Iridescent Colloidal Crystals Composed of SiO2 Porous Hollow Sphere for SERS Application.

In recent years, the application of low-refractive-index materials in the optical field has attracted considerable attention due to it high transmittance and high optical sensitivity. In this study, we synthesized SiO2 porous hollow spheres (SPHS) with an ultralow refractive index (n = 1.05) by using a templating method. Their refractive indices could be easily controlled from 1.05 to 1.08 by tuning the thickness of shell. In addition, a droplet coatings method is proposed for SPHS colloidal crystal (CC) by controlling the temperature and humidity. The SPHS CCs displayed distinct structural colors when the incident angle was adjusted and demonstrated high angular resolution. Moreover, the iridescent color changes could be observed with the naked eye. For surface-enhanced Raman scattering application, more analyte could be absorbed by the porous shells, and metal nanoparticles were coated on the SPHSs surface to increase the hot spot density for improving the SERS intensity.

Lentibacillus saliphilus. sp. nov., a moderately halophilic bacterium isolated from a saltern in Korea.

A novel moderately halophilic bacterial strain, designated YIM 93176T, was isolated from a saltern in Korea and subjected to a polyphasic taxonomic study. This isolate YIM 93176T was observed to grow in the presence of 0-22% (w/v) NaCl and at pH 6.0-10.0 and 10-45 °C; optimum growth was observed with 5-10% (w/v) NaCl and at pH 7.0-9.0 and 28-37 °C. Based on 16S rRNA gene sequences analysis, the nearest relatives were Lentibacillus alimentarius M2024T (96.5% similarity), followed by Virgibacillus carmonensis LMG 20964T (96.0%) and the other type strains of the family Bacillaceae, but phylogenetic analysis indicated that strain YIM 93176T belonged to the cluster comprising type species of the genus Lentibacillus. Genome sequencing of strain YIM 93176T revealed a genome size of 3.2 Mb and a DNA G + C content of 40.5 mol%. The major fatty acids were anteiso-C15:0 (40.7%) and iso-C15:0 (26.4%), while the predominant respiratory quinone was menaquinone 7. The polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. These genotypic and chemotaxonomic characteristics supported affiliation of strain YIM 93176T to the genus Lentibacillus. In addition, phenotypic characteristics could distinguish strain YIM 93176T from its closely related species in genus Lentibacillus. Based on the cumulative evidences from the polyphasic taxonomic study, strain YIM 93176T represents a novel species of the genus Lentibacillus, for which name Lentibacillus saliphilus sp. nov. (type strain YIM 93176T = CCTCC AB 208139T = DSM 21375T) is proposed.

Green and Highly-Efficient Microwave Synthesis Route for Sulfur/Carbon Composite for Li-S Battery.

Multiporous carbons (MPCs) are prepared using ZnO as a hard template and biomass pyrolysis oil as the carbon source. It is shown that the surface area, pore volume, and mesopore/micropore ratio of the as-prepared MPCs can be easily controlled by adjusting the ZnO/oil ratio. Sulfur/MPC (S/MPC) composite is prepared by blending sulfur powder with the as-prepared MPCs followed by microwave heating at three different powers (100 W/200 W/300 W) for 60 s. The unique micro/mesostructure characteristics of the resulting porous carbons not only endow the S/MPC composite with sufficient available space for sulfur storage, but also provide favorable and efficient channels for Li-ions/electrons transportation. When applied as the electrode material in a lithium-ion battery (LIB), the S/MPC composite shows a reversible capacity (about 500 mAh g-1) and a high columbic efficiency (>95%) after 70 cycles. Overall, the method proposed in this study provides a simple and green approach for the rapid production of MPCs and S/MPC composite for high-performance LIBs.

Crystal growth in dentinal tubules with bio-calcium carbonate-silica sourced from equisetum grass.

