Hierarchical Porous Materials Research Articles

Hierarchical porous carbon composite constructed with 1-D CNT and 2-D GNS anchored on 3-D carbon skeleton from spent coffee grounds for supercapacitor

In recent years, biomass-derived carbon electrode materials for energy storage have attracted intensive attention in terms of their natural unique structure, widespread availability and low cost. Herein, a unique hierarchical porous carbon composite material (CGCM@GNS&CNT) was facilely constructed on 3-D carbon skeleton by anchoring 2-D graphene nanosheet (GNS) and 1-D carbon nanotube (CNT) through self-assembling method. The CGs with abundant macroscopic pores were utilized as 3D carbon skeleton, CNT and GNS anchored on them were applied to enhance the specific surface area (SSA) and electrical conductivity. The composite material exhibits large SSA of 460 m2 g−1, interconnected conductive network and inherent N, O doping. The CGCM@GNS&CNT electrode achieves a high areal capacitance of 441 mF cm−2 and volumetric capacitance of 90 F cm−3 at 1 mA cm−2 in 1.5 M Na2SO4 electrolyte. More importantly, the CGCM@GNS&CNT-based symmetric supercapacitor affords a remarkable energy density of 31 μWh cm−2 at a power density of 800 μW cm−2 in 1.5 M Na2SO4. The capacitance retention and coulombic efficiency can retain 102.5% and 100.5% over 2000 cycles, respectively, confirming its superb charge/discharge stability and long-term reversibility. These signify that CGCM@GNS&CNT material holds a considerable promise for electrode application in high-performance supercapacitor.

Preparation of high-performance, three-dimensional, hierarchical porous carbon Supercapacitor materials and high-value-added potassium Humate from cotton stalks

Although the resource utilization of organic solid waste from biomass (OSWB) has been investigated, it is difficult to completely utilize such resources using the existing methods. Therefore, the development of a comprehensive application method would be very significant. Here, a simple process using chemical oxidation of H2O2 was initially developed to prepare potassium humate (HA-K) from cotton stalk peels. Subsequently, we obtained three-dimensional hierarchical porous carbon (3D-HPC) materials by carbonizing and activating the residue after HA-K extraction. Chemical oxidation achieved the effect of “killing two birds with one stone” because it increased the HA-K yield by 40% and the capacitance of the electrode based on 3D-HPC (3OCA-500-650). Compared with the electrode without chemical oxidation, the obtained 3OCA-500-650 exhibited higher specific capacitance (420 F g−1 at 0.5 A g−1), enhanced an energy density (58 Wh kg−1 at a power density of 1300 W kg−1). This work provides a green, facile technology to achieve full utilization of OSWB, which is expected to be effective and scalable for preparing HA-K and electrochemical energy storage materials exhibiting excellent performance.

Soluble salt assisted synthesis of hierarchical porous carbon-encapsulated Fe3C based on MOFs gel for all-solid-state hybrid supercapacitor

Hierarchical porous materials receive extensive attention due to their excellent electrode kinetic performance. Herein, a facile strategy is presented to fabricate hierarchical porous supercapacitor materials using NaCl-assisted MOFs gel as a structure-directing template. By controlling the additive amount of NaCl, hierarchical porous carbon-encapsulated Fe3C with tailored pore size distribution has been obtained with a high specific capacity of 184.1 mAh g−1 (602.3F g−1) at a current density of 1 A g−1. The analysis of kinetics and impedance indicates that the tailored porosity can provide broad ion diffusion pathway and low charge-transfer resistance. Meanwhile, seawater was used instead of NaCl for preparing hierarchical porous carbon with good capacitive performance. When evaluated their practical applications, the assembled all-solid-state hybrid supercapacitor delivers a high energy density of 30.6 W h kg−1 at a power density of 600 W kg−1, and even maintains an energy density of 15.5 W h kg−1 at a power density of 12000 W kg−1 with 86.5% capacity retention after 10,000 cycles. This work is anticipated to open up a new route of using MOFs gel and water-soluble salts for designing hierarchical porous electrodes materials, which pave the way for advanced utilization of MOFs gel and seawater.

Enantioselective SERS sensing of pseudoephedrine in blood plasma biomatrix by hierarchical mesoporous Au films coated with a homochiral MOF

Here, we present a new family of hierarchical porous hybrid materials as an innovative tool for ultrasensitive and selective sensing of enantiomeric drugs in complex biosamples via chiral surface-enhanced Raman spectroscopy (SERS). Hierarchical porous hybrid films were prepared by the combination of mesoporous plasmonic Au films and microporous homochiral metal-organic frameworks (HMOFs). The proposed hierarchical porous substrates enable extremely low limit of detection values (10−12 M) for pseudoephedrine in undiluted blood plasma due to dual enhancement mechanisms (physical enhancement by the mesoporous Au nanostructures and chemical enhancement by HMOF), chemical recognition by HMOF, and a discriminant function for bio-samples containing large biomolecules, such as blood components. We demonstrate the effect of each component (mesoporous Au and microporous AlaZnCl (HMOF)) on the analytical performance for sensing. The growth of AlaZnCl leads to an increase in the SERS signal (by around 17 times), while the use of mesoporous Au leads to an increase in the signal (by up to 40%). In the presence of a complex biomatrix (blood serum or plasma), the hybrid hierarchical porous substrate provides control over the transport of the molecules inside the pores and prevents blood protein infiltration, provoking competition with existing plasmonic materials at the limit of detection and enantioselectivity in the presence of a multicomponent biomatrix.

Ordinary filter paper-derived hierarchical pore structure carbon materials for supercapacitor

Adopting filter paper as precursor, combined with a facile carbonization and activation process at a relative low temperature of 650°C, a regular and hierarchical porous carbon electrode materials are obtained to assemble high performance supercapacitor. The PFPC40 supercapacitor exhibits a high specific capacitance of 219.6 F∙g−1 and 173.0 F∙g−1 at 1 A∙g−1 and 50 A∙g−1, respectively, indicating an excellent rate capability of 78.8%. In addition, the capacitance retention of PFPC40 supercapacitor reaches 99.0% after ten thousand charge-discharge cycles at 5 A∙g−1, demonstrating excellent cycling stability. Furthermore, the PFPC40750 sample possesses a high specific surface area (SSA) of 1920 m2∙g−1, and the good electrochemical performance is similar to that of PFPC40. Therefore, this work provides a new strategy for the preparation of hierarchical porous carbon electrode material and this material is promising to applied in energy storage device.

Enhancing extraction performance of organophosphorus flame retardants in water samples using titanium hierarchical porous silica materials as sorbents

A sorbent for the extraction of organophosphorus flame retardants has been proposed, based on UVM-7 (University of Valencia Materials) mesoporous silica doped with titanium. Designed cartridges have been applied to the extraction and preconcentration of flame retardants in water samples, followed by gas chromatography coupled to a mass spectrometry detector. Firstly, UVM-7 materials with different contents of titanium were synthesized and characterized by several techniques, thus confirming the proper mesoporous architecture. The potential of these materials was assessed in comparison with their morphological properties, resulting Ti50-UVM-7 the best solid phase. Several extraction parameters were also optimized. Analytical parameters were also evaluated, and limits of detection from 0.019 to 0.21 ng mL−1 were obtained, as well as intra-day relative standard deviation below 11% for all analytes. Extraction efficiencies above 80% in water samples were achieved. The reusability of the material was also proved. Finally, the designed protocol was applied for the analysis of real water samples, and quantifiable concentrations of tris(2-chloroisopropyl) phosphate (TCIPP), tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) and triphenyl phosphate (TPhP) were obtained in some samples. The method was compared with a United States Environmental Protection Agency general method with C18 cartridges.

