Hierarchical Pore Research Articles

Hybrid plasmonic aerogel with tunable hierarchical pores for size-selective multiplexed detection of VOCs with ultrahigh sensitivity

Sensitive and rapid identification of volatile organic compounds (VOCs) at ppm level with complex composition is vital in various fields ranging from respiratory diagnosis to environmental safety. Herein, we demonstrate a SERS gas sensor with size-selective and multiplexed identification capabilities for VOCs by executing the pre-enrichment strategy. In particular, the macro-mesoporous structure of graphene aerogel and micropores of metal-organic frameworks (MOFs) significantly improved the enrichment capacity (1.68 mmol/g for toluene) of various VOCs near the plasmonic hotspots. On the other hand, molecular MOFs-based filters with different pore sizes could be realized by adjusting the ligands to exclude undesired interfering molecules in various detection environments. Combining these merits, graphene/AuNPs@ZIF-8 aerogel gas sensor exhibited outstanding label-free sensitivity (up to 0.1 ppm toluene) and high stability (RSD=14.8%, after 45 days storage at room temperature for 10 cycles) and allowed simultaneous identification of multiple VOCs in a single SERS measurement with high accuracy (error < 7.2%). We visualize that this work will tackle the dilemma between sensitivity and detection efficiency of gas sensors and will inspire the design of next-generation SERS technology for selective and multiplexed detection of VOCs.

Nanoarchitectonics of self-supporting porous carbon electrode with heteroatoms co-doped: For high-performance supercapacitors

Wood possesses a uniform hierarchical porous structure and high mechanical strength, rendering it an excellent precursor for the preparation of self-supporting carbon electrodes without binders and conductive agents. This paper presents an efficient method for synthesizing a self-supporting carbon electrode (HCW-0.7) with high specific surface area, hierarchical pore structure and abundant surface functional groups, utilizing simple hydrothermal pre-treatment and one-step thermochemical conversion process. The HCW-0.7 electrode demonstrates remarkable electrochemical performance, achieving an excellent specific capacitance of 298.52 F g−1 under a current density of 0.5 A g−1. The wood-based symmetrical supercapacitor (HSC) constructed with HCW-0.7 as the electrode has excellent energy density, power density and rate performance. At the power density of 287.5 W kg−1, HSC demonstrates an energy density of 9.43 Wh kg−1, exhibits its excellent electrochemical performance. Notably, even when subject to a higher power density of 5750 W kg−1, the energy density remains at 5.16 Wh kg−1. Furthermore, even after 20,000 charge and discharge cycles, HSC demonstrates a remarkable capacity retention rate of 96.24 %.

A novel method for preparing anisotropic negative Poisson's ratio composite foam with excellent structural stability and shape recovery property

Negative Poisson's ratio (NPR) foams are usually prepared by the transformation of positive Poisson's ratio (PPR) foams with honeycomb cell structure, which face a challenge for restraining the increase in volume and Poisson's ratio once they are stimulated by high temperature. In addition, they cannot restore to its reentrant structure after large deformation. In this work, a novel method for preparing anisotropic NPR foam with excellent structural stability and shape recovery property is established by synergistically controlling hierarchical pore structures. The obtained NPR silicone rubber/polylactic acid (SR/PLA) composite foam has large-size holes (auxetic structure) with concave hexagonal shape and small-size honeycomb cells, which are generated by 3D printing technology and salt leaching method, respectively. The auxetic structure with the orientation characteristic is directly formed rather than transformed from the honeycomb cell structure. Therefore, the dimension and Poisson's ratio value of the NPR SR/PLA composite foam keep constant after high temperature heating treatment, meaning an excellent structural stability. Furthermore the excellent shape recovery property of the NPR SR/PLA composite foam endows it restore to the initial auxetic structure after large deformation to a large extent. It should be mentioned that the anisotropy of the NPR SR/PLA composite foam further will bring a broad application prospect in the field of human body cushioning materials, such as prosthetic lining sleeve.

