High Surface Area Research Articles

Construction of nitrite electrochemical sensor by in-situ deposition of FeOOH nanomaterials on carbon cloth modified with green DBD technology

The treatment of carbon cloth with concentrated or dilute acid to produce hydrophilic carbon-based flexible electrodes raises environmental pollution concerns. This study utilized a green, rapid, and cost-effective dielectric barrier discharge (DBD) technique was utilized for the hydrophilic modification of conductive hydrophobic carbon cloth. A nitrite electrochemical sensor was constructed by depositing high specific surface area pom-pom FeOOH on modified carbon cloth through a constant potential electrochemical in-situ deposition method. The FeOOH/CC binder-free self-supporting electrode demonstrates nitrite detection capabilities within linear ranges of 0.5–900 µM and 1 mM–10 mM, boasting a detection limit of 0.154 µM (S/N = 3). This sensor exhibits excellent interference immunity, stability, and reproducibility. Its application in detecting nitrite in ham sausage and tap water samples yields 97.00 % to 101.33 % recovery rates, respectively, comparable to UV spectrophotometry results, affirming the sensor’s accuracy and practical feasibility. This straightforward and swift carbon material modification technique presents a novel approach for crafting carbon cloth electrochemical sensors.

Ti-doped synergistic hollow thin-walled Bi2O3 nano-microspheres for efficient tetracycline hydrochloride photodegradation

Bismuth oxide (Bi2O3) has been extensively investigated in the fields of environmental photocatalysis, owing to its exceptional charge transport performance and remarkable resistance to photocorrosion. However, the limited absorption spectrum of light and rapid recombination of photogenerated charge results in a low quantum efficiency. Herein, an efficient photocatalytic system for tetracycline hydrochloride (TCH) photodegradation based on titanium (Ti)-doped hollow, thin-walled Bi2O3 with nano-microspheres is fabricated via a facile self-assembly strategy. It is shown that doping Ti in Bi2O3 can generate oxygen vacancies, in addition, the addition of Ti in the solvothermal process inhibits the conversion of Bi3+ to bismuth at high temperature, making the content of each component in the heterostructure controllable. The hybrid catalyst exhibits superior performance in visible-light-driven photocatalytic degradation of TCH (about 95.1 % degradation efficiency after 120 min) and excellent stability (up to 4 cycles) under visible light irradiation. The optimized catalyst exhibits excellent performance in visible light catalytic degradation, owing to the synergistic effect of high specific surface area, Bi plasma resonance effect and charge mobility. Moreover, the photocatalytic mechanism of Ti-Bi2O3 have been deeply analyzed through experimental investigation and DFT theoretical calculations. The findings contribute to the synthesis of efficient visible-light-driven Bi-based photocatalysts and to the understanding of photocatalytic degradation reactions.

Structural modification of CNT-C xerogel through synthesis parameters

This study focuses on the synthesis of porous carbonaceous structures by drying resorcinol-formaldehyde (RF) gels under ambient conditions and then carbonizing them in an inert atmosphere. This avoids the expensive drying processes like supercritical drying or freeze drying. However, drying under ambient conditions does cause structural shrinkage and a reduction in porosity and specific surface area. Therefore, the goal of this study was to compensate for these structural degradations by adjusting other synthesis and process parameters, such as solvent exchange, drying condition, content of water, catalyst, and CNT in the gel. In the present study, different organic solvents such as t-butanol, ethanol, and acetone were used to replace the water in the hydrogels at a certain R/F molar ratio (1:2). The experimental results showed that t-butanol, with its low surface tension, resulted in a structure with a high specific surface area and pore volume. Regarding the catalyst dosage, by changing the R/C molar ratio between 71 and 849, the best structural properties were obtained using R/C∼200. Increasing the water content from 15 to 30 mL led to a decrease in specific surface area and pore volume. Drying the gel at an oven temperature of 85 °C resulted in the highest specific surface area, pore volume, and mean pore diameter. Increasing the dosage of carbon nanotubes (CNTs) in the range of 20–150 mg led to an increase in total pore volume and mean pore diameter. The results of this work can be a step forward towards the industrialization of these materials in various applications.

One-step construction of MWCNTs@MoS2@Chitosan film for ciprofloxacin sensing and its oxidation mechanism

Ciprofloxacin (CIP), extensively used in medical, agricultural, and forestry sectors as an antibiotic, poses risks of water contamination due to misuse or improper disposal, highlighting the pressing necessity for accelerated detection methods. Hydrophilic multi-walled carbon nanotubes (MWCNTs) and molybdenum disulfide (MoS2) were co-dispersed in a chitosan (CS) solution, which facilitates film formation. The high specific surface area of MWCNTs, coupled with the excellent semiconducting properties of MoS2 and the overall hydrophilicity of the composite nanomaterial film, markedly increases the active sites and reaction contact area. Subsequently, a drop-coating method was used to fabricate a MWCNTs@MoS2@Chitosan film onto the surface of a glassy carbon electrode (GCE) for CIP detection spanning from 0.50 to 1200.00 µmol/L using Differential Pulse Voltammetry (DPV), achieving a limit of detection (LOD) of 0.16 µmol/L. Simultaneously, the sensor demonstrates excellent reproducibility, stability, and selectivity. In several real water samples, the sensor performance was verified using a spiked recovery method. And in three water samples the recoveries ranged from 98.38 to 113.53 %, with a relative standard deviation (RSD) of less than 4.80 %. Meanwhile, the accuracy of these result was verified using UV–visible (UV–vis) spectroscopy. Furthermore, we proposed an electrooxidation mechanism for CIP that involves a reaction with two electrons and two protons.

One-step high-efficiency microwave synthesis of N-doped bamboo biochar for tetracycline degradation

N-doped bamboo biochar (NBB) was successfully synthesized through one-step, rapid pyrolysis (e.g., 10 min) using urea and urea nitrate impregnated bamboo particles exposed to low power (e.g., 460 W) microwave radiation. NBB-460 exhibited high specific surface area of 876.1 m2/g and outstanding catalytic performance for tetracycline hydrochloride (TCH) degradation. The TCH degradation efficiency reached to 94.3 % with the optimized catalytic condition (i.e., 0.2 g/L NBB-460, 3 mM PMS, 50 mg/L TCH, 25 ℃, without pH regulation). The density functional theory calculation showed that the graphitic nitrogen and pyridinic nitrogen of NBB-460 served as active sites for peroxymonosulfate activation and TCH degradation. The quenching test, electron paramagnetic resonance spectra, and electrochemical measurements indicated that tetracycline hydrochloride underwent degradation via radical (O2•−), non-radical (1O2) pathways, and surface electron transfer. This study introduces an energy-efficient and time-effective method for converting biomass to N-doped biochar as highly efficient peroxymonosulfate activator for environmental applications.

A critical review of recent advancements in zinc based metal organic framework nanocomposites and their derivatives for supercapacitor applications with future perspectives and challenges

Among various energy storage materials, Zinc-based metal-organic frameworks (Zn-MOFs used as precursors, templates, and shape controllers) act as potential candidates for supercapacitor (SC) applications due to their remarkable properties, such as facile preparation methods, high specific surface area (SSA), large porosity, outstanding power (Pden) & energy density (Eden), astonishing crystallinity, adjustable sizes, exceptional chemical & thermal stability, elongated life-cycle, framework diversity, and tunable structures. The present review focuses on the most recent progress on pristine Zn-MOFs, nanocomposites (with graphene (Gr), carbon nanotubes (CNTs), and polyaniline (PANI)), and their derivatives (metal oxides (MOs) & hydroxides (MHOs), porous carbon (PC) & activated carbon (AC), and metal sulfides (MSs)) as electrode materials to present the most up-to-date overview in this specific field. We first discuss the fundamental charging mechanisms (electric double-layer capacitance and pseudocapacitance) and the electrochemical techniques (cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy) of SCs. We then analyzed different methods with advantages and disadvantages of Zn-based MOF synthesis, such as solvothermal, hydrothermal, sonochemical, microwave heat-assisted, simple stirring, slow evaporation, mechanochemical, and electrochemical. Furthermore, structural, morphological, and electrochemical assessment techniques of reported Zn-based MOFs were examined in detail in three- and two- electrode configurations (asymmetric/symmetric devices with power and energy density). Finally, the ongoing issues and future developments in this field for architecturing supercapacitive devices are also discussed.

The synergistic enhancement of photocatalytic activity by Fe3O4–TiO2 nanosheets for rhodamine B degradation

As an advanced oxidation material, Fe3O4-TiO2 nanocomposites have been widely used in wastewater treatment. However, conventional Fe3O4 nanoparticles suffer from drawbacks such as carrier recombination and aggregation, which seriously affect the catalytic activity. In this study, Fe3O4-TiO2 nanosheets with different TiO2 loading rates were synthesized by sol-gel method and solvothermal method. The unique two-dimensional nanostructure of Fe3O4 nanosheets facilitated the deposition of TiO2 nanoparticles, resulting in Fe3O4-TiO2 nanosheets with a high BET specific surface area of 121.67 m2·g−1. Under optimal experimental conditions, the degradation rate of RhB dye in the photocatalytic synergistic Fenton-like system constructed with Fe3O4-TiO2 nanosheets reached 98.12 % within 120 min, significantly surpassing that of single photocatalysis and Fenton-like systems. It was attributed to the unique surface structure of Fe3O4 nanosheets, which provided a larger contact area for TiO2 nanoparticles. It facilitated the effective reduction of Fe3+ to Fe2+ by photogenerated electrons in TiO2, inhibited the recombination of photogenerated electron-hole pairs, and consequently enhanced the degradation rate of RhB dye. Furthermore, Fe3O4-TiO2 magnetic nanosheets exhibited excellent reusability and stability, with the recovery rate and degradation rate of RhB dye remaining above 90 % even after five cycles. More importantly, the catalytic mechanism of Fe3O4-TiO2 nanosheets was elucidated, and •OH identified as the primary reactive species responsible for degrading RhB dye. This work provides a novel research direction for designing and preparing advanced catalytic degradation materials, offering a practical solution to the challenging issue of wastewater treatment.

A high-sensitivity and multi-response magnetic nanofiber-aerogel sensor with directionally aligned porous structure based on triple network for interactive human–machine interfaces

Flexible multimodal sensors with a porous structure have attracted tremendous attentions due to their low density, high specific surface area, a wide detection range and satisfied deformability. However, pores disorder and maldistribution issues of these multimodal sensors are major concerns during their sensing response, which often cause poor linearity and unstable sensing characteristics. Herein, a facile and rapid approach was proposed to fabricate a multifunctional magnetic sensor with directionally aligned porous structure based on triple network by combining electrospun nanofibers, bidisperse magnetic particles and sodium alginate/chitosan foam. The electrospun nanofibers were employed as three-dimensional skeletons for the crystallization and vertical growth of ice crystals. Benefiting from the remarkable structure orientation, the homogenized nanofiber-aerogel scaffold possesses excellent flexibility, superior deformation recoverability and biocompatibility. The assembled sensors not only exhibit a high sensitivity (0.40 T−1), rapid response/recovery time and long stability under magnetic stimuli, but also displays satisfied cross-sensitivity, quick response and reliable durability (8000 cycles) in response to external mechanical functions. Importantly, the respective input stimuli could be clearly discriminated via outputting the electrical signals of opposite or different trends. Furthermore, the sensor could be employed as wearable skins to monitor various physiological signals and realize information translation by Morse mode for individuals with disabilities. Additionally, a wearable gesture recognition system with assistance of the deep learning algorithm was testified, with high average recognition accuracy of 99 %. The simple fabrication process and prominent multifunctional characteristics of the proposed sensor endow it with an extensive application prospect in the field of interactive human–machine interfaces.

Cooperation mechanism between the vacuum levels and interface dipole energy of triboelectric materials for real-time vibration recognition

Triboelectric Nanogenerator (TENG) device, acting as sensors of energy harvesting and material identification, are attracting intensive attention. Nevertheless, vibration wave recognition cannot be achieved by the developed devices owing to device structure and working mechanism limitations. Here, a cooperation mechanism between the vacuum level and interface dipole energy of triboelectric materials is proposed to explore triboelectric charge generation and migration. Hence, metallized cottons of high specific surface area encapsulated by polydimethylsiloxane (PDMS) of low elastic modulus are developed as TENG-based sensors to realize vibration recognition. The results indicate electrons flow from PDMS to metallized cotton with the generation of an extremely thin interfacial dipole barrier layer because the vacuum level of metallized cotton is higher than that of PDMS, resulting in the accumulation of triboelectric charges on the PDMS surface under vibration, further leading to generating distinct triboelectric signals that can be simply differentiated using signal amplitude or peak shape with 98.3% recognition accuracy for vibration waveform. Besides, combined with the deep machine learning and triboelectric effect, a vibration perception system integrated with a TENG-based sensor, data processing and display modules is also developed for real-time vibration monitoring. This work contributes to further clarifying the theoretical mechanisms of triboelectric charge excitation under vibration.

Development and characterization of ZIF-8/WS2 composites for NH3 detection at room temperature

This study successfully synthesized zeolitic imidazolate frameworks-8 (ZIF-8) particles and tungsten disulfide (WS2) nanosheets, forming ZIF-8/WS2 composites via a layer-by-layer filtration adsorption method. The morphological and structural characterization results revealed that ZIF-8 particles and WS2 nanosheets effectively combine under filtration to form a hierarchical film structure. Room temperature ammonia (NH3) detection results indicated that the ZIF-8/WS2 composites-based gas sensor, due to the high specific surface area (1458 m2/g) and strong gas adsorption capability of ZIF-8, exhibits response intensity to NH3 that is 4.98 times higher than that of pure WS2 nanosheets. Additionally, it demonstrated stable response and recovery curves with short response/recovery times (113.5 ± 3.9 s/115.0 ± 1.9 s). This work provides valuable insights and inspiration for the construction of composite materials involving 2D TMDs and the enhancement of their room-temperature gas sensing performance.

Constructing novel Sn-Mo bimetallic sulfide heterostructures for enhanced catalytic performance towards the hydrogen evolution reaction

Understanding the design principles of efficient electrocatalysts using the structure–activity relationship is crucial for the advancement of energy-related applications, and specifically the hydrogen evolution reaction (HER). Non-precious electrocatalysts with low overpotentials are essential for driving the HER and achieving high energy efficiency. In this study, we synthesized and thoroughly investigated various heterostructures combining Mo and Sn sulfides, ranging from complete phase-separated hybrids to homogeneous mixtures: SnS@MoS2 core–shell structures, SnS/MoS2 with edge-rich Mo and (SnxMo1-x)S with uniformly distributed Sn-Mo. Our findings reveal that the SnS@MoS2 structure exhibited relatively high intrinsic activity characterized by a high electrochemical active surface area and rapid charge transfer kinetics, thereby enhancing the HER catalytic performance. The presence of fluffy MoS2 layers provided an abundance of optimized sites for HER, potentially due to strain and defects such as S vacancies, known as active catalytic sites. The optimal structure facilitated efficient charge transfer from the core to the shell, improving conductivity and catalytic activity. Our research highlights the advantages of a core–shell hybrid structure, offering guiding principles for the development of an optimal SnS@MoS2 catalyst.

CeO2/ZrO2 p-n Heterojunction Nanostructures for Efficient NO2 Gas Sensing

In a recent while, heterostructured materials have shown great potential for highly sensitive and selective gas sensing applications. Herein, CeO2–ZrO2 nanocomposites were fabricated in varying compositions in lower CeO2 region (2.5–10%) via hydrothermal methodology. UV-visible DRS studies ascertained the band gap tailoring of the heterojunctions ranging from 3.33-4.07eV as compared to their pure counter parts CeO2 (3.03eV) and ZrO2 (4.96eV). The surface area studies revealed the high specific surface areas of 90, 81.2, 72.7 and 61 m2/g for the 2.5, 5, 7.5 and 10% CeO2–ZrO2 hetero-nanocomposites along with 53.2 and 108 m2/g for pure CeO2 and ZrO2 nanostructures, respectively. CeO2–ZrO2 nanocomposites revealed ameliorated sensing response towards the NO2 as compared to the bare ZrO2. The maximum sensitivity of 1572 was shown by the 5% CeO2–ZrO2 nanocomposite at optimum operating thermal conditions of 250oC that was relatively higher as compared to pristine ZrO2 nanospheres. Augmented sensing efficiency is attributed to the tweaked surface area of the nanocomposites, alleviated band energy, existence of oxygen vacant sites over CeO2 surface and ameliorated interaction due to the formation of CeO2–ZrO2 heterojunctions. The improved sensing performance of CeO2–ZrO2 sensors has been extensively discussed alongside mechanistic sketch.

Rapid removal of polycyclic aromatic hydrocarbons from water using sulfonated mesoporous polymeric adsorbents

Polycyclic aromatic hydrocarbons (PAHs) are potential hazards and are often found in aquatic environments through industrial effluents. Herein, we report sulfonated modified mesoporous thermoplastic polymers to remove potentially carcinogenic PAHs from water rapidly. Mesoporous structures of the thermoplastics (polystyrene, polysulfone, and polycarbonate) were attained using nano-crystallization induced phase separation by flash-freezing route. Sulfonation reactions carried out hydrophilic surface modifications of the polymers. Their ion exchange capacity (IEC) values determined the degree of sulfonation. The sulfonated mesoporous polymers were characterized using Fourier-Transform Infra-Red spectroscopy (FT-IR) for functional groups, Field-Emission Scanning Electron Microscopy (FE-SEM) for mesoporous structures, Brunauer-Emmet-Teller method for specific surface area, and Barrett-Joyner-Halenda method for pore size distributions. The IEC values for the sulfonated mesoporous polymers range from 1.13 – 1.15 × 10-2 meq. g−1. The sulfonated mesoporous polymers showed high specific surface areas (176–185 m2/g) with pore sizes ranging from 5 nm to 9 nm. The sulfonated mesoporous polymers rapidly adsorb PAHs from nearly saturated water solutions within 60 min with % removal of over 98 %. The adsorbents can also be easily regenerated by simple washing with methanol and are found to be recycled up to 10 cycles with only a marginal reduction in adsorption capacities

Design of high-performance wood-derived N-doped ECR electrocatalysts based on Marcus theory

Electrochemical reduction of CO2 over wood-derived metal-free N-doped carbon electrocatalysts provides a new route for converting CO2 into value-added fuels However, it is a challenge to efficiently design and screen high-performance electrocatalysts. In this paper, we combined the Marcus equation with the theory of thermal-kinetic correlation to successfully predict the optimal N-C doping ratio. Poplar wood -derived 3D N-doped graphitized carbon with optimal N doping content (pyridine-N 1.87 at%, pyrrole-N, 1.52 at%), high specific surface area (471.2 m2 g−1), and abundant nanopores were successfully obtained with the assistance of melamine (N source), which exhibited a high ECR activity of 86.78 % at a low applied potential of −0.71 V (vs. RHE) and long-term stability of at least 10 cycles. This extends the application of the Marcus equation and improves new ideas for the future design of high-performance electrocatalysts.

NH2-MIL-88B@TP-TA@CuS for photothermal catalytic synergistic antibacterial activity

Reactive oxygen species (ROS) provide a promising way to fight bacterial infection and meet the persistent challenge of antibiotic resistance. Nanoenzyme mimics natural enzyme and becomes an effective regulator of ROS level. In this study, NH2-MIL-88B with high specific surface area was selected as the core, and the covalent organic skeleton material TP-TA COF was wrapped by "sequential growth" technology. Subsequently, through the second hydrothermal treatment, the inorganic material CuS with excellent photothermal performance was integrated into the outer layer, and the NH2-MIL-88B@TP-TA@CuSX composite nanoenzyme was synthesized. Different from the traditional nano-enzyme, NH2-MIL-88B@TP-TA@CuSX nano-enzyme still has good catalytic effect under neutral conditions (pH=7). In addition, NH2-MIL-88B@TP-TA@CuSX has good near infrared (NIR) absorption rate and high photothermal conversion efficiency (PTCE is 48.7 %), which can be used for photothermal treatment (PTT) of bacteria. Mild photothermal effect can further enhance the enzyme-like catalytic activity of NH2-MIL-88B@TP-TA@CuSX, so that H2O2 can be more efficiently catalyzed to produce a large number of ROS. The experimental results in vitro show that NH2-MIL-88B@TP-TA@CuSX can effectively kill Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) in the presence of laser irradiation and H2O2.

Design and fabrication of reduced graphene oxide (RGO) incorporated NiCo2S4 hybrid composites as electrode materials for high performance supercapacitors

One of the most promising bimetallic sulphides for use in energy-storage systems is NiCo2S4, but further research is required to give it a high reversibility and electrochemical reaction capacity. In this study, we show the rational materials design of an ideal NiCo2S4 nanoparticle as a NiCo2S4/RGO nanocomposite, embedded in a reduced graphene oxide (RGO) matrix. NiCo2S4 nanoparticles, which ranged in size from 20 to 25 nm and were firmly fixed on the surface of RGO sheets, made up the produced composite. As predicted, the produced nanocomposite displayed a high specific surface area, a mesoporous structure, and high conductivity, resulting in a large electroactive area and rapid electron and ion motion. Additionally, we present the advancements in material science, showcasing the NiCo2S4/RGO nanocomposite electrode, which has a long cycle life of 5000 cycles, a high capacitance retention of 85.6 %, and an exceptional specific capacitance of 1505 Fg-1 at 1 Ag-1. A high active-material loading asymmetric supercapacitor serves as an example of the real-world use. The NiCo2S4/RGO nanocomposite exhibits an exceptional 48 Whkg-1 energy density at a power density of 985 Whkg-1, while maintaining a high power density of 7227 Wkg-1 density of 25 Whkg-1. The exceptional stability and electrochemical efficiency of the NiCo2S4/RGO nanocomposite validate that our methodical materials science and technology optimisation in the areas of active substance synthesis, electrode expansion, and device design/fabrication will help advance the development of high-performance supercapacitors in future years.

Cooperation mechanism between the vacuum levels and interface dipole energy of triboelectric materials for real-time vibration recognition

Triboelectric Nanogenerator (TENG) device, acting as sensors of energy harvesting and material identification, are attracting intensive attention. Nevertheless, vibration wave recognition cannot be achieved by the developed devices owing to device structure and working mechanism limitations. Here, a cooperation mechanism between the vacuum level and interface dipole energy of triboelectric materials is proposed to explore triboelectric charge generation and migration. Hence, metallized cottons of high specific surface area encapsulated by polydimethylsiloxane (PDMS) of low elastic modulus are developed as TENG-based sensors to realize vibration recognition. The results indicate electrons flow from PDMS to metallized cotton with the generation of an extremely thin interfacial dipole barrier layer because the vacuum level of metallized cotton is higher than that of PDMS, resulting in the accumulation of triboelectric charges on the PDMS surface under vibration, further leading to generating distinct triboelectric signals that can be simply differentiated using signal amplitude or peak shape with 98.3% recognition accuracy for vibration waveform. Besides, combined with the deep machine learning and triboelectric effect, a vibration perception system integrated with a TENG-based sensor, data processing and display modules is also developed for real-time vibration monitoring. This work contributes to further clarifying the theoretical mechanisms of triboelectric charge excitation under vibration.

Boosting the performance of dye-sensitized solar cells by employing Li-substituted NiO nanosheets as highly efficient electrocatalysts for reduction of triiodide.

Dye-sensitized solar cells (DSSCs) exhibit considerable potential as a promising technology, particularly when addressing the challenge of replacing the costly Platinum (Pt) counter electrode (CE) with economically viable and chemically stable CE materials. This study examines the use of two-dimensional hexagonal-shaped nickel oxide nanosheets substituted with varying mol% of lithium (1, 3, and 5%) (Li (1-5%)-NiO NSs) as the counter electrode (CEs) for DSSCs. The facile hydrothermal method was employed for the preparation of NiO and Li (1-5 mol%)-NiO samples. The BET analysis of NiO and Li (1-5%)-NiO indicates that higher concentrations of Li1+ ions in Ni2+ ions sites lead to an increase in the overall surface area of NiO. This leads to an elevated number of exposed electrocatalytic active sites which resulted in enhancing the rate of reduction of ions. The cyclic voltammetry (CV) result of 5 mol% of Li substituted NiO (5-LNO) shows outstanding electrocatalytic activity towards the redox reaction of redox mediator among the as-prepared CEs. The DSSCs assembled with 5-LNO CE show an excellent power conversion efficiency (η) of 5.84% with short-circuit current ( of 18.76 mAcm-2, and open-circuit voltage ( of 0.80 V which is higher than Pt-based CE (η of 4.05% with of 10.16 mAcm-2, and of 0.69 V). The DSSCs fabricated with 5-LNO CE exhibit excellent photovoltaic performance because of their high active surface area and enhanced electrical conductivity. The 5-LNO CE has low cost, significant electrocatalytic activity, less toxicity, and superior device efficiency than NiO, other Li (1-3%)-NiO, and Pt CEs, making it a suitable candidate for Pt-free DSSCs application.

New insights into the resistance of silica aerogel to temperature up to 1200 °C

Silica aerogel (SA) with high specific surface area (903 m2/g) and pore volume (6.81 cm3/g) was synthesized via base-catalyzed one-step sol–gel process. Thermal stability of SA under high temperature was estimated from structure evolution with temperature and time. The results demonstrate that the SA is thermally stabile at 1000 °C within 120 min (leaving specific surface area of 286 m2/g and pore volume of 1.46 cm3/g) and 1200 °C within 30 min (leaving specific surface area of 129 m2/g and pore volume of 0.59 cm3/g). The research provides new insights into the resistance of silica aerogels to high temperature, which is significant for application under harsh conditions.

Tailoring microstructure and conductivity of porous hollow carbon spheres to enhance their performance as electrode materials for supercapacitors

Porous carbon materials are widely used in electrical double-layered capacitors for energy storage applications due to their abundant pores, high specific surface area and excellent electrochemical stability although their intrinsic electrical conductivity is generally low. Traditional high-temperature treatment was always adopted to boost the electrical conductivity of porous carbon materials by enhancing their graphitization degree, while this would always be accompanied by severe damage to pore structure and corresponding electrochemical performance. To solve the dilemma between boosting electrical conductivity and retaining pore structure, in this research, we proposed a low-temperature catalytic graphitization for hollow carbon spheres (HCSs) prepared by modified Stöber method accompanied with a special pore structure tailoring strategy. By altering the timing of adding carbon source, followed by secondary pore-forming and catalytic graphitization, HCSs with thin and porous shell walls along with enhanced conductivity were synthesized. Compared with the untreated HCSs or high-temperature graphitized HCSs, HCSs fabricated by the aforementioned combined strategies exhibited enhanced pore volume, specific surface area (2160.1 m2·g-1, 165.3% of the untreated group) and conductivity (16.44±0.05S·cm-2, 221.5% of the untreated group), demonstrating much better electrochemical performance as the mass specific capacitance reached 256.7F·g-1 and a volume specific capacitance reached 102.7F·cm-3 at a current density of 1A·g-1. Moreover, due to the largely promoted conductivity, the capacitance with the catalytic graphitized HCSs as the electrode material could be further boosted up to 273.4F·g-1 at 1A·g-1 by exempting the generally indispensable conductive agents and a high capacitance retention of 100.7% was achieved after 5000 cycles at a relatively high current density of 10A·g-1. This could be attributed to local graphitization brought by dispersed catalyst particles instead of entire atom rearrangement during high-temperature graphitization which would result in severe pore vanishing. The synergy of low-temperature catalytic graphitization and secondary pore-forming might be a novel strategy in electrode material fabrication for advanced supercapacitors or other energy storage devices.