An Energy and Power Dense Aqueous Zinc-Ion Hybrid Supercapacitor with Low Leakage Current and Long Cycle Life

Imparting high energy density to already power dense capacitor leads to hybrid supercapacitor (SC), which is most sought after in automobile, heavy-duty electronics application, and internet of things. The hybrid SCs with lithium or sodium ion chemistry demand organic electrolytes for their operation, which is environmental unfriendly and poses fire-hazard. As an alternative, here we report a low cost and highly safe energetic hybrid SC based on zinc-ion chemistry operated in 3 M ZnSO4 with high surface area (1018 ± 4 m2 g−1) hierarchical porous carbon cathode material derived from the Tamarindusindica seeds (ACTS-800), a bio-source. The hybrid SC demonstrates a maximum energy density of 127 (± 3) Wh kg−1 (254 μWh cm−2) at 0.1 A g−1 and power density of 7920 (± 24) W kg−1 (15.84 mW cm−2) at 10 A g−1. Besides having excellent power/energy density values, ∼ 100% capacity retention over 5000 galvanostatic charge/discharge cycles was observed. The most interesting feature of this SC is its low open-circuit voltage decay (34% in 60 h) and low leakage current density (11 mA g−1), which allows it to hold charge for longer duration qualifying it as one of the best aqueous SC known in the literature.

Thermal properties of three-dimensional hierarchical porous graphene foam-carbon nanotube hybrid structure composites with phase change materials

Developing novel shape-stabilized phase change materials (ssPCMs) is of vital importance for efficient utilization of thermal energy. In addition, elucidation of the host–guest interaction mechanism is a prerequisite for the methodical design and synthesis of ssPCMs. Here, we prepared a new hierarchical structure, porous graphene foam-CNT hybrid structures (GCNTs), to serve as matrix materials. Micropores and mesoporous channels were introduced during the reassembly of graphene foam and carbon nanotubes (CNTs). PEG was filled into the GCNTs via the solution impregnation method to prepare composite PCMs, whose structural and phase change properties were evaluated via FTIR, XRD, BET, and DSC. A theory was proposed that large pores improve loading capacity, while small pores improve supporting-immobilization capacity. The radius of gyration as well as the melting and diffusion processes were analyzed using molecular dynamics (MD) simulation methods, which revealed that PEG resides in the composite its flexibility is enhanced and the PEG molecules favor the formation of an amorphous liquid layer near the pore walls, resulting in decreased melting point and latent heat. MD simulations also indicated that PEG molecules form a liquid layer near pore walls and crystallize at the pore center. The highest loading rate achieved in the composites was 80 wt%, although the corresponding surface area was far below that of graphene foam due to the hierarchical porous structure. This study will provide insights into the host-guest interaction mechanism in porous composite materials and the design of novel composite phase change materials with improved phase change properties according to the design of suitable hierarchical porous materials.

Self-assembled polypyrrole hierarchical porous networks as the cathode and porous three dimensional carbonaceous networks as the anode materials for asymmetric supercapacitor

Herein, we report the phytic acid (PA) mediated self-assembled polypyrrole (PPy) networks by one-pot fabrication step for energy storage application. Simultaneous interaction of PPy segments with PA via hydrogen bonding and electrostatic interaction results in the formation of hierarchical porous electrode material. Electrochemical data exhibited PA-assisted synthesized PPy network showed the improved capacitance about 775.3 F g−1 at 1 A g−1 which was significantly higher compared to its corresponding counterpart, PPy (without PA) that showed only 473.5 F g−1, indicating the key role of PA in designing the electrode materials. Three-dimensional porous electrospun carbon nanofibers (P@3D-CNFs) prepared by the modified gas-foamed method were used as a negative electrode material which exhibited 205.5 F g−1 at 1 A g−1 current density. Further, the assembled device (PPy@PA//P@3D-CNFs) exhibited delivery of a maximum specific energy (44.8 Wh kg−1) at a specific power (850.0 W kg−1) with excellent cycling stability (84%) after 5,000 charges/discharge cycles. This work expects to deliver a new strategy to make asymmetrical supercapacitor device with high specific energy and superior stability from the PA assisted PPy networks as the cathode and porous carbon networks as the anode materials.

Functionally integrated g-C3N4@wood-derived carbon with an orderly interconnected porous structure

The synthesis of highly orderly hierarchical porous functional materials has always been a significant challenge in materials science. Herein, we employed natural materials to fabricate graphite carbonitride@wood-derived carbon (g-C3N4@WDC) with a micro-nano scale ordered interconnection porous structure using a simple two-step method and achieved the corresponding application dimensions. g-C3N4@WDC has the unique advantages of a wide pore size distribution, high ordered degree range, low manufacturing cost, and excellent mechanical strength. Furthermore, we have shown the heterotopic functional integration of the sample in photocatalysis and supercapacitors. As a result, excellent photocatalytic efficiency and high electrochemical capacity are obtained. These attributes meets the targets of green chemistry and sustainable development. This work is a demonstration of functionally integrated g-C3N4@WDC with an ordered interconnection porous structure and paves the way for using natural structures to prepare materials with high nanostructural-control and multifunctional integration for use in energy storage, adsorption, photocatalysis, environmental rehabilitation, oil–water separation, or other applications.

Effect of Vesicle Structure on Catalytic Activity of Suzuki‐Miyaura Cross‐Coupling Reaction: Impact of Framework and Morphology

AbstractA novel hybrid porous polymer with hollow vesicle structure has been synthesized via Friedel‐Crafts alkylation reaction and solvent‐induced method. The resulting two‐dimensional networks are hierarchical porous materials with high Brunauer‐Emmett‐Teller (BET) surface area of 1582 m2 g−1. The vesicle structure directly influenced the activity and shaping the performance of the catalyst. The kinetic study reveals the special vesicle structure can enrich the substrates in a limit scope and increase the reaction rate. It has been demonstrated that the framework and morphology play a major role on the catalysts’ excellent performance in Suzuki–Miyaura cross‐coupling reaction of aryl chlorides. These findings help elucidate the mode action of the vesicle structure in the unrevealed Suzuki reaction mechanism of supports and the potential development of new morphology control catalysts.

Synthesis and processing optimization of N-doped hierarchical porous carbon derived from corncob for high performance supercapacitors

• Porous carbon has been synthesized by pyrolysis methods using corncob as precursor. • Nitrogen-doped hierarchical porous carbon shows high gravimetric capacitances. • The symmetric device shows high energy density and good electrochemical stability. • This method holds great promise for low-cost and high performance supercapacitors. In this paper, N-doped hierarchical porous carbon-based supercapacitor electrode materials have been synthesized by means of pyrolysis methods using corncob, KOH and urea as biomass sources, activator and nitrogen source, respectively. The influence of carbonization temperature on the morphology and structure and N doping content on supercapacitor performance of corncob derived porous carbons has been investigated systematically. The specific capacitance of sample with carbonization temperature at 800 °C and urea: corncob mass ratio of 4:3 reaches 382.6 F/g at 0.5 A/g, and still maintains as high as 232.7 F/g at high current density of 20 A/g. The symmetric supercapacitor achieves a high energy density of 18.84 Wh/kg at power density of 149.36 W/kg in 6 M KOH aqueous electrolyte. It also shows excellent cycling stability with a 95.16% capacitance retention after 10,000 cycles. The results demonstrate that these as-prepared corncob-derived activated carbons have a great prospect in low-cost and high-performance supercapacitors.

Nitrogen‐doped hierarchical few‐layered porous carbon for efficient electrochemical energy storage

AbstractLarge surface area, high conductivity, and rich active site of carbon electrode materials are necessary characteristics for energy storage devices. However, high conductivity and high nitrogen doping of carbon electrode materials are difficult to coordinate. Here, a facile method via the carbonization of nitrogen‐containing Schiff base polymer has been developed to prepare high conductivity and high nitrogen‐doped hierarchical porous carbon. The organic components with a benzene ring structure in the polymer promote the formation of more sp2‐graphitized carbon, which is beneficial for the improvement of electrical conductivity. Nitrogen‐doped hierarchical porous carbon calcined at 900°C under the NH3 atmosphere possesses high nitrogen content of 7.48 at%, a large specific surface area of 1613.2 m2/g, and high electrical conductivity of 2.7 S/cm. As electrode materials in an aqueous‐based supercapacitor, nitrogen‐doped hierarchical porous carbon exhibits superior specific capacitance of 385 F/g at 1 A/g as well as excellent rate performance (242 and 215 F/g at a current density of 100 and 200 A/g, respectively). In addition, the specific capacitance of electrode measured in a two‐electrode system is 335 F/g at 1 A/g, and the long‐term cycling stability can be achieved with more than 94% initial capacitance after 10 000 cycles. The constructed symmetric supercapacitor delivers high energy density and high power density. The outstanding electrochemical performances combined with the novel and scalable synthetic approach make the nitrogen‐doped hierarchical porous carbon potential electrode material for electrochemical devices.

Fluffy Cotton-Like GO/Zn–Co–Ni Layered Double Hydroxides Form from a Sacrificed Template GO/ZIF-8 for High Performance Asymmetric Supercapacitors

The combination of carbon materials and active metal materials can prepare newly fashioned and hierarchical porous materials. Meanwhile, the combined action of the two materials can effectively opt...

Hierarchically porous zirconium dioxide dual-templated by acacia mangium tannin extract and an amphiphilic triblock copolymer

In this article, a new hierarchical porous zirconia material with adjustable pore size is fabricated by using biomass materials of acacia mangium tannin extract (AMTE) and amphiphilic triblock copolymer poly(ethylene glycol)-blockpoly(propylene glycol)-block-poly(ethylene glycol) (P123) as a dual-template for the first time. All the raw materials we used are non-toxic and the synthesis process is relatively simple, low-cost, eco-friendly, and reproducible, which is suitable for large-scale production. Characterization using SEM, N2 sorption isotherm, and Mercury intrusion porosimetry indicate that hierarchical porous ZrO2 combining abundant mesopores and macropores was synthesized successfully using P123 and AMTE as a dual template. Significantly, dual-templated ZrO2 with hierarchical porosity has an advantage over single-templated samples in protein adsorption, especially for the large-sized proteins. Furthermore, the real sample test shows the synthesized material with a multidimensional porous structure displays the potential for practical protein wastewater treatment.

Hierarchical multi-shell hollow micro\u2013meso\u2013macroporous silica for Cr(VI) adsorption

The development of easier, cheaper, and more effective synthetic strategies for hierarchical multimodal porous materials and multi-shell hollow spheres remains a challenging topic to utilize them as adsorbents in environmental applications. Here, the hierarchical architecture of multi-shell hollow micro–meso–macroporous silica with pollen-like morphology (MS-HMS-PL) has been successfully synthesized via a facile soft-templating approach and characterized for the first time. MS-HMS-PL sub-microspheres showed a trimodal hierarchical pore architecture with a high surface area of 414.5 m2 g−1, surpassing most of the previously reported multishelled hollow nanomaterials. Due to its facile preparation route and good physicochemical properties, MS-HMS-PL could be a potential candidate material in water purification, catalysis, and drug delivery. To investigate the applicability of MS-HMS-PL as an adsorbent, its adsorption performance for Cr(VI) in water was evaluated. Important adsorption factors affecting the adsorption capacity of adsorbent were systematically studied and Kinetics, isotherms, and thermodynamics parameters were computed via the non-linear fitting technique. The maximum capacity of adsorption computed from the Langmuir isotherm equation for Cr(VI) on MS-HMS-PL was 257.67 mg g−1 at 293 K and optimum conditions (pH 4.0, adsorbent dosage 5.0 mg, and contact time 90 min).

Highly efficient tungsten-doped hierarchical structural N-Enriched porous carbon counter electrode material for dye-sensitized solar cells

In this study, a novel hierarchical hybrid of tungsten species nanoparticles anchored on nitrogen-doped hollow mesoporous carbon (WC/N-HHMC) with high surface area and hierarchical porosity is synthesized and investigated as a noble metal-free counter electrode (CE) for dye-sensitized solar cells (DSSCs). The unique characteristics such as co-doping of graphitic nitrogen and tungsten species nanoparticles, high specific surface area, and interconnected hierarchical porosity render WC(0.7)/N-HHMC an alternative of Pt-based CE for DSSCs. The tungsten species serve as high electrocatalytic activity centers providing available active sites for regeneration of I−/I3− electrolyte, while N-HHMC endows a high-speed transport pathway to facilitate the electron transfer from carbon skeleton to active sites. Electrochemical investigations indicate that WC(0.7)/N-HHMC electrode displays excellent electrocatalytic activity for I3− reduction due to lower charge-transfer resistance (RCT) at CE/electrolyte interface. Benefiting from the above advantages, a DSSC based on WC(0.7)/N-HHMC CE shows an energy conversion efficiency of 8.0%, which is superior to that of cell assembled with platinized CE (7.8%). More remarkably, WC(0.7)/N-HHMC exhibits a good electrochemical stability toward I−/I3− redox reaction. The present study demonstrates the rationality for preparation of inexpensive WC(0.7)/N-HHMC electrocatalyst with special structures and its application as a great alternative to Pt-based CE for DSSCs.

Hierarchical Porous Molybdenum Carbide Based Nanomaterials for Electrocatalytic Hydrogen Production.

The electrocatalytic hydrogen evolution reaction (HER) for the preparation of hydrogen fuel is a very promising technology to solve the shortage of hydrogen storage. However, in practical applications, HER catalysts with excellent performance and moderate price are very rare. Molybdenum carbide (MoxC) has attracted extensive attention due to its electronic structure and natural abundance. Here, a comprehensive review of the preparation and performance control of hierarchical porous molybdenum carbide (HP-MoxC) based catalysts is summarized. The methods for preparing hierarchical porous materials and the regulation of their HER performance are mainly described. Briefly, the HP-MoxC based catalysts were prepared by template method, morphology-conserved transformations method, and secondary conversion method of an organic-inorganic hybrid material. The intrinsic HER kinetics are enhanced by the introduction of a carbon-based support, heteroatom doping, and the construction of a heterostructure. Finally, the future development of HP-MoxC based catalysts is prospected in this review.

Facial preparation of hierarchical porous Ba(B2Si2O8) microsphere by sacrificial-template method and its highly efficient selective adsorption of triphenylmethane dyes

Hierarchical porous materials exhibit a superb adsorptive performance owing to the merits of large surface area. In this work, novel uniform Ba(B2Si2O8) microspheres with hierarchical porous nanostrucrure constructed by ultrathin nanosheets have been prepared through a facile hydrothermal method using dendritic mesoporous silica nanospheres as sacrificial-template, and the corresponding formation mechanism was also proposed. XRD, FT-IR, SEM and TEM techniques were used to characterize prepared samples. The as-fabricated Ba(B2Si2O8) microsphere exhibited excellent absorption performance for triphenylmethane (TPM) dyes because of its large surface area and the abundant porosity, which can selectively adsorb for acid fuchsin (AF), malachite green (MG), and basic fuchsin (BF) with the adsorption capacities of 2460.54, 992.24 and 57.95 mg g−1, which are much higher than those of most reported adsorbent materials. The adsorption process was found to comply with the pseudo-second-order rate equation and Freundlich adsorption model. Moreover, the competitive adsorption, adsorption thermodynamics, and recycling performance were also investigated, respectively. Due to its larger adsorption capacity and good reusability, Ba(B2Si2O8) microsphere could be considered as a highly efficient absorbent for triphenylmethane dyes from pollutional water.

Nanoscaled Fractal Superstructures via Laser Patterning—A Versatile Route to Metallic Hierarchical Porous Materials

AbstractA laser‐based procedure for the preparation of metallic hierarchical porous materials is introduced and exemplified on tin, copper, silicon, titanium, and tungsten surfaces to demonstrate its general applicability. The impact of suitably tuned nanosecond laser pulses triggers a process in which laser‐induced metal ablation and instantaneous recondensation of partially oxidized metals lead to cauliflower‐like superstructures comprising a hybrid micro‐/nanopatterning. Repeated scanning with the intense focused beam over the surface creates microstructures of hierarchically tunable porosity in a layer‐by‐layer design. The 3D morphology of these superstructures is analyzed using tomographic data based on focused ion‐beam scanning electron microscopy to return a fractal dimension of Df = 2.79—practically identical to a natural cauliflower (Df ≈ 2.8), even though the plant is four orders of magnitude larger than the superstructures generated through the laser process. The high Df value signifies a complex morphology that boasts a huge external surface. The introduced concept enables convenient access to a variety of metallic hierarchical porous materials, which are key to performance in environmentally and technologically relevant areas like energy generation, storage, and conversion, as well as sensing and catalysis.