Activation of peroxymonosulfate using heterogeneous Fe-doped carbon-based catalyst to generate singlet oxygen for the degradation of sulfamethoxazole

Non-radical catalytic oxidation processes can eliminate refractory pollutants from wastewater containing complex substrates such as dissolved organic matter, but the production of selective non-radicals is challenging during the activation of peroxymonosulfate (PMS). Herein, a novel magnetic carbon-based catalyst (Fe3O4@CD-8, where 8 represents an annealing temperature of 800 ℃) with N and Fe species as catalytic active sites was fabricated to remediate sulfamethoxazole (SMX)-containing water. It showed excellent SMX removal efficiency and facilitated singlet oxygen (1O2) production. The characterization results revealed that Fe3O4@CD-8 had a microscopically hierarchical pore structure and an overall core–shell-like structure. Due to its large specific surface area, N-containing species, and Fe nanoparticles, 0.1 g/L Fe3O4@CD-8 removed almost 100% SMX (24 min) and achieved a 44.1% mineralization (40 min) efficiency in the presence of 0.5 mM PMS. This catalytic system also maintained its removal performance in the presence of inorganic anions and humic acids and over a wide pH range of 3–11, showing good tolerance to various environmental factors. 1O2 was confirmed to be the predominant active species for SMX degradation using the Fe3O4@CD-8/PMS system. Density functional theory (DFT) calculations, intermediate monitoring, and toxicity evaluation demonstrated that SMX was transformed into low-toxicity molecules and completely mineralized into CO2 and H2O. The addition of Fe nanoparticles enhanced PMS adsorption and facilitated the Fe(III)/Fe(II) redox cycle to accelerate the activation of PMS. This study provides new insights and strategies for the controlled production of non-radicals for remediating antibiotic-containing wastewater.

N-doped porous carbon modified by polyacrylic acid for efficient removal of disinfection products in environmental waters under extensive conditions

In this work, a novel porous carbon nanocomposite was successfully prepared by creatively using polyacrylic acid to modify N-doped porous carbon, which was used to adsorb and remove new cyclic chlorine disinfection by-products in various water environments. The high-temperature calcination process at 1000 °C created a hierarchical pore structure that contained both micropores and mesopores. This structure significantly increased the mass transfer efficiency of the target on the adsorbent. The incorporation of N atoms enhanced NC's binding affinity and furnished target adsorption sites. The dispersion of N-doped porous carbon was significantly improved after polyacrylic acid modification. Moreover, the surface charge of NC-1000 was also altered, facilitating easier electrostatic interaction with DBPs. Subsequently, faster adsorption kinetics was obtained within 2 min, and the removal efficiency of 2,4-dichlorophenol (2,4-DCP) and 2,4,6-trichlorophenol (2,4,6-TCP) were promoted to 94.10 % and 98.71 %, respectively. Characterization and data analysis revealed that the primary adsorption mechanism was chemical (electrostatic interaction, hydrophobic interaction, π-π interaction, and hydrogen bond). Surprisingly, factors such as ionic strength, natural organic matter and pH had minimal impact on the adsorption process, indicating that NC-1000@PAA had excellent anti-interference performance. Despite undergoing four adsorption–desorption cycles, NC-1000@PAA upheld a steady composition along with a remarkable adsorption capability. Furthermore, NC-1000@PAA had negligible cytotoxicity, which was assessed by cell experiments. The application of NC-1000@PAA was attested in various environmental waters. The proposed method provided a new strategy to pollutant removal by NC-1000@PAA under extensive conditions, which had wide perspective and practicability on the purification treatment of environmental water.

Promoted catalytic performance from furfural to isopropyl levulinate by Zr loaded on defective nanosponge zeolites

Production of alkyl levulinate (AL) from bio-derived furfural (FUR) is environmental-friendly and sustainable. During such process, bifunctional Zr/zeolite catalyst has been demonstrated highly efficient, in which synergism of metal-zeolite and porous structure of catalysts play important roles. In this work, a defective nanoaponge ZSM-5 zeolite loading Zr catalyst is prepared for conversion of FUR to produce isopropyl levulinate (IPL). The defective nanosponge zeolite is hydrothermally synthesized sequenced by acid treatment (NP-A). Then the Zr species were introduced in the as-synthesized NP-A zeolite by impregnation and calcination (Zr/NP-A). The NP zeolite composed of nano-crystalline aggregates deliver hierarchical pores, which promotes adsorption and activation of isopropanol. And the generation of framework Zr accelerates the adsorption of FUR. The as-synthesized Zr/NP-A catalyst give IPL yield up of 77.8 mol% after 3 h reaction at 200 °C with turnover frequency of 8.3 mmol g−1 h−1, which provides an efficient catalyst for production of AL through bio-route.

High-Density CoSe2 Sites Embedded within 2D Porous N-Doped Carbon for High-Performance Oxygen Reduction Reaction Electrocatalysis.

Designing and fabricating efficient and stable nonprecious metal-based oxygen reduction reaction (ORR) electrocatalysts is a pressing and challenging task for the pursuit of sustainable new energy devices. Herein, porous P-CoSe2@NC electrocatalysts with high-density carbon-coated CoSe2 sites were successfully fabricated based on a pyridyl-porphyrinic metal-organic framework (Co-TPyP MOF) via a molten salt-assisted synthesis method. The hierarchical pore and N-doping carbon substrate of P-CoSe2@NC promotes mass transfer and electron-transfer efficiency, which is beneficial to maximize CoSe2 site utilization. Well-designed P-CoSe2@NC exhibits efficient ORR catalytic activity with a high half-wave potential of 0.863 V and excellent catalytic stability. Meanwhile, rechargeable aqueous primary/quasi-solid-state ZABs based on a P-CoSe2@NC air cathode show a high peak power density and exceptional operating stability, catering to the demands of practical applications. The qualified performance and structure stability of the electrocatalytic system may be mainly attributed to the protection of the CoSe2 nanoparticle by the coated carbon layer. Given the rational design of the structure and the component of the electrocatalyst with enhanced ORR activity, we believe that this work has provided a reliable pathway to the development of high-performance transition-metal chalcogenides for energy-storage and -conversion devices.

MOF-silsesquioxane synergistic modified hybrid porous membrane for high-performance and high-safety lithium battery

As an emerging alternative separator, electrospun PVDF-HFP (polyvinylidene fluoride-hexafluoropropylene) has been widely studied in lithium battery over the years. However, some shortcomings of PVDF-HFP have limited its further application, such as, poor thermal stability, mechanical and electrochemistry properties. In this work, the cage-like silsesquioxanes (CSQ) and metal–organic-framework (MOF) were chemically bound to PVDF-HFP, and a modified hybrid fibrous membrane with hierarchical pore was fabricated. These hybrid groups were successfully introduced into the backbone of PVDF-HFP, which was not only demonstrated by characterization of their chemical structures, and also demonstrated by morphologies and elemental mass spectrometry with the help of scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS). Due to the incorporation of these hybrid groups, the membrane exhibited high thermal stabilities and good flame-retardant performance, and could also play an important role in regulating and improving the migration property of lithium ions and interface performance between electrolyte and electrodes during battery charging/discharging process.

Bioinspired cell membrane-based nanofiltration membranes with hierarchical pore channels for fast molecular separation

Owing to intrinsic perm-selectivity, cell membranes have attracted considerable attention in the field of biomimetic membranes. Herein, largest possible cell membranes of E.coli were prepared and then used as two-dimensional (2D) materials to fabricate high-performance nanofiltration (NF) membranes. The structure parameters of the selective layer of the E.coli-NF membrane could be finely tailored through the loading mass of cell membranes and the applied pressure during vacuum filtration. The E.coli-NF membrane exhibited a high rejection towards dyes (98.5%, brilliant blue R), antibiotics (91.1%, erythromycin), and divalent ions (64.8%, sodium sulfate). The membrane effective pore size was found to be significantly smaller than the interlayer spacing because of the small intrinsic nanochannels inside the E.coli cell membranes, which is distinct from GO and MXene-based 2D membranes. Moreover, the membrane water permeance was 52.6 L m−2 h−1 bar−1, higher than that of most of the reported 2D materials-based NF membranes. The E.coli-NF membrane exhibited the typical separation behavior of the negatively charged NF membranes governed by Donnan effect and size exclusion. This work gives some insights into the fabrication of the selective membranes using cell membranes as 2D materials with intrinsic nanochannels and fruitful choices in nature.

Nano zero-valent iron functioned 3D printing graphene aerogel electrode for efficient solar-driven biocatalytic methane production

To address the urgent need for developing carbon-neutral technologies, microbial electrosynthesis (MES), as an important contributor to the renewable energy field, can convert carbon dioxide to multi-carbon chemicals using microbes serving as living catalysts at the cathode. However, the performance of the cathode is restricted by the weak electrochemical reaction kinetics of the organisms, the specific area of the electrode, and the mass transfer under high current. Herein, we report a facile 3D-printed graphene aerogel (GA) electrode built with a nanozero-valent iron (NZVI)-functionalized graphene ink. The 3D-printed GA electrode was designed to possess hierarchical pores with an enhanced high specific surface area for microbial colonization while ensuring mass transfer. NZVI can assist in-situ hydrogen generation, facilitating biofilm formation and methane (CH4) production in the indirect electron transfer pathway. Consequently, the optimized 3D-printed electrode achieved a maximum CH4 production rate of 6993 ± 832 mmol/m2/d with a faradaic efficiency of 83.7%, which increased by 3.24-fold to the carbon felt electrode. In addition, integrating the proposed cathode into a PV-electrolyzer cell yielded a solar-to-CH4 efficiency of 4.70%. This study provides a unique method for the development of advanced cathodes and underscores the potential of integrating MES with renewable energy technologies.

Ultra-high space utilization of wood/phenolic resin-derived thick carbon electrode for advanced storge devices

The thick electrode design with high packing density of active materials can increase the capacity in a limited space. However, the key challenge is still to develop a system with high space utilization and ensure electron/ion transport in thick electrode. This work proposes an interesting “rebar-concrete” structure, which successfully prepared wood/phenolic resin-derived thick electrode with high space utilization by in-situ polymerization of phenolic resin (concrete) in the wood (rebar) channel. The electrode exhibits an excellent three-dimensional interconnected hierarchical pore structure due to the uniform activation of in-situ anchored KOH particles. The mass loading (35 mg cm−2) and areal capacitance (11F cm−2) of the obtained composite electrode are increased to 446 % and 1257 % of the original balsa wood, respectively. The assembled symmetric supercapacitor (SSC) exhibits a high energy density of 0.63 mWh cm−2 (3.91 mWh cm−3) and an excellent cycle stability (95 % retention after 50 000 cycles), showing good practicability in lighting LEDs or driving a fan. This strategy achieves effective coupling of self-supporting skeleton and powder materials, providing more insights and possibilities for the preparation of high energy density thick electrodes.

A sulfur-rich copolymer hybrid cathode for anchoring polysulfides and accelerating redox reaction in lithium sulfur batteries

In lithium-sulfur batteries (LSBs), sulfur-rich copolymers have attracted wide attention due to the reduced dissolution of active material and alleviated self-discharge problem through the efficient chemical interaction between polysulfide and carbon. Herein, we present an effective strategy to encapsulate sulfur-rich copolymer into NiCo2S4 encapsulated hierarchical porous N/O dual-doped graphitic carbon nanocages (GCNs), named S-DIB@NiCo2S4@PDA@rGO-GCNs. The host NiCo2S4@PDA@rGO-GCNs matrix can not only provide the “lithiophilic”-rich polar sites and tight anchored LiPSnon the N/O dual-doped GCNs surface, and “sulfphilic” NiCo2S4 electrocatalyst for accelerated sulfur electrochemistry, but also offer abundant hierarchical pores for accommodating sulfur and cushioning its volume expansion. Both of the experimental and theoretical analyses reveal the S-DIB@NiCo2S4@PDA@rGO-GCNs possesses the strong chemisorptions and catalytic ability with the synergetic mechanism, suppressing the self-discharge problem. As a proof-of-concept study, the assembled LSBs cells show excellent discharge capacities of 486 and 324 mA h g−1 at 5C and 10C after 1000 cycles, respectively. The corresponding capacity loss rate is as low as 0.032 % and 0.030 % per cycle, respectively. Thanks to the exceptional lithiophilic and sulfiphilic characteristic, the LSBs pouch cell also demonstrates high cycling stability. The proposed hierarchical encapsulation strategy with synergetic chemisorptions and catalytic ability shows great potential for developing advanced electrodes for next-generation high-performance rechargeable batteries.

Nitrogen-Doped Activated Hollow Carbon Nanofibers with Controlled Hierarchical Pore Structures for High-Performance, Binder-Free, Flexible Supercapacitor Electrodes.

Carbon nanofibers (CNFs) are a fascinating electrode material for energy storage devices due to their one-dimensionality, interconnected networks, and chemical stability. However, a relatively low specific surface area of CNFs hinders their use as supercapacitor electrodes. Here, nitrogen-doped hollow CNFs with hierarchical pore structures are prepared via electrospinning of core-shell polymer nanofibers and subsequent carbonization and activation under an ammonia atmosphere. Hierarchical pore structures with micro-, meso-, and macropores are controlled by an ammonia etching effect during the carbonization of polymer nanofibers. In addition, a hollow structure in CNFs is obtained by thermal decomposition of the core polymer during the carbonization/activation. The nitrogen-doped activated hollow CNFs (ahCNFs) exhibited an exceptionally high specific surface area of 3618 m2/g with increased mesopores. Thus, a symmetric supercapacitor using ahCNFs electrodes with a 6 M KOH aqueous electrolyte provides a high specific capacitance of 208 F/g at a current density of 1 A/g, a high energy density of 7.22 W h/kg at a power density of 502 W/kg, a good rate capability, and cyclic stability. Moreover, the freestanding ahCNFs are used for flexible supercapacitor electrodes without any binder. This work demonstrates the great potential of highly porous ahCNFs for high-performance energy storage devices.

Supercapacitors: An Efficient Way for Energy Storage Application.

To date, batteries are the most widely used energy storage devices, fulfilling the requirements of different industrial and consumer applications. However, the efficient use of renewable energy sources and the emergence of wearable electronics has created the need for new requirements such as high-speed energy delivery, faster charge-discharge speeds, longer lifetimes, and reusability. This leads to the need for supercapacitors, which can be a good complement to batteries. However, one of their drawbacks is their lower energy storage capability, which has triggered worldwide research efforts to increase their energy density. With the introduction of novel nanostructured materials, hierarchical pore structures, hybrid devices combining these materials, and unconventional electrolytes, significant developments have been reported in the literature. This paper reviews the short history of the evolution of supercapacitors and the fundamental aspects of supercapacitors, positioning them among other energy-storage systems. The main electrochemical measurement methods used to characterize their energy storage features are discussed with a focus on their specific characteristics and limitations. High importance is given to the integral components of the supercapacitor cell, particularly to the electrode materials and the different types of electrolytes that determine the performance of the supercapacitor device (e.g., storage capability, power output, cycling stability). Current directions in the development of electrode materials, including carbonaceous forms, transition metal-based compounds, conducting polymers, and novel materials are discussed. The synergy between the electrode material and the current collector is a key factor, as well as the fine-tuning of the electrode material and electrolyte.

Facile preparation of poly(melamine formaldehyde) sponge/bacterial nanocellulose composite for oil-water separation

The treatment of a large amount of oil-water mixture generated by oil leakage accidents is an environmental issue that cannot be ignored. Achieving fast and efficient oil-water separation is a goal pursued by both academia and industry. In this paper, poly(melamine formaldehyde) (PMF) sponges were modified by the hydrophilic bacterial nanocellulose (BNC) through mild and facile conditions. With increasing the concentration of BNC dispersion used, the pore size of the composite decreases. The water contact angle of the obtained PMF/BNC composite surface is 0° or so, and the underwater oil contact angle is greater than 150°. Based on its hierarchical pore structure, hydrophilicity and oil repellency, the PMF/BNC composite exhibits excellent oil-water separation efficiency and water treatment flux for layered oil-water mixture (>1.0×107L/(m2·h·bar)). In addition, the PMF/BNC composite also exhibits high water treatment flux and oil-water separation efficiency (> 95%) for oil-water emulsion with and without surfactant. Stacking several composite slices could achieve higher oil-water separation efficiency.

Free-Standing Hierarchically Porous Silica Nanoparticle Superstructures: Bridging the Nano- to Microscale for Tailorable Delivery of Small and Large Therapeutics.

Nanoscale colloidal self-assembly is an exciting approach to yield superstructures with properties distinct from those of individual nanoparticles. However, the bottom-up self-assembly of 3D nanoparticle superstructures typically requires extensive chemical functionalization, harsh conditions, and a long preparation time, which are undesirable for biomedical applications. Here, we report the directional freezing of porous silica nanoparticles (PSiNPs) as a simple and versatile technique to create anisotropic 3D superstructures with hierarchical porosity afforded by microporous PSiNPs and newly generated meso- and macropores between the PSiNPs. By varying the PSiNP building block size, the interparticle pore sizes can be readily tuned. The newly created hierarchical pores greatly augment the loading of a small molecule-anticancer drug, doxorubicin (Dox), and a large macromolecule, lysozyme (Lyz). Importantly, Dox loading into both the micro- and meso/macropores of the nanoparticle assemblies not only gave a pore size-dependent drug release but also significantly extended the drug release to 25 days compared to a much shorter 7 or 11 day drug release from Dox loaded into either the micro- or meso/macropores only. Moreover, a unique temporal drug release profile, with a higher and faster release of Lyz from the larger interparticle macropores than Dox from the smaller PSiNP micropores, was observed. Finally, the formulation of the Dox-loaded superstructures within a composite hydrogel induces prolonged growth inhibition in a 3D spheroid model of pancreatic ductal adenocarcinoma. This study presents a facile modular approach for the rapid assembly of drug-loaded superstructures in fully aqueous environments and demonstrates their potential as highly tailorable and sustained delivery systems for diverse therapeutics.

The effect of hierarchical pore structure SAPO-34 catalyst on the diffusion and reaction behavior in MTO reaction

Establishing the hierarchical pore structure is considered as a feasible approach for enhancing diffusion and improve catalytic efficiency of SAPO-34 zeolite in the methanol-to-olefin process. Nevertheless, under reaction conditions, the correlation among the diffusion behavior in the crystal, coke deposition behavior and catalytic performance of SAPO-34 catalysts with varying pore structures remains to be clarified. Herein, we revealed the structure–activity relationship between the hierarchical pore structure, the catalytic performance and the anti-coke deposition performance of the catalyst in the MTO reaction via the synergy of reaction–diffusion experiments and molecular simulation, then the mechanism of the hierarchical pore SAPO-34 catalyst to eliminate the diffusion limit and improve the accessibility of acid sites was clarified. The results demonstrated that the establishment of a hierarchical pore structure strengthened the diffusion of reactant methanol in the pores, leading to the diffusion resistance being reduced by 5 times and the diffusion coefficient being improved by two orders of magnitude. The key reaction rate-determining step shifted from micropores diffusion to the adsorption of acid sites in hierarchical pores, and the catalytic efficiency of the catalyst was increased by 3 times. Furthermore, with the establishing hierarchical pore technique, the expansion of the accommodation space for coke deposition led to a reduction in the blocking of pores due to coke deposition, particularly around the orifices. Moreover, the accessibility of the reactant molecules to the acid sites within the pores was enhanced, resulting in a balanced ratio between pore blockage and acid site coverage, thereby improving the anti-coke deposition performance of the SAPO-34 catalyst. This work can provide important foundational data and theoretical guidance for the study of reaction–diffusion synergistic interaction in zeolite catalysis reactions.

Retrievable Hierarchically Porous Ferroelectric Ceramics for “Greening” the Piezo‐Catalysis Process

AbstractPowder‐based piezo‐catalysis, as an effective approach to degrade wastewater and produce hydrogen from water splitting, has been widely used in the field of energy conservation and pollution reduction. However, these hard‐to‐recycle powders pose a challenge of secondary pollution in the environment. As a result, this paper provides an alternative strategy based on the manufacture of porous ceramics as a green chemistry approach to replace ferroelectric powders currently used in traditional piezo‐catalysis. The piezo‐catalytic properties of Ba0.75Sr0.25TiO3 (BST) ceramics prepared using freeze casting and direct ink writing techniques are investigated in detail. The positive effect of introducing micro‐ and macro‐pores is explored and discovered, where a BST ceramic with hierarchical pore channels is prepared by a combination of direct ink writing and freeze casting and exhibts the highest first‐order kinetic rate constant per mass of catalysts, k, of up to 2.91 min−1 kg−1 compared to bulk BST ceramics. This study therefore provides the first report for the benefits of hierarchical porous ferroelectric ceramics used in water splitting, with an average H2 production rate reaching 848.88 nmol g−1 h−1.

Morphology and structure control of lignin-derived hierarchical porous carbon for high-performance supercapacitors

Lignin-derived porous carbon (LDPC) is a low-cost and sustainable electrode material for supercapacitors. However, the complex three-dimensional amorphous structure of lignin brings challenges to the morphology and structure control of LDPC, which limits the electrochemical performance of these electrodes. Herein, a series of LDPCs with different particle morphologies and hierarchical pore structures are prepared by spray drying and KOH activation. It is found that the morphology and structure of LDPCs can be effectively controlled by adjusting the spray drying temperature and KOH ratio. A systematic investigation has been conducted on the relationship between the morphology and structure of LDPCs and their electrochemical performance. The preferred LDPC exhibits excellent electrochemical performance, showing high specific capacitances of 372.5 F g−1 and 264.8 F g−1 at current densities of 0.2 A g−1 and 20 A g−1, respectively, in the three-electrode test. The symmetric supercapacitor assembled with the LDPC electrode material exhibits superior cycling stability and energy density. After 10000 cycles of continuous charging and discharging at current density of 1 A g−1, the specific capacitance retention is as high as 96.4%. When the power density is 493.3 W kg−1, the energy density reaches ∼9.1 Wh kg−1. This work offers a viable method for regulating the morphology and structure of LDPC electrode material for high-performance supercapacitor application.

Self-single-doped hierarchical porous carbon nanofiber derived Alpinia galanga stem-based for boosted supercapacitor performance

In this study, activated carbon with hierarchical pores and a nanofiber structure doped with oxygen was prepared using a pure biomass-based sustainable strategy involving integrated chemical impregnation and pyrolysis. Alpinia galangal stem was chosen as it functions as fast conductive network with abundant electrochemical active sites for high-grade electrode materials. The optimal precursor exhibited self-doping of oxygen ranging from 6.15 to 15.69 % with 1065.58 m2/g, which contributed to the redox reaction of the electrode material. When tested in a 2-electrode system, the porous carbon nanofibers showed a high specific capacitance of 226F g−1 at 1 A g−1 in 1 M H2SO4 electrolyte, producing an energy density of 9.3483 Wh kg−1 with a coulombic efficiency of 89.01 %. The results showed that oxygen-doped hierarchical porous carbon nanofibers produced from Alpinia galangal stem biomass and designed to be solid-free of binders are highly promising as high-quality electrode materials that can improve sustainable supercapacitor performance.