RSC Advances

Wang, Li; Zhang, Haoran; Zhou, Xiaohua; Liu, Yingliang; Lei, Bingfu

doi: 10.1039/c6ra20380apmid: N/A

In this work, we present a rapid, selective and highly sensitive sensor for the detection of oxygen based on ratiometric fluorescent luminescent carbon dots (CDs) grafted CaSiO3:Eu3+. Highly monodispersed porous silica microspheres are obtained with particle sizes in the range between 120 and 180 nm, providing a key precursor to prepare the CaSiO3:Eu3+ phosphor. The fluorescence of CDs grafted CaSiO3:Eu3+ could be quenched by oxygen and the red emission of Eu3+ (613 nm and 703 nm) and the blue emission of the CDs (454 nm) were effectively reduced as the concentration of oxygen increased. The CaSiO3:Eu3+ phosphor shows little effect on oxygen, while CDs grafted CaSiO3:Eu3+ shows good oxygen sensing properties, the response time is determined to be about 4–7 s and the recovery time is 18–29 s. The obtained CDs grafted CaSiO3:Eu3+ sample appears to be a promising sensing material for environmental detection applications and would also find applications in catalysis, electrodes, or related fields.

Yin, Tiantian; Zhang, Xinying; Liu, Xiaoyan; Li, Beibei; Wang, Chaoqun

doi: 10.1039/c6ra22950fpmid: N/A

Cellulose-based aerogels (CBAs) were prepared based on Eichhornia crassipes as a raw material and a paper wet-strengthening agent as a cross-linker via a green and simple process. The hydrophobic CBAs had excellent properties, including low density (<0.0055 g cm−3), high porosity (>99.6%), excellent oil/solvent sorption capacities (58.06–101.14 g g−1), superhydrophobicity (water contact angle as high as 154.8°), and superior elasticity. Moreover, the absorbed oil could be quickly recovered by squeezing, and the oil sorption capacity was still as high as 75% of the original sorption capacity after 16 cycles. This work provides a facile and cost-effective method to fabricate a novel superabsorbent from waste biomass materials, which is very promising in terms of using waste to deal with oil pollution.

Zhong, Shi-Long; Zhou, Zheng-Yong; Zhang, Kai; Shi, Yu-Dong; Chen, Yi-Fu; Chen, Xu-Dong; Zeng, Jian-Bing; Wang, Ming

doi: 10.1039/c6ra24046apmid: N/A

Fabrication of thermally conductive networks in polymer matrices is thought to be an efficient way to improve the thermal conductivity of polymer composites. Here we show a new approach to form thermally conductive networks in isotactic polypropylene (iPP)/hexagonal boron nitride (h-BN) composites via “bridge effect” of multi-wall carbon nanotubes (MWCNTs) or graphene nanoplatelets (GNPs). The isolated h-BN particles can be connected by MWCNTs or GNPs to form three-dimensional thermally conductive networks. It is found that the thermal conductivity of the iPP/h-BN composites is obviously enhanced but maintaining the electrical insulation by adding small amount of MWCNTs or GNPs. Because of the large content area of GNPs, the “bridge effect” of GNPs is more obvious than that of MWCNTs. The thermal conductivity of the iPP/h-BN composites with 10 wt% and 30 wt% h-BN particles show 14% and 23% enhancement by incorporation of 5.0 phr MWCNTs, respectively. Meanwhile, the thermal conductivity of the iPP/h-BN composites with 10 wt% and 30 wt% h-BN particles are enhanced by 59% and 70% when adding 5.0 phr GNPs, respectively. The electrical conductivities of the iPP/h-BN composites with MWCNTs and GNPs were maintained below 2.5 × 10−13 and 2.6 × 10−15 S cm−1, respectively.

Xu, Na; Liang, Jiaqi; Qian, Tao; Yang, Tingzhou; Yan, Chenglin

doi: 10.1039/c6ra24394kpmid: N/A

2D hybrid sheets of V2O5 and reduced graphene oxide (rGO/V2O5) have been synthesized using a hydrothermal method. With the addition of tiny amount of rGO content (6.25%), the proper conductivity and accessibility of hybrid nanosheets for lithium ion migration are obviously promoted. Compared with the bare V2O5 sheets, the rGO/V2O5 hybrid sheets exhibited enhanced electrochemical performance in terms of improved cycling stability (nearly 81.5% capacity retention after 200 cycles), high reversible capacity of 249 mA h g−1 at a current density of 100 mA g−1 and good rate capability for the half cell. Significantly, a Li-metal-free full battery is assembled successfully, with rGO/V2O5 hybrid sheets and lithiated graphite for cathodes and anodes, respectively. This full Li-ion battery exhibits a superior specific capacity of 213 mA h g−1 at a current density of 100 mA g−1 and a high specific energy density of 106.5 W h kg−1 as a result. The good electrochemical performance suggests that this unique 2D hybrid material could be a promising candidate as a cathode material for lithium-ion batteries in the near future.

Zhang, Yi; Chi, Yuan; Liu, Shuyang; Xing, Wanli; Wang, Lulu; Song, Yongchen

doi: 10.1039/c6ra16198gpmid: N/A

The adsorption/desorption of CO2/CH4 mixtures with three different volume fractions was investigated at 294 K, 311 K, 333 K, and 353 K with pressures of up to 70 bar on anthracite from China using a high-pressure volumetric analyzer (HPVA II-200). For the mixtures, the total excess adsorbed amount decreased as the temperature rose. In addition, it displayed an upward tendency with an increase in the CO2 fraction in the feed gas. The excess adsorbed amounts of the component gases were calculated on the basis of the composition of the gas phase measured by gas chromatography. For a mixture with a CO2 fraction of 50%, relatively good adsorptivity for CO2 was displayed at low pressures (<30 bar), whereas better adsorptivity for CH4 was displayed at high pressures. When the CO2 fraction in the feed gas increased from 20% to 50%, the excess adsorbed amount of CO2 increased dramatically, whereas the excess adsorbed amount of CH4 decreased slightly (6.3%). When the CO2 fraction increased from 50% to 80%, the excess adsorbed amount of CO2 increased substantially, whereas the excess adsorbed amount of CH4 decreased drastically (42.4%). On the basis of the experimental data, the total excess adsorbed amount can be well simulated by the Ono–Kondo (OK) lattice thermodynamic model with an average deviation of 6.4%. Moreover, the excess adsorbed amounts of the individual components have also been predicted using the OK model.

Zhang, Jinrui; Li, Xiaoyan; Wang, Xia; Qiu, