Ultrahigh Surface Area Research Articles

Reinforcing mechanisms review of the graphene oxide on cement composites

Abstract By virtue of the abundant oxygen-functional groups, ultra-high specific surface area and superior mechanical properties, graphene oxide (GO) has been proven as one of the outstanding candidates in cement composites. Compared with the traditional cement pastes, the GO-reinforced cement composites exhibit benefits in pore structure, mechanical properties, and durability. In addition, the abundant oxygen-containing functional groups on GO can promote the hydration rate of cement and combine with hydration products to fill the pores. To further improve the performance of GO-reinforced cement composites and promote the application of composites in practical engineering, it is necessary to comprehensively understand the reinforcing mechanisms of GO on cement composites. In this work, the enhancement mechanisms of GO to improve hydration, nucleation effects, mechanical strengthening mechanisms, antiseepage mechanisms and pore-filling effects of GO are systematically revealed. The optimal dosage range of GO mixing in the current study is calculated by considering the factors of mechanical property and microscopic characterization, but the economic cost also needs to be considered in future development studies. This review will promote the application of the more cost-effective and high-performance GO-reinforced cement composites in practical construction engineering.

Ultrahigh Surface Area Nanoporous Carbons Synthesized via Hypergolic and Activation Reactions for Enhanced CO2 Capacity and Volumetric Energy Density.

We report a family of carbon sorbents synthesized by integrating hypergolics with activation reactions on a templated substrate. The materials design leads to nanoporous carbons with a BET area of 4800 m2 g-1 with an impressive total pore volume of 2.7 cm3 g-1. To the best of our knowledge, this BET area value is the highest reported in the literature. Electron spin resonance (ESR) measurements determined the number of radicals in an effort to provide a mechanistic understanding of the formation of ultrahigh surface area carbons. In combination with XPS, we propose a mechanism based on the synergistic effect between rim-based pentagonal rings and carbon radicals, which we believe can be exploited to produce other highly porous carbons. The CO2 capture capacity of the hyperporous carbon tested under dynamic CO2 capture conditions was ∼1.25 mmol g-1 versus 0.66 mmol g-1 of a conventionally activated carbon under similar conditions. The CO2 capture kinetics were extremely fast and reached 99% of the total capacity within 120 s. Lastly, supercapacitor electrodes deliver a high volumetric energy density of ∼60 W h L-1 and a volumetric power density of 1 kW L-1, which is the highest reported value for activated carbon.

Gas adsorption meets geometric deep learning: points, set and match

Thanks to their unique properties such as ultra high porosity and surface area, metal-organic frameworks (MOFs) are highly regarded materials for gas adsorption applications. However, their combinatorial nature results in a vast chemical space, precluding its exploration with traditional techniques. Recently, machine learning (ML) pipelines have been established as the go-to method for large scale screening by means of predictive models. These are typically built in a descriptor-based manner, meaning that the structure must be first coarse-grained into a 1D fingerprint before it is fed to the ML algorithm. As such, the latter can not fully exploit the 3D structural information, potentially resulting in a model of lower quality. In this work, we propose a descriptor-free framework called “AIdsorb”, which can directly process raw structural information for predicting gas adsorption properties. To accomplish that, the structure is first treated as a point cloud and then passed to a deep learning algorithm suitable for point cloud analysis. As a proof of concept, AIdsorb is applied for predicting CO2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ ext {CO}_{2}$$\\end{document} uptake in MOFs, outperforming a conventional pipeline that uses geometric descriptors as input. Additionally, to evaluate the transferability of the proposed framework to different host-guest systems, CH4\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ ext {CH}_{4}$$\\end{document} uptake in COFs is examined. Since AIdsorb bases its roots on raw structural information, its applicability extends to all fields of material science.

Ultrahigh-surface area covalent organic frameworks for methane adsorption.

Developing porous materials with ultrahigh surface areas for gas storage (for example, methane) is attractive but challenging. Here, we report two isostructural three-dimensional covalent organic frameworks (COFs) with a rare self-catenated alb-3,6-Ccc2 topology and a pore size of 1.1 nanometer. Notably, these imine-linked microporous COFs show both high gravimetric Brunauer-Emmett-Teller (BET) surface areas (~4400 square meters per gram) and volumetric BET surface areas (~1900 square meters per cubic centimeter). Moreover, their volumetric methane uptake reaches up to 264 cubic centimeter (standard temperature and pressure) per cubic centimeter [cm3 (STP) cm-3] at 100 bar and 298 kelvin, and they exhibit the highest volumetric working capacity of 237 cm3 (STP) cm-3 at 5 to 100 bar and 298 kelvin among all reported porous crystalline materials.

Recent Advances of Carbon Capture in Metal-Organic Frameworks: A Comprehensive Review.

The excessive emission of greenhouse gases, which leads to global warming and alarms the world, has triggered a global campaign for carbon neutrality. Carbon capture and sequestration (CCS) technology has aroused wide research interest as a versatile emission mitigation technology. Metal-organic frameworks (MOFs), as a new class of high-performance adsorbents, hold great potential for CO2 capture from large point sources and ambient air due to their ultra-high specific surface area as well as pore structure. In recent years, MOFs have made great progress in the field of CO2 capture and separation, and have published a number of important results, which have greatly promoted the development of MOF materials for practical carbon capture applications. This review summarizes the most recent advanced research on MOF materials for carbon capture in various application scenarios over the past six years. The strategies for enhancing CO2 selective adsorption and separation of MOFs are described in detail, along with the development of MOF-based composites. Moreover, this review also systematically summarizes the highly concerned issues of MOF materials in practical applications of carbon capture. Finally, future research on CO2 capture by MOF materials is prospected.

Hierarchical structural design of cobalt sulphide nanoparticles/nickel sulphide for high-performance supercapacitors

Metal-organic framework (MOF) materials have become increasingly attractive in supercapacitor electrode research because of their regular crystal topology and tunable pore distribution. The strategy for the synthesis of the Ni3S4/Co3S4 electrode material with a layered structure was successfully devised using the layered Ni-MOF as a template and precursor. The characterisation techniques of XRD, FTIR, XPS, SEM, TEM and BET have provided confirmation of the assertion that the Ni3S4/Co3S4 composites exhibit an advanced hierarchical pore structure and considerable specific surface area. The specific capacity of the Ni3S4/Co3S4 composite is as high as 122.8 mAh g−1, and it can still maintain 72.6 % of the specific capacity after 3,000 cycles. Furthermore, the SEM morphology remains largely unchanged after cycling, which demonstrates excellent stability. Moreover, honeycomb-shape porous carbon (N-HAPC) with ultra-high specific surface area was selected as negative electrode material to fabricate a novel hybrid supercapacitor (Ni3S4/Co3S4//N-HAPC), which exhibits a broad operational voltage range of 1.6 V and superior energy density of 28.6 Wh kg−1. Simultaneously, HSCs exhibited remarkable charge-discharge stability, exhibiting a mere 17.2 % decline in capacitance stability following 7,000 GCD cycles. The combination of two Ni3S4/Co3S4//N-HAPC HSCs in series has been demonstrated to be capable of illuminating a small LED lamp, indicating the potential for their use in practical applications. Furthermore, this approach offers a novel strategy for the structural design of MOF-like materials.

Construction of honeycomb-like N-doped porous carbon framework with effective aperture distribution toward advanced supercapacitors and sodium-ion batteries

Smart synthesis of porous carbon with appropriate aperture distribution and high area utilization still retains an enormous challenge for efficient charge storage. Herein, a simple freeze-drying along with subsequent one-step carbonization/activation process is ingeniously devised to fabricate honeycomb-like nitrogen-doped porous carbon (NPC) framework with high-level active N/O-functional groups and hierarchical porous structure including substantial ultra-micropores (<0.7 nm). The underlying formation mechanism of such porous NPC framework is tentatively proposed. By finely regulating the dosage of NaHCO3, the optimized NPC (i.e., NPC114) is endowed with ultra-high surface area utilization of ∼26.4 μF/cm2 at 1 A/g in KOH electrolyte, which is close to theoretical value of electrochemical double-layer capacitance (15 – 25 μF/cm2), and even larger than the case (∼22.4 μF/cm2) with H2SO4 electrolyte due to the inaccessible ultra-micropores by SO42− of larger size. Similarly, as for the organic system, the as-prepared NPC115 with higher meso- and macropore surface area exhibits higher energy density of 22.36 Wh/kg than other counterparts. Furthermore, NPC114, when evaluated as anode material for sodium-ion batteries, exhibited more attractive high-rate Na+-storage properties as well. The in-depth understanding into intrinsic relationship between aperture distribution and electrochemical behaviors will provide meaningful guidance for electrode material design.

Preparation of nano Cu-Mo2C interface supported on ordered mesoporous biochar of ultrahigh surface area for reverse water gas shift reaction

High conversion rate and selectivity are challenges for CO2 utilization through catalytic reverse water gas shift (RWGS) reaction. Herein, a novel mesoporous biochar (MB) supported Cu-Mo2C nano-interface was prepared by consecutive physical activation of coconut shells followed by carbothermal hydrogen reduction of bimetal. As compared with traditional carbon materials, this MB exhibited ultra-high specific surface area (2693 m2 g–1) and mesopore volume of mesopore (0.81 cm3 g–1) with a narrow distribution (2–5 nm), responsible for the high dispersion of binary Cu-Mo2C sites, CO2 adsorption and mass transfer in the reaction system. Moderate carbothermal reduction led to the sufficient reduction of Mo ion with carbon matrix of MB and dispersive growth of nano Cu-Mo2C binary sites (~ 6.1 nm) on the surface of MB. Cu+ species were formed from Cu0 via electron transfer and showed high dispersion with simultaneous boosted bimetal loading due to the strong interaction between nano Mo2C and Cu. These were advantageous to the intrinsic activity and stability of the Cu-Mo2C binary sites and their accessibility to the reactant molecules. Under the RWGS reaction conditions of 500 °C, atmospheric pressure, and 300,000 ml/g/h gas hour space velocity, the CO2 conversion rate over Cu-Mo2C/MB reached 27.74 × 10–5 molCO2/gcat/s at very low H2 partial pressure, which was more than twice that over traditional carbon supported Cu-Mo2C catalysts. In addition, this catalyst exhibited 99.08% CO selectivity and high stability for more than 50 h without a decrease in activity and selectivity. This study offers a new development strategy and a promising candidate for industrial RWGS.Graphical

Wood derived conductive aerogel with ultrahigh specific surface area and exceptional mechanical flexibility for pressure sensing

Conductive nanocellulose aerogels possess durability and sensitivity by using as piezoresistive sensors. Those aerogels are mostly prepared via a “bottom-up” strategy by using nanocellulose or dissolved and regenerated cellulose as raw materials. However, there is a pressing need to further enhance their sustainability and economic viability. To alleviate these issues, cellulose aerogel can alternatively be made via a “top-down” technique that entails the direct removal of contaminants from naturally porous biomass. Herein, conductive aerogels with exceptional mechanical flexibility and ultrahigh specific surface area were created. Delignified wood was partially dissolved and regenerated to created nanocellulose fibrils with spider web structure inside the pores of wood. After modification with silane coupling agent and carbon nanotubes (CNTs), flexible conductive wood aerogel (C-WA) were obtained. The specific surface area of C-WA was as high as 333.82 m2/g, which was 45 times of that of wood. C-WA could maintain its good resilience even after 1000 cycles, showing high compression resilience and excellent fatigue resistance (stress retention rate was 87.22%, height retention rate was 99.5%). The utilization of C-WA as a pressure sensor demonstrated remarkable attributes, including ultra-fast response and stability within the designated range. Furthermore, it exhibited exceptional sensing performance even after enduring 2000 stable cycles. The system is capable of real-time, accurate, and efficient detection of human motion signals, showcasing immense potential for future applications in wearable electronic products.

A controllable self-template synthesis strategy for hierarchical porous carbon microspheres with cavity structures for supercapacitor applications

Herein, we introduce a novel and controllable self-template approach for fabricating hierarchical porous carbon microspheres with cavities (CPCMs). This approach uses polyacrylonitrile (PAN) and acrylamide (AM) microspheres as templates, which feature small anisotropic bumps on their surface. These bumps are encapsulated by divinylbenzene (DVB) during the coating polymerization process. The subsequent hydrolysis of PAN and AM led to the formation of a hierarchical porous structure. Specifically, mesopores mainly arose from PAN hydrolysis, whereas AM contributed additional micropores and macropores, generating an intricate pore structure within the DVB shell. This method differs from traditional pore-making approaches. Additionally, in situ doping of nitrogen (N) and oxygen (O) atoms was achieved. The amount of DVB coating can be adjusted to vary the shell thickness, allowing for the modulation of the pore size distribution and surface micromorphology. Owing to the synergistic effects of an ultrahigh specific surface area (1151.9 m2 g−1), extensive pore volume (1.2575 m3 g−1), and well-structured micro-meso-macropore hierarchy, along with N/O codoping, the resulting carbon material exhibited outstanding electrochemical energy storage performance. Notably, the optimal CPCMs-2 electrode achieves an exceptional specific capacitance of 377 F g−1 at a current density of 0.5 A g−1. This study proposes a novel avenue for designing hierarchical porous carbon materials, and CPCMs could be expanded to a wide range of applications.

Sustainable and Biosafe Approach to Control Potato Late Blight Using Mesoporous Silica Nanoparticles.

Phytophthora infestans-induced potato late blight is considered the "cancer of the potato crop." In this work, mesoporous silica nanoparticles (MSNs) with ultrahigh specific surface area (786.28 m2/g) were synthesized, which significantly inhibited P. infestans compared with some commercial fungicides. Moreover, MSNs inhibited the growth and reproductive of P. infestans processes, including germination, sporangia infection, and zoospore release. MSNs targeted key biological pathways and induced a stress response in the P. infestans, leading to reactive oxygen species (•O2-, •OH, and 1O2) production and structural damage of sporangia. Pot experiments showed that MSNs are translocated from leaves to roots of potato plants, enhancing physiological and biochemical processes, alleviating drought stress, improving resistance to pathogens, and exhibiting soil microbe-friendly. This study systematically reveals the mechanism of MSNs to weaken the reproduction process of P. infestans and confirm the safety and feasibility of MSNs as a green and sustainable fungicide.

Supercapacitor electrodes derived from ultra-high surface area activated carbon spheres synthesized by fluidized activation

This study thoroughly investigated the effects of activation conditions on pore structure development using response surface methodology with a central composite design. The activated carbon sphere (ACS) derived from phenolic formaldehyde resins by carbonization and fluidized activation was examined and characterized. The pore size distribution of ACS samples was all in the microporous and mesoporous scales. ACS with an ultra-high specific surface area of 3142 m2 g−1 and total pore volume of 1.513 cm3 g−1 was successfully obtained at 900 °C for 4 h. Electric double-layer capacitor (EDLC) electrodes derived from ACS with different activation conditions were examined by using cyclic voltammetry and galvanostatic charge/discharge to comprehend the influence of surface area, pore volumes, and the amount of binder on the electrochemical performance. The optimal EDLC electrode was obtained using ACS with the largest specific surface area and pore volume with 5 wt% of binder addition. The specific capacitance was 143.7 F g−1 in a 1 M H2SO4 solution. The cyclical stability of the carbon electrode was also examined under 5000 cycles, and the charge/discharge efficiency remained nearly 100 % without deterioration. This study provides insights into fabricating ultra-high surface area ACS and their potential application as supercapacitors.

Humidity Sensing Properties of Different Atomic Layers of Graphene on the SiO2/Si Substrate.

Graphene has great potential to be used for humidity sensing due to its ultrahigh surface area and conductivity. However, the impact of different atomic layers of graphene on the SiO2/Si substrate on humidity sensing has not been studied yet. In this paper, we fabricated three types of humidity sensors on the SiO2/Si substrate based on one to three atomic layers of graphene, in which the sensing areas of graphene are 75 μm × 72 μm and 45 μm × 72 μm, respectively. We studied the impact of both the number of atomic layers of graphene and the sensing areas of graphene on the responsivity and response/recovery time of the prepared graphene-based humidity sensors. We found that the relative resistance change of the prepared devices decreased with the increase of number of atomic layers of graphene under the same change of relative humidity. Further, devices based on tri-layer graphene showed the fastest response/recovery time, while devices based on double-layer graphene showed the slowest response/recovery time. Finally, we chose devices based on double-layer graphene that have relatively good responsivity and stability for application in respiration monitoring and contact-free finger monitoring.

Balanced adsorption and oxidation in a porous P, N-doped carbon prepared by melt-salt-mediated strategy for enhanced fenton-like reaction

The activation of persulfate oxidation processes using carbon-based catalysts is attractive for eliminating persistent aromatic organic pollutants in wastewater treatment. Herein, N and P co-doped carbonaceous (NPC) catalysts with an ultrahigh surface area were synthesized using a melt-salt-mediated strategy, employing Zeolitic Imidazolate Framework-8 as a self-sacrificing template. The NPC(1:1) carbon, prepared under optimized conditions, exhibited the highest surface area of 2001.5 m2/g, characterized by the highest number of defects and a high dispersion of N (1.89 %) and P (0.30 %) atoms on the carbon. This carbon catalyst exhibited a high capacity for adsorption and potential for activating persulfates in the removal of p-Nitrophenol (p-NP). Experimental data indicate a balance between adsorption and oxidation in the NPC(1:1)/PDS/p-NP system, with the highest catalytic removal rate achieved through moderate pre-adsorption of p-NP. Evidence from quenching, electron paramagnetic resonance (EPR), and amperometric i-t experiments suggests that the NPC(1:1)/PDS system primarily degrades p-NP through an electron transfer pathway. Defects in carbon and graphitic N were identified as catalytic sites. These defects resulted in an electron-deficient state, which leads to the activation of PDS and graphitic N was more reactive than both pyridinic and pyrrolic N in the adsorption of PDS molecules. Additionally, P-containing groups such as C-P-O, C-O-P, and C3-P were pinpointed as active sites on the carbons through DFT calculations. The intermediates during p-NP degradation were identified, and possible degradation pathways were proposed. A toxicity analysis indicated a significant reduction in overall toxicity following the oxidation treatment. This study provides innovative insights into the balance between adsorption and catalytic activity in porous carbon-activated persulfate oxidation reactions, thereby aiding in the development of enhanced oxidation catalysts for environmental remediation.

Stretchable Sweat Lactate Sensor with Dual-Signal Read-Outs.

Innovations in wearable sweat sensors hold great promise to provide deeper insights into molecular level health information non-invasively. Lactate, a key metabolite present in sweat, holds immense significance in assessing physiological conditions and performance in sports physiology and health sensing. This paper presents the development and characterization of stretchable electrodes with ultrahigh active surface area of 648 % for lactate sensing. The as-printed stretchable electrodes were functionalized with an electron transfer layer comprising Toluidine Blue O and multi-walled carbon nanotubes (MWCNTs), and an enzymatic layer consisting of lactate dehydrogenase with β-Nicotinamide adenine dinucleotide as the cofactor for lactate selectivity. This sensor achieves a dual-signal read-out in which both electrochemical and fluorescence signals were obtained during lactate detection, demonstrating promising sensor performance in terms of sensitivity and reliability. We demonstrate the robustness of the dual-signal sensor under simulated conditions of physical deformation and shifted excitation. Under these compromised conditions, the performance of the stretchable electrodes remained largely unaffected, showcasing their potential for robust and adaptable sensing platforms in wearable health monitoring applications.

Preparation of Hierarchical Porous Monoliths With High Surface Areas by a Solvent Knitting Strategy.

Hierarchical porous hypercrosslinked monoliths (PolyHIPE-HCP) with ultrahigh specific surface areas are prepared via a solvent knitting strategy. Compared to previous work, the solvent knitting strategy is carried out in a relatively low air-controlled atmosphere with gradient heating starting from low temperature while using DCM (Dichloromethane) as both a solvent and a cross-linker, allowing for a slow and controlled cross-linking process, thereby achieving a BET surface area ranging from 514 to 728m2g-1. Scanning electron microscopy (SEM) shows that the knitting process does not affect the presence of macroporous structure in the PolyHIPE. With the introduction of mesopores and micropores, these hierarchical porous monoliths exhibit significant potential for applications in gas adsorption and water treatment. Hence, a universal, simple and low-cost method to synthesize polymeric monoliths with hierarchically porous structure and higher surface area is proposed, which has fascinating prospects in industrialization.

Self-sulfur doped mesoporous novel carbon electrodes derived from poly-anthraquinone sulfide for high-performance supercapacitors! A comparative study

Carbon materials are suitable electrode candidates in supercapacitors (SCs) because of their availability, well-defined microstructures, and ultrahigh surface areas. Herein, a universal chemical activation method was utilized to obtain activated carbon (C-KOH) from poly-anthraquinone sulfide (PAQS) at 850 °C and reduced activated carbon (C-KOH-H) from C-KOH via a mild hydrogen reduction process at low temperature. The electrochemical performances of the PAQS derived activated carbon electrodes were investigated by assembling electric double-layer capacitors (EDLCs). Electrodes fabricated from C-KOH and C-KOH-H showed 174 and 182.3 F g−1 specific capacitances at 0.5 A g−1 current density, respectively. Whereas their energy densities were 44 and 46 Wh kg−1 at 350 and 423 W kg−1 power densities, respectively. SCs assembled from C-KOH-H showed excellent rate performance, that retained 140 F g−1 even at high current density (20 A g−1), while the one assembled with C-KOH stored 54 F g−1. Furthermore, the C-KOH-H electrode retained 98 % of the initial capacitance at 1 A g−1 over 20,000 continuous cycles. The experimental results revealed that C-KOH-H showed the best electrochemical performance in SCs, which is attributed to the presence of less sulfur and oxygen than C-KOH after the mild reduction. These results prove that PAQS show excellent activation with KOH to produce well-organized porous activated carbons having high specific surface areas, which can be utilized as high-performance electrode materials in SCs.

Room-temperature synthesis of covalent organic frameworks with dual functional groups for high-performance adsorption of diclofenac sodium from aqueous solution

Diclofenac sodium (DCF) are commonly found in ambient waterways due to its widespread use, and this poses significant risks to both human health and ecosystems. In this study, we have designed and synthesized a series of imine-linked covalent organic frameworks (COFs) with dual functional groups using a triple assembly strategy. Specifically, the platform molecules 2,5-dimethoxyterephthalaldehyde (DMTP), 2,5-dihydroxyterephthalaldehyde (DHTP), and 1,3,5-tris(4-aminophenyl)benzene (TAPB) were employed for the direct fabrication of COFs through Schiff base condensation reactions. As a proof of concept, three room-temperature synthesized COFs (COF TAPB-DMTP-[OH]n, where n represents the molar mass of DHTP, with n values of 0.02, 0.03, and 0.04) were used for DCF adsorption from water. The adsorption isotherms, kinetics, pH effects, ionic strength, co-existing ions, and COF regeneration for DCF were thoroughly investigated. The incorporation of methoxy (-OMe) and hydroxyl (-OH) groups serves as a functional strategy to facilitate hydrogen bonding interactions with DCF molecules. Consequently, the developed COFs, featuring an ultrahigh surface area and mesoporous structure, demonstrated a maximum adsorption capacity of 413.2 mg/g and a rate constant k2 of 0.0435 g/mg/min, which exceeds the performance of the majority of previously described adsorbents. The adsorption capacity toward DCF remained nearly unchanged after five regeneration cycles of the COF. Furthermore, the self-prepared adsorbent demonstrated efficient adsorption of DCF from real environmental water, indicating its potential for practical DCF removal applications.

Highly porous carbon with rich inherent groups for ultrahigh adsorption of organic dyes from wastewater

Activated carbon from renewable biomass or its waste to purify various dyeing wastewater from textile industry is highly desired. In this work, porous activated carbon was prepared by using silk waste as precursor via a simple one-step carbonization process. The obtained SWC-1-800 had ultrahigh adsorption for anionic dye AR73 and cationic dye MB owing to its ultrahigh specific surface area (2774 m2 g−1) and rich functional groups. SWC-1-800 had an increased adsorption capacity reaching 1310 and 928 mg g−1 for AR73 and MB respectively as the initial concentration up to 1000 mg L−1. Moreover, the adsorption capacity was stable under a wide range of Na+ and SDS concentration. By adjusting the temperature and pH value, the maximum adsorption capacity reached 1337 and 1000 mg g−1 for AR73 and MB respectively, keeping the removal rate of AR73 and MB more than 80 % after 5 adsorption cycles. Besides, SWC-1-800 demonstrated quite good adsorption ability for many other kinds of dyes, which adsorption capacity as high as 1998 mg g−1 (Rh B). The adsorption mechanism was further proposed according to the structural characteristics, inherent functional groups and adsorption properties. Using silk waste-derived carbon to effectively absorb the harmful dyes in the wastewater shows dual value for cleaner production via a “waste-waste to clean products” model, which has great application potential in dyeing wastewater purification.

Controllable synthesis of TiO2/graphene composites for human voice recognition in strain sensor.

Low-dimensional materials have demonstrated strong potential for use in diverse flexible strain sensors for wearable electronic device applications. However, the limited contact area in the sensing layer, caused by the low specific surface area of typical nanomaterials, hinders the pursuit of high-performance strain-sensor applications. Herein, we report an efficient method for synthesizing TiO2-based nanocomposite materials by directly using industrial raw materials with ultrahigh specific surface areas that can be used for strain sensors. A kinetic study of the self-seeded thermal hydrolysis sulfate process was conducted for the controllable synthesis of pure TiO2 and related TiO2/graphene composites. The hydrolysis readily modified the crystal form and morphology of the prepared TiO2 nanoparticles, and the prepared composite samples possessed a uniform nanoporous structure. Experiments demonstrated that the TiO2/graphene composite can be used in strain sensors with a maximum Gauge factor of 252. In addition, the TiO2/graphene composite-based strain sensor showed high stability by continuously operating over 1,000 loading cycles and aging tests over three months. It also shows that the fabricated strain sensors have the potential for human voice recognition by characterizing letters, words, and musical tones.