compression experiments showed that the prepared 3D cryogel featured a robust underwater elastic performance. The adsorption capacity of Cu(II), Ni(II), Zn(II), Co(II), Pb(II), and Cd(II) ions from aqueous solutions by the poly(vinyl imidazole) cryogel was explored. The results showed the specific adsorption of Cu(II), in which the adsorption capacity and removal efficiency reached 148 mg/g and 99.99%, respectively. The adsorption capacity was 58 times higher than that of the reported poly(vinyl imidazole) cryogel which was prepared using hydroxyethyl methacrylate as the comonomer frameworks. In the reusability studies, the cryogel exhibited accumulating Cu(II) ions performance and excellent regeneration capability, making it a promising adsorbent for Cu(II) removal.

Efficient regeneration of rat calvarial defect with gelatin-hydroxyapatite composite cryogel

To induce bone regeneration efficiently, a properly designed organic-inorganic composite scaffold is necessary and important. Gelatin-hydroxyapatite (HA) composite is a suitable choice for the purpose because it can resemble the chemical composition of natural bone tissue. The gelatin-HA composite can be implanted into bone defects as a hydrogel or cryogel, however, it is interesting to know the effect of their different morphology on inducing osteogenesis in vivo. Herein, HA nanowire (HANW) reinforced photocrosslinkable methacrylated gelatin (GelMA) cryogel and hydrogel are prepared and comparatively investigated by being implanted into rat calvarial defects. The cryogel acts as a kind of sponge with interconnected macropores, allowing cell infiltration, as well as, displaying rapid shape recovery and excellent mechanical stability under cyclic compression loading. Conversely, the hydrogel is rigid and easily crushed during the first compression test, showing no shape recovery ability, instead inhibiting cell migration and spreading. Accordingly, the GelMA/HANW composite cryogel is able to promote osteogenesis significantly more in comparison with the corresponding hydrogel at six and 12 weeks post-implantation, as revealed by comprehensive evaluations using radiographic examination, histochemical and immunohistochemical staining methods. Neo-bone tissues have grown into the macroporous cryogel six and 12 weeks after the implantation, while the dense hydrogel prevents the tissue ingrowth, causing the newly formed sparse bone tissue to only elongate into the gaps between cracked hydrogel blocks. In summary, organic-inorganic macroporous cryogels demonstrate superiority for in vivo applications to induce bone regeneration.

Hierarchically Structured DNA‐Based Hydrogels Exhibiting Enhanced Enzyme‐Responsive and Mechanical Properties

AbstractProgrammable stimuli‐responsive materials have great potential in biosensing and biomedical applications. However, the slow response of DNA hydrogels to biological targets, especially bio‐macromolecules, i.e., proteins, due to the slow mass transfer within hydrogel matrices, as well as poor mechanical strength, severely hinders their extensive applications. Herein, the construction of hierarchically structured DNA hydrogels exhibiting significantly enhanced responsive and mechanical properties via a facile cryostructuration process is demonstrated. During the cryostructuration, interconnected macropores that can function as the channels for the migration of bio‐macromolecular substances, i.e., enzymes, are formed with the generated ice crystals as templates; meanwhile, densely crosslinked networks between the macropores are formed by the concentrated monomers localized in the unfrozen zones of the gelation system, leading to higher strength of the gel matrices. By programming the sequences of the DNA crosslinkers, two model hydrogels composed of enzyme‐responsive DNA structures and catalytic DNA crosslinking structures that can collaborate with enzymes to form biocatalytic cascades are constructed, and, in both systems, the hierarchically structured DNA hydrogels exhibit significantly enhanced responsive properties and mechanical strengths compared with typical DNA hydrogels. Moreover, the introduction of thermosensitive polymers can further endow the system with thermally switchable responsive properties.

In vitro Apatite Mineralization, Degradability, Cytocompatibility and in vivo New Bone Formation and Vascularization of Bioactive Scaffold of Polybutylene Succinate/Magnesium Phosphate/Wheat Protein Ternary Composite.