BACKGROUND/PURPOSE: One effective way to deal with dentin hypersensitivity is to develop materials to seal the tubules. The porous bio-calcium carbonate-silica (BCCS) contained well-dispersed CaCO3 would form calcium phosphates to seal the dentinal tubules when mixed with an acidic solution. The acidic hydrothermal treatment and calcination to isolate the BCCS from the agricultural waste like equisetum grass was used, which would be more environmentally friendly than chemically synthesized mesoporous biomaterials. The aim of this study was to develop mesoporous materials from natural resources to occlude the dentinal tubules which could be more environmentally-friendly. METHODS: Dentin disc samples were prepared and treated with different methods as follows: (1) BCCS mixed with H3PO4; (2) BCCS mixed with KH2PO4; (3) Seal & Protect® was used as a comparison group. Sealing efficacy was evaluated by measuring the depths and percentages of precipitate occlusion in dentinal tubules with SEM. RESULTS: The N2 adsorption-desorption isotherm of the BCCS demonstrated a pore size of around 15.0 nm and a surface area of 61 m2g-1. From the results of occlusion percentage and depth, the BCCS treated with H3PO4 or KH2PO4 demonstrated promising sealing efficacy than the commercial product. CONCLUSION: This synthetic process used the agricultural waste equisetum grass to produce bio-calcium carbonate-silica would be environmentally friendly, which has great potential in treating exposed dentin related diseases.

Adsorption and reactions of propenoic acid and 2-fluoropropanoic acid on Cu(100) and O/Cu(100).

X-ray photoelectron spectroscopy, reflection-absorption infrared spectroscopy, and temperature-programmed reaction/desorption have been employed to investigate the adsorption and reaction pathways of CH2=CHCOOH and CH3CHFCOOH on Cu(100) and oxygen-precovered Cu(100) [O/Cu(100)]. In the case of CH2=CHCOOH on O/Cu(100), CH2=CHCOO is the surface intermediate detected between 110 K and 400 K. CH2=CHCOO is adsorbed vertically and can change adsorption sites at a higher temperature. The propenoate (acrylate) decomposes at higher temperatures (>500 K), with formation of >C=C=O (ketenylidene) surface species and gaseous products. On Cu(100), CH2=CHCOOH is adsorbed in dimer form and can dissociate to generate CH2=CHCOO and CH3CHCOO intermediates on the surface. The CH3CHCOO continuously recombines with the H from deprotonation of CH2=CHCOOH, resulting in the formation CH3CH2COO. The co-existing CH2=CHCOO and CH3CH2COO further decompose at ∼550 K to evolve reaction products, but without >C=C=O being detected. On O/Cu(100), CH3CHFCOOH readily deprotonates to form CH3CHFCOO at 120 K. This intermediate reacts on the surface at ∼460 K to evolve gaseous products, also producing CH2=CHCOO. In the case of Cu(100), deprotonation of CH3CHFCOOH occurs at ∼250 K, forming CH3CHFCOO. Without oxygen on the surface, this intermediate decomposes into HF and CH2=CHCOO at ∼455 K.

A mesoporous biomaterial for biomimetic crystallization in dentinal tubules without impairing the bonding of a self-etch resin to dentin.

BACKGROUND/PURPOSE: CaCO3@mesoporous silica reacted with phosphoric acid (denoted as CCMS-HP) enables the growth of calcium phosphate crystals in dentinal tubules. This study tested whether CCMS-HP could be used to form a biomimetic barrier on the exposed dentin for prevention of dentin sensitivity without impairing the bonding of Single Bond Universal (SBU) self-etch adhesive to the dentin. METHODS: Twenty-four dentin disks were prepared and divided into three groups: (1) SBU group (n = 8), in which SBU self-etch adhesive was bonded to the dentin disk directly; (2) CCMS-HP group (n = 8), in which CCMS-HP was applied onto the dentin surface; and (3) CCMS-HP/SBU group (n = 8), in which the dentin surface was first treated with CCMS-HP and then boned by SBU. The permeation depth of crystals into the dentinal tubules was examined and measured with a scanning electron microscope. The shear bonding strength of SBU and CCMS-HP/SBU to dentin was also measured. RESULTS: The mean crystal permeation depth was 35.8 ± 6.9 µm for the CCMS-HP/SBU group and 33.6 ± 12.2 µm for the CCMS-HP group; no significant difference was found between the two groups. Moreover, the mean shear bonding strength was 22.7 ± 6.7 MPa for the CCMS-HP/SBU group and 23.3 ± 7.0 MPa for the SBU group. There was also no significant difference between the two groups. CONCLUSION: CCMS-HP can be used to form a biomimetic barrier for prevention of dentin sensitivity because it neither impedes the bonding of SBU to dentin nor impairs the shear bonding strength between the SBU and dentin.

Synthesis of mesoporous silica nanoparticles.

Good control of the morphology, particle size, uniformity and dispersity of mesoporous silica nanoparticles (MSNs) is of increasing importance to their use in catalyst, adsorption, polymer filler, optical devices, bio-imaging, drug delivery, and biomedical applications. This review discusses different synthesis methodologies to prepare well-dispersed MSNs and hollow silica nanoparticles (HSNs) with tunable dimensions ranging from a few to hundreds of nanometers of different mesostructures. The methods include fast self-assembly, soft and hard templating, a modified Stöber method, dissolving-reconstruction and modified aerogel approaches. In practical applications, the MSNs prepared by these methods demonstrate good potential for use in high-performance catalysis, antireflection coating, transparent polymer-MSNs nanocomposites, drug-release and theranostic systems.

Effects of surface treatments of bioactive tricalcium silicate-based restorative material on the bond strength to resin composite.

OBJECTIVES: This study aimed to enhance the bond strength between Biodentine™ (BD), a bioactive tricalcium silicate (C3S) based material, and resin composite through various surface treatments. METHODOLOGY: BD samples were immersed in either double distilled water or Hank's Balanced Salt Solution and analyzed using X-ray Diffraction (XRD). Shear bond strength (SBS) evaluations of BD were performed using Prime & Bond™ NT (PNT), Single Bond Universal (SBU), Xeno V (Xeno), and glass ionomer cement (GIC) following various etching durations (0 s/ 15 s/ 30 s/ 60 s with 37.5% phosphoric acid). Two primers, RelyX™ Ceramic Primer (RCP) and Monobond ™ Plus (MBP), were chosen to prime BD for SBS enhancement. Fractography and bonding interfaces were examined with energy dispersive X-ray spectroscopy (EDS)/ scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). RESULTS: XRD confirmed BD's main compositions as C3S, Ca(OH)2, CaCO3 and ZrO2 after 14 days crystal maturation. Etched BD did not improve SBS. GIC exhibited the lowest SBS (p < 0.05) among all adhesives, regardless of the etching mode (all < 1 MPa). The highest SBS (17.5 ± 3.6 MPa, p < 0.05) was achieved when BD primed with MBP followed by SBU application. FTIR and EDS showed γ-MPTS and10-MDP within the MBP primer interacted with C3S and ZrO2 of BD, achieving enhanced SBS. Most specimens exhibited mixed or cohesive failure modes. Significance BD's subpar mechanical properties and texture may contribute to its poor adhesion to resin composite. Pretreating BD with MBP primer, followed by SBU adhesive is recommended for improving bond strength.

Synthesis of Mesoporous Eu3+-Doped Zinc/Silicate Phosphors for Highly Selective and Sensitive Detection of Sulfide Ions.

A mesoporous Eu3+-doped zinc/silicate phosphor with a large surface area (>100 m2g-1) and amorphous structure was prepared in an aqueous solution without using any organic template. The residual concentration of the Zn2+ ion in the filtrate is lower than the standard of effluent 3.5 ppm under a pH 8-11 preparation condition. When a sulfide ion (S2-) is present in aqueous solution, the phosphor can react with the sulfide ion to transform from the amorphous structure to the crystalline ZnS, which causes structural transformation and a subsequent decrease in luminescent intensity. This distinct phosphor with a high surface area and amorphous structure can be applied through the structure transformation mechanism for highly selective and sensitive detection of the sulfide ions at low concentrations. In addition, the luminescent efficiency was obtained from adjustments in the pH value, calcination temperature, and Eu3+ ion concentration. The quenching efficiency, the limit of detection (CLOD), S2- ion selectivity, and phosphor regeneration ability were systematically explored in sulfide ion detection tests. Due to the novel S2- ion-induced structural transformation, we found that the amorphous Eu3+-doped zinc/silicate phosphors demonstrate a CLOD sensitivity as low as 1.8 × 10-7 M and a high Stern-Volmer constant (KSV) of 3.1 × 104 M-1. Furthermore, the phosphors were easily regenerated through simple calcination at 500 °C and showed a KSV value of 1.4 × 104 M-1. Overall, the Eu3+-doped zinc/silicates showed many advantageous properties for detecting sulfide ions, including low toxicity, green synthesis, good selectivity, high sensitivity, and good renewability.

Optimizing the Micro/Mesoporous Structure of Hierarchical Porous Carbon Synthesized from Petroleum Pitch Using the Solvent-Free Method for Ultra-Fast Capacitive Deionization.

In this work, a solvent-free ZnO-template method is used to synthesize hierarchical porous carbons (denoted as HPC-X; X = 1, 1.5, 2, and 4 g of ZnO) via the pyrolysis of petroleum industrial-residual pitch with ZnO. The proposed method allows precise control of the micro/meso/macroporous structure of the HPC by adjusting the amount of ZnO. The results show that the average pore size of HPCs prominently increases from 2.4 to 3.7 nm with the increase in the ZnO/pitch ratio. In addition, it is shown that HPCs have a high surface area between 1141 and 1469 m2 g-1, a wide-range pore size distribution (micro-, meso-, and macropores), and a tap density ranging from 0.2 to 0.57 g cm-3. The capacitive deionization performances of HPCs for sodium and chloride ions are investigated. The results show that HPC-2 exhibits the highest electrosorption capacity of 9.94 mg g-1 within 10.0 min and a maximum electrosorption capacity of 10.62 mg g-1 at 1.2 V in a 5.0 mM NaCl solution. Hence, HPC-2 is a highly promising candidate as an electrode material for rapid deionization.

Electrospun Benzimidazole-Based Polyimide Membrane for Supercapacitor Applications.

A benzimidazole-containing diamine monomer was prepared via a simple one-step synthesis process. A two-step procedure involving polycondensation in the presence of aromatic dianhydrides (4,4'-oxydiphthalic anhydride, ODPA) followed by thermal imidization was then performed to prepare a benzimidazole-based polyimide (BI-PI). BI-PI membranes were fabricated using an electrospinning technique and were hot pressed for 30 min at 200 °C under a pressure of 50 kgf /cm2. Finally, the hot-pressed membranes were assembled into supercapacitors, utilizing high-porosity-activated water chestnut shell biochar as the active material. The TGA results showed that the BI-PI polymer produced in the two-step synthesis process had a high thermal stability (Td5% = 527 °C). Moreover, the hot-press process reduced the pore size in the BI-PI membrane and improved the pore-size uniformity. The hot-press procedure additionally improved the mechanical properties of the BI-PI membrane, resulting in a high tensile modulus of 783 MPa and a tensile strength of 34.8 MPa. The cyclic voltammetry test results showed that the membrane had a specific capacitance of 121 F/g and a capacitance retention of 77%. By contrast, a commercial cellulose separator showed a specific capacitance value of 107 F/g and a capacitance retention of 49% under the same scanning conditions. Finally, the membrane showed both a small equivalent series resistance (Rs) and a small interfacial resistance (Rct). Overall, the results showed that the BI-PI membrane has significant potential as a separator for high-performance supercapacitor applications.

Sustainable, biocompatible, and mass-producible superwetting water caltrop shell biochars for emulsion separations.

The separation of oily wastewater, specifically emulsions, is a crucial global issue. Possible strategies for the efficient separation of emulsified oil/water mixtures through sustainable and environmentally friendly materials have recently drawn considerable attention. In our study, we prepared superwetting water caltrop shell biochar (WCSB) via a top-lit-updraft carbonization procedure. The as-prepared WCSB was characterized by superhydrophilicity, underwater superoleophobicity, underoil superhydrophilicity, and underoil water adsorption ability. Because of its superwetting properties, WCSB was used for the separation of both surfactant-stabilized oil-in-water emulsions (SOIWEs) and surfactant-stabilized water-in-oil emulsions (SWIOEs) with very high fluxes (up to 74,700 and 241,000 L m-2 h-1 bar-1 for SOIWE and SWIOE, respectively). The separation performances were excellent, with oil contents in all SOIWE filtrates lower than 10 ppm and oil purities in all SWIOE filtrates higher than 99.99 wt%. Moreover, WCSB was applied to separate dye-spiked emulsions. Due to their high emulsion separation ability, sustainability, good biocompatibility, and ease of mass production, the as-prepared WCSBs have notable potential for utilitarian applications.

Effects of morphology and pore size of mesoporous silicas on the efficiency of an immobilized enzyme.

An investigation is performed into the efficiency of the Streptomyces griseus HUT 6037 enzyme immobilized in three different mesoporous silicas, namely mesoporous silica film, mesocellular foam, and rod-like SBA-15. It is shown that for all three supports, the pH value changes the surface charge and charge density and hence determines the maximum loading capacity of the enzyme. The products of the enzyme hydrolytic reaction are analyzed by 1H-NMR. The results show that among the three silica supports, the mesoporous silica film (with a channel length in the range of 60-100 nm) maximizes the accessibility of the immobilized enzyme. The loading capacity of the enzyme is up to 95% at pH 7 and the activity of the immobilized enzyme is maintained for more than 15 days when using a silica film support. The order of the activity of the enzyme immobilized in different mesoporous silica supports is: mesoporous silica film > mesocellular foam > rod-like SBA-15. Furthermore, the immobilized enzyme can be easily separated from the reaction solution via simple filtration or centrifugation methods and re-used for hydrolytic reaction as required.

Green synthesis of nitrogen-doped multiporous carbons for oxygen reduction reaction using water-caltrop shells and eggshell waste.

A green synthesis method is proposed for the preparation of nitrogen-doped multiporous carbons (denoted as N-MPCs) from water-caltrop shell (WCS) using eggshell waste as both a nitrogen-dopant and an activating agent. It is shown that the surface area, porosity, yield and nitrogen content of the as-prepared N-MPCs can be easily controlled by adjusting the activation temperature. Moreover, in oxygen reduction reaction (ORR) tests performed in O2-saturated 0.1 M KOH(aq) electrolyte containing 1.0 M methanol, the N-MPC catalysts show a high ORR stability and good resistance to methanol corrosion. In addition, as a cathode material in Al-air battery tests, the N-MPCs achieve a power density of 16 mW g-1 in a saturated NaCl(aq) electrolyte. Overall, the results show that the N-MPCs have a promising potential as a green and sustainable material for ORR catalysis applications.

Correction: Green synthesis of nitrogen-doped multiporous carbons for oxygen reduction reaction using water-caltrop shells and eggshell waste.

[This corrects the article DOI: 10.1039/D1RA02100A.].

Reaction pathways of 2-iodoacetic acid on Cu(100): coverage-dependent competition between C-I bond scission and COOH deprotonation and identification of surface intermediates.

The chemistry of 2-iodoacetic acid on Cu(100) has been studied by a combination of reflection-absorption infrared spectroscopy (RAIRS), X-ray photoelectron spectroscopy (XPS), temperature-programmed reaction/desorption (TPR/D), and theoretical calculations based on density functional theory for the optimized intermediate structures. In the thermal decomposition of ICH(2)COOH on Cu(100) with a coverage less than a half monolayer, three surface intermediates, CH(2)COO, CH(3)COO, and CCOH, are generated and characterized spectroscopically. Based on their different thermal stabilities, the reaction pathways of ICH(2)COOH on Cu(100) at temperatures higher than 230 K are established to be ICH(2)COOH --> CH(2)COO + H + I, CH(2)COO + H --> CH(3)COO, and CH(3)COO --> CCOH. Theoretical calculations suggest that the surface CH(2)COO has the skeletal plane, with delocalized pi electrons, approximately parallel to the surface. The calculated Mulliken charges agree with the detected binding energies for the two carbon atoms in CH(2)COO on Cu(100). The CCOH derived from CH(3)COO decomposition has a CC stretching frequency at 2025 cm(-1), reflecting its triple-bond character which is consistent with the calculated CCOH structure on Cu(100). Theoretically, CCOH at the bridge and hollow sites has a similar stability and is adsorbed with the molecular axis approximately perpendicular to the surface. The TPR/D study has shown the evolution of the products of H(2), CH(4), H(2)O, CO, CO(2), CH(2)CO, and CH(3)COOH from CH(3)COO decomposition between 500 and 600 K and the formation of H(2) and CO from CCOH between 600 and 700 K. However, at a coverage near one monolayer, the major species formed at 230 and 320 K are proposed to be ICH(2)COO and CH(3)COO. CH(3)COO becomes the only species present on the surface at 400 K. That is, there are two reaction pathways of ICH(2)COOH --> ICH(2)COO + H and ICH(2)COO + H --> CH(3)COO + I (possibly via CH(2)COO), which are different from those observed at lower coverages. Because the C-I bond dissociation of iodoethane on copper single crystal surfaces occurs at approximately 120 K and that the deprotonation of CH(3)COOH on Cu(100) occurs at approximately 220 K, the preferential COOH dehydrogenation of monolayer ICH(2)COOH is an interesting result, possibly due to electronic and/or steric effects.

Electro-microchip DNA-biosensor for bacteria detection.

This paper presents a bacteria biosensor based on DNA hybridization detection with an electro-microchip transducer. Acinetobacter baumannii was chosen as DNA sample source, because the occurrence of bacteremia caused by Acinetobacter baumannii is high in hospitals worldwide. Our strategy is based on DNA hybridization of PCR amplified bacteria DNA with biotin labelled primers and detection enhancement using gold-streptavidin nanoparticles and Ag(+)-hydroquinone solution. Gold nanoparticles catalyze silver ions reduction by hydroquinone. The gradually precipitated silver metal between the two electrodes of the electro-microchip allows electrons to pass. The detection limit for Acinetobacter baumannii genomic DNA sample is 0.825 ng mL(-1) (1.2 fM). Probe specificity was investigated by screening various species of bacteria, various strains of a single species and various species of a single genus. The proposed DNA hybridization method is easy, convenient, and rapid. Moreover, it has potential applications in detection of bacteria causing infections and clinical diagnosis.

Preparation of carboxylated magnetic particles for the efficient immobilization of C-terminally lysine-tagged Bacillus stearothermophilus aminopeptidase II.

This article reports the synthesis and use of surface-modified iron oxide particles for the simultaneous purification and immobilization of Bacillus stearothermophilus aminopeptidase II (BsAPII) tagged C-terminally with either tri- or nona-lysines (BsAPII-Lys(3/9)). The carboxylated magnetic particles were prepared by the simple co-precipitation of Fe(3+)/Fe(2+) in aqueous medium and then subsequently modified with adipic acid. Transmission electron microscopy (TEM) micrographs showed that the carboxylated magnetic particles remained discrete and had no significant change in size after binding BsAPIIs. Wild-type enzyme and BsAPII-Lys(3) could be purified to near homogeneity by the carboxylated magnetic particles, but it was not easy to elute the adsorbed BsAPII-Lys(9) from the matrix. Free BsAPII, BsAPII-Lys(3), and BsAPII-Lys(9) were active in the temperature range 50-70 degrees C and all had an optimum of 50 degrees C, whereas the optimum temperature and thermal stability of BsAPII-Lys(3) and BsAPII-Lys(9) were improved as a result of immobilization. The immobilized BsAPII-Lys(9) could be recycled ten times without a significant loss of the enzyme activity and had a better stability during storage than BsAPII. Owing to its high efficiency and cost-effectiveness, this magnetic adsorbent may be used as a novel purification-immobilization system for the positively charged enzymes.

Synthesis of Multiporous Carbons from the Water Caltrop Shell for High-Performance Supercapacitors.

In this study, an economic, sustainable, and green synthesis method of multiporous carbons from agricultural waste, water caltrop shell (denoted as WCS), was presented. To prepare the WCS biochar, the dried WCS was first carbonized to a microporous carbon with a surface area of around 230 m2 g-1 by using a top-lit-updraft method. Then, the microporous WCS biochar was directly mixed with an appropriate amount of ZnO nanoparticles and KOH as activating agents via a solvent-free physical blending route. After further activation at 900 °C, the resulted carbons possess both micropores and mesopores that were named as WCS multiporous carbons. The carbon yield of the prepared WCS multiporous carbons with high surface area in the range of 1175-1537 m2 g-1 is up to 50%. Furthermore, the micropore/mesopore surface area ratio can be simply tuned by controlling the ZnO content. For supercapacitor applications, the as-prepared WCS multiporous carbon electrodes showed high specific capacitance (128 F g-1 at 5 mV s-1) with a good retention rate at 500 mV s-1 scan rate (>60% compared to the capacitance at 5 mV s-1) and low Ohmic resistance in a 1.0 M LiClO4/PC electrolyte. In addition to the ZnO nanoparticles, CaCO3 nanoparticles with low environmental impact were also used to prepare the WCS multiporous carbons. The assembled supercapacitors also demonstrate high specific capacitance (102 F g-1 at 5 mV s-1) and good retention rate (∼70%).

Application of metallic nanoparticle-biochars with ionic liquids for thermal transfer fluids.

Ionic liquids (ILs (1-butyl-3-methylimidazolium chloride ([C4mim][Cl]) and 1-butyl-3-methylimidazolium tetrafluoroborate ([C4mim][BF4]))) were used as heat transfer fluids for solar thermal collectors. The additive of ILs was biochar containing copper and silver nanoparticles (Cu-Ag/biochar) to improve the adsorption of solar irradiation and thermal conductivities. After impregnation and reduction processes, nanoparticles such as Cu, CuO, Cu(OH)2, Ag, and Ag2O were found in the biochar by X-ray powder diffraction (XRD) spectroscopy. With adding 2% Cu-Ag/biochar into the ILs, the thermal conductivities of [C4mim][Cl] and [C4mim][BF4] containing 10% Cu-1% Ag/biochar were individually increased 9.2 and 6.6 times compared to the base ILs due to the high graphitization of biochar and metallic nanoparticles. The 1H NMR (nuclear magnetic resonance) features of the imidazole ring and methyl group in the ILs were highly disturbed due to the formation of weak or strong hydrogen bonds between the cations in ILs and Cu-Ag/biochar. The high hydrogen bond acceptance of anions in ILs also affected the thermal properties. The thermal properties of the metals/biochar [C4mim][Cl] were better than those of metals/biochar [C4mim][BF4] due to high hydrogen bond acceptance of [Cl]-. The strong hydrogen bonds between the Cu-Ag/biochar and the cations and anions in ILs result in thermal properties of heat transfer fluids. Under simulated sunlight, the temperatures of [C4mim][Cl] and [C4mim][BF4] containing 10% Cu-1% Ag/biochar rose from 304 to 345 and 340 K within 24 min, respectively. A novel heat transfer fluid was developed for high adsorption of irradiation, high thermal conductivities, and speedy transfer of heat.