PurposeA bioactive and degradable scaffold of ternary composite with good biocompatibility and osteogenesis was developed for bone tissue repair.Materials and MethodsPolybutylene succinate (PS:50 wt%), magnesium phosphate (MP:40 wt%) and wheat protein (WP:10 wt%) composite (PMWC) scaffold was fabricated, and the biological performances of PMWC were evaluated both in vitro and vivo in this study.ResultsPMWC scaffold possessed not only interconnected macropores (400 μm to 600 μm) but also micropores (10 μm ~20 μm) on the walls of macropores. Incorporation of MP into composite improved the apatite mineralization (bioactivity) of PMWC scaffold in simulated body fluid (SBF), and addition of WP into composite further enhanced the degradability of PMWC in PBS compared with the scaffold of PS (50 wt%)/MP (50 wt%) composite (PMC) and PS alone. In addition, the PMWC scaffold containing MP and WP significantly promoted the proliferation and differentiation of mouse pre-osteoblastic cell line (MC3T3-E1) cells. Moreover, the images from synchrotron radiation microcomputed tomography (SRmCT) and histological sections of the in vivo implantation suggested that the PMWC scaffold containing MP and WP prominently improved the new bone formation and ingrowth compared with PMC and PS. Furthermore, the immunohistochemical analysis further confirmed that the PMWC scaffold obviously promoted osteogenesis and vascularization in vivo compared with PMC and PS.ConclusionThis study demonstrated that the biocompatible PMWC scaffold with improved bioactivity and degradability significantly promoted the osteogenesis and vascularization in vivo, which would have a great potential to be applied for bone tissue repair.

Production of Biodegradable Palm Oil-Based Polyurethane as Potential Biomaterial for Biomedical Applications.

Being biodegradable and biocompatible are crucial characteristics for biomaterial used for medical and biomedical applications. Vegetable oil-based polyols are known to contribute both the biodegradability and biocompatibility of polyurethanes; however, petrochemical-based polyols were often incorporated to improve the thermal and mechanical properties of polyurethane. In this work, palm oil-based polyester polyol (PPP) derived from epoxidized palm olein and glutaric acid was reacted with isophorone diisocyanate to produce an aliphatic polyurethane, without the incorporation of any commercial petrochemical-based polyol. The effects of water content and isocyanate index were investigated. The polyurethanes produced consisted of > 90% porosity with interconnected micropores and macropores (37–1700 µm) and PU 1.0 possessed tensile strength and compression stress of 111 kPa and 64 kPa. The polyurethanes with comparable thermal stability, yet susceptible to enzymatic degradation with 7–59% of mass loss after 4 weeks of treatment. The polyurethanes demonstrated superior water uptake (up to 450%) and did not induce significant changes in pH of the medium. The chemical changes of the polyurethanes after enzymatic degradation were evaluated by FTIR and TGA analyses. The polyurethanes showed cell viability of 53.43% and 80.37% after 1 and 10 day(s) of cytotoxicity test; and cell adhesion and proliferation in cell adhesion test. The polyurethanes produced demonstrated its potential as biomaterial for soft tissue engineering applications.

Gamma-FeOOH based hierarchically porous zeolite monoliths for As(V) removal: Characterisation, adsorption and response surface methodology

γ-FeOOH based hierarchical zeolite LTA monoliths as sorbents for As(V) removal were synthesized by modifying hierarchical zeolite LTA monoliths with HCl and FeCl3 solutions. The obtained γ-FeOOH based monoliths (abbreviated as Fe-HZ) maintain the interconnected macropores network structure, which offers a practical solution to the diffusion limitations associated with traditional agglomerated zeolites. Moreover, the self-supported sorbents can be easily recycled after treatment. The derived γ-FeOOH based monolith exhibits higher BET surface area while slightly decreased thermal stability compared with those unmodified sample (labeled as HZ). The sorption performance of HZ and Fe-HZ are evaluated, taking the initial/equilibrium pH, adsorption time and initial concentration into account. Fe-HZ shows an optimal adsorption over the pH range 2–7, and the uptake capacity is 5.11 mg/g at pH of 6 with the equilibrium time of 240 min. Whereas only 0.67 mg/g can be attained for HZ. The dynamic data follows pseudo-second-order model, demonstrating As(V) species chemisorbed on Fe-HZ, and the chemisorption is ascribed to ligand exchange reactions between As(V) species and hydroxyl functional groups. Freundlich and Langmuir isotherms are both acceptable for the equilibrium data of arsenic adsorption on Fe-HZ. In addition, response surface methodology is applied for modeling and optimization monoliths preparation parameters. Results show that the importance of variable factors influencing arsenic adsorption follows the sequence: FeCl3 concentration > PMMA/MK mass ratio > FeCl3 modification time > HCl modification time.

Oxidative Desulfurization of DBT with H2O2 over 3DOM H3PW12O40/Al2O3 Catalyst

A series of heteropoly acid (HPA) based Al2O3 catalysts with three-dimensional ordered (3DOM) structure were synthesized by colloidal crystal template method. Interconnected macropores (250 nm) could be clearly observed by scanning electron microscope (SEM) and transmission electron microscope (TEM). Mesopores could be detected by N2 adsorption-desorption isotherms which further confirmed the 3DOM structural characteristics of catalyst. Moreover, Keggin-type HPW was highly dispersed in the Al2O3 framework, which suggested by powder X-ray diffraction (XRD) and Fourier transform infrared spectra (FT-IR) results. The oxidation desulfurization (ODS) performance of 3DOM H3PW12O40/Al2O3 of refractory sulphur compounds was evaluated in the presence of hydrogen peroxide. It oxidized 98.5% of dibenzothiophene (DBT) into corresponding sulfone within 3 h, which exhibited superior ODS performance than corresponding mesoporous and microporous H3PW12O40/Al2O3 catalyst. The enhancement of ODS efficiency is related to the improvement of mass transfer of DBT in the pore channel resulting from the interconnected 3DOM structure. Furthermore, the as-prepared catalyst still demonstrates outstanding cycle performance after 6 runs, which could be easily recovered from the model fuel.

Deep-Breathing Honeycomb-like Co-Nx-C Nanopolyhedron Bifunctional Oxygen Electrocatalysts for Rechargeable Zn-Air Batteries.

SummaryMetal organic framework (MOF) derivatives have been extensively used as bifunctional oxygen electrocatalysts. However, the utilization of active sites is still not satisfactory owing to the sluggish mass transport within their narrow pore channels. Herein, interconnected macroporous channels were constructed inside MOFs-derived Co-Nx-C electrocatalyst to unblock the mass transfer barrier. The as-synthesized electrocatalyst exhibits a honeycomb-like morphology with highly exposed Co-Nx-C active sites on carbon frame. Owing to the interconnected ordered macropores throughout the electrocatalyst, these active sites can smoothly “exhale/inhale” reactants and products, enhancing the accessibility of active sites and the reaction kinetics. As a result, the honeycomb-like Co-Nx-C displayed a potential difference of 0.773 V between the oxygen evolution reaction potential at 10 mA cm−2 and the oxygen reduction reaction half-wave potential, much lower than that of bulk-Co-Nx-C (0.842 V). The rational modification on porosity makes such honeycomb-like MOF derivative an excellent bifunctional oxygen electrocatalyst in rechargeable Zn-air batteries.

Investigation of bone reconstruction using an attenuated immunogenicity xenogenic composite scaffold fabricated by 3D printing

Bone is known to have a natural function to heal itself. However, if the bone damage is beyond a critical degree, intervention such as bone grafting may be imperative. In this work, the fabrication of a novel bone scaffold composed of natural bone components and polycaprolactone (PCL) using 3D printing is put forward. α1, 3-galactosyltransferase deficient pigs were used as the donor source of a xenograft. Decellularized porcine bone (DCB) with attenuated immunogenicity was used as the natural component of the scaffold with the aim to promote bone regeneration. The 3D printed DCB-PCL scaffolds combined essential advantages such as uniformity of the interconnected macropores and high porosity and enhanced compressive strength. The biological properties of the DCB-PCL scaffolds were evaluated by studying cell adhesion, viability, alkaline phosphatase activity and osteogenic gene expression of human bone marrow-derived mesenchymal stem cells. The in vitro results demonstrated that the DCB-PCL scaffolds exhibit an enhanced performance in promoting bone differentiation, which is correlated to the DCB content. Furthermore, critical-sized cranial rat defects were used to assess the effect of DCB-PCL scaffolds on bone regeneration in vivo. The results confirm that in comparison with PCL scaffolds, the DCB-PCL scaffolds can significantly improve new bone formation in cranial defects. Thus, the proposed 3D printed DCB-PCL scaffolds emerge as a promising regeneration alternative in the clinical treatment of large bone defects.

Few-layer MoS2 embedded in N-doped carbon fibers with interconnected macropores for ultrafast sodium storage

Sodium-ion battery has been considered as one of the most promising next-generation rechargeable energy storage devices. However, it remains a great challenge to exploit suitable electrode materials for sodium storage owing to relatively large radius of Na+. In this study, a novel 1D fiber-like electrode material integrating few-layer MoS2, ultrathin carbon continuous framework, doped N atoms and well-defined 3D connected macropores is developed by electrospinning (denoted as MoS2/NCF-MP). When used as anode in sodium ion battery, its unique structural hierarchy is able to maximumly diminish the solid-state diffusion length, lower electrochemical resistance, accelerate Na+ transfer from bulk to electrode, and relieve the volume variation during sodiation/desodiation process, thus displays highly reversible capacity, long-term durability, along with ultrafast sodium storage capability. The stable reversible capacity of MoS2/NCF-MP reaches 480 mAh g−1 at 0.1 A g−1 after 100 cycles, and undergoes a long cycling life of 300 cycles at 1 A g−1, no visible capacity degradation is observed. More importantly, even under a very high current density of 30 A g−1, the MoS2/NCF-MP can deliver a commendable capacity of 217 mAh g−1, which means the charge/discharge step can be completed within a very short time of 26 s.

Hierarchical bead chain ZnFe2O4-PEDOT composites with enhanced Li-ion storage properties as anode materials for lithium-ion batteries

In this study, we synthesized hierarchical bead chain ZnFe2O4-PEDOT composites with network of macroporous channels. For the first time, a ZnFe2(C2O4)3 precursor was prepared by co-precipitation using steel waste pickling liquor as a raw material, which was then sintered in air at 800 °C to yield monolithic ZnFe2O4. PEDOT was coated on the surface of ZnFe2O4 via in-situ polymerization of 3,4-ethylenedioxythiophene (EDOT). Electrochemical measurements showed that the 15 wt% PEDOT coated ZnFe2O4 composites (ZFPE-15) delivered a discharge capacity of 1510.5 mAh g−1 at 100 mA g−1 after 200 cycles, which was much larger than that of pure ZnFe2O4 (1055.9 mAh g−1), 10 wt% PEDOT coated ZnFe2O4 composites (ZFPE-10, 1264.2 mAh g−1), and 20 wt% coated ZnFe2O4 composites (ZFPE-20, 900.1 mAh g−1). Additionally, the ZFPE-15 composite exhibited a reversible capacity of 1004.7 mAh g−1, even at a large current density of 1 A g−1 after 200 cycles. These more desirable electrochemical properties can be attributed to the interconnected macroporous channels in the hierarchical bead chain skeleton, which can buffer volume expansion during circulation and inhibit particle agglomeration. Furthermore, the PEDOT nanoparticle coating produces a composite with greater mechanical strength and higher electrical conductivity, which provides higher electron transfer during the charge/discharge processes.

Novel Extrusion-Microdrilling Approach to Fabricate Calcium Phosphate-Based Bioceramic Scaffolds Enabling Fast Bone Regeneration.

This study proposes a novel approach, termed extrusion-microdrilling, to fabricate three-dimensional (3D) interconnected bioceramic scaffolds with channel-like macropores for bone regeneration. The extrusion-microdrilling method is characterized by ease of use, high efficiency, structural flexibility, and precision. The 3D interconnected β-tricalcium phosphate bioceramic (EM-TCP) scaffolds prepared by this method showed channel-like square macropores (∼650 μm) by extrusion and channel-like round macropores (∼570 μm) by microdrilling as well as copious micropores. By incorporating a strontium-containing phosphate-based glass (SrPG), the obtained calcium phosphate-based bioceramic (EM-TCP/SrPG) scaffolds had noticeably higher compressive strength, lower porosity, and smaller macropore size, tremendously enhanced in vitro proliferation and osteogenic differentiation of mouse bone marrow stromal cells, and suppressed in vitro osteoclastic activities of RAW264.7 cells, as compared with the EM-TCP scaffolds. In vivo assessment results indicated that at postoperative week 6, new vessels and a large percentage of new bone tissues (24-25%) were formed throughout the interconnected macropores of EM-TCP and EM-TCP/SrPG, which were implanted in the femoral defects of rabbits; the bone formation of the EM-TCP group was comparable to that of the EM-TCP/SrPG group. At 12 weeks postimplantation, the bone formation percentage of EM-TCP was slightly reduced, while that of EM-TCP/SrPG with a slower degradation rate was pronouncedly increased. This work provides a new strategy to fabricate interconnected bioceramic scaffolds allowing for fast bone regeneration, and the EM-TCP/SrPG scaffolds are promising for efficiently repairing bone defects.

Preparation and graft modification of hierarchically porous ferriferrous oxide for heavy metal ions adsorption

Hierarchically porous ferriferrous oxide (Fe3O4) was facilely synthesized via a sol-gel process accompanied by phase separation, and further graft modified by dopamine (DA) and polyamido-amine (PAMAM) to prepare macroporous Fe3O4@DA@PAMAM for heavy metal ions adsorption. Appropriate phase separation inducer (poly(acrylamide), PAA) and solvent allows the formation of iron oxide xerogels with interconnected macropores and cocontinuous skeletons. Two-step heat treatment at 200 °C for 30 min in air and then at 500 °C for 2 h in N2 atmosphere leads to the precipitation of crystalline phase, Fe3O4, with high magnetic properties, without any deterioration of the macrostructure. The macroporous Fe3O4@DA@PAMAM show a core-shell structure and high adsorption capacity for Cu(II), Pb(II), and Cd(II) ions, which are promisingly used for removal of heavy metal ions.

Monolithic macroporous hydrogels prepared from oil-in-water high internal phase emulsions for high-efficiency purification of Enterovirus 71

Monolithic macroporous hydrogels was prepared from oil-in-water high internal phase emulsions (HIPEs) and heparinized using polydopamine (PDA) and polyethyleneimine (PEI) as mediators, and then used as a support of affinity chromatography to purify Enterovirus 71 (EV71) from culture supernatant. Our innovative strategy was characterized by two remits. (1) Interconnected macropores (1–5 μm) and high porosity (76–93%) of hydrophilic hydrogels ensured an excellent permeability (6.95 × 10−13 m2); (2) PDA/PEI composite provided abundant amino groups to immobilize heparin on macroporous hydrogels and increased the amount of carboxyl group to 46.5 μmol per column. A selective recognition of EV71 was achieved by receptor-ligand interaction between heparin and EV71. The adsorption capacity for EV71 was 986.0 ng per column and the recovery for EV71 reached a maximum of 79.9%. It was verified that these high performances were ascribed to the high density of heparin immobilized via PDA and PEI as mediators. Our innovative strategy provided a useful paradigm as a preparation method for heparin-affinity chromatographic medium for virus purification.

A Zeolitic-Imidazole Frameworks-Derived Interconnected Macroporous Carbon Matrix for Efficient Oxygen Electrocatalysis in Rechargeable Zinc-Air Batteries.

Nanostructures derived from zeolitic-imidazole frameworks (ZIFs) gain much interest in bifunctional oxygen electrocatalysis. However, they are not satisfied well for long-life rechargeable zinc-air batteries due to the limited single particle morphology. Herein, the preparation of an interconnected macroporous carbon matrix with a well-defined 3D architecture by the pyrolysis of silica templated ZIF-67 assemblies is reported. The matrix catalyst assembled zinc-air battery exhibits a high power density of 221.1 mW cm-2 as well as excellent stability during 500 discharging/charging cycles, surpassing that of a commercial Pt/C assembled battery. The synergistic effect from the interconnected macroporous structure together with abundant cobalt-nitrogen-carbon active sites justify the excellent electrocatalytic activity and battery performance. Considering the advanced nanostructures and performance, the as-synthesized hybrid would be promising for rechargeable zinc-air batteries and other energy technologies. This work may also provide significant concept in the view of electrocatalysis design for long-life battery.

Sb-doped three-dimensional ZnFe2O4 macroporous spheres for N-butanol chemiresistive gas sensors

In this paper, the preparation process and gas sensing performance of Sb-doped three-dimensional spinel ferrite (3D ZnFe2O4) with well-assembled macroporous spherical structure have been investigated. Sb-doped 3D ZnFe2O4 macroporous spheres (MPs) were prepared through a one-step ultrasonic spray pyrolysis (USP) method by sacrificing self-assembly sulfonated polystyrene spheres (S-PSs). The interconnected macropores (an average pore size about 200 nm) can be observed in the as-prepared materials by SEM and TEM characterization, which provided the dual functions of accelerating the diffusion of gas molecules and providing more reactive sites. The XPS analysis showed that the element Sb existed as Sb5+ in doped samples. Compared with the pure 3D ZnFe2O4 MPs (response = 18), 0.5 % Sb-doped sample presented the response of 35.5–100 ppm n-butanol at 250 °C, and also revealed excellent selectivity and long-term stability to n-butanol. The greatly enhanced sensing performance of Sb-doped simples can be attributed to the construction of 3D spheres with interconnected macroporous structures and the modification of Sb doping. The formation of p-n junctions at interface through Sb doping also improved the sensing performance for n-butanol. In addition, the relative sensing mechanism of Sb-doped 3D ZnFe2O4 MPs for n-butanol sensing has been discussed in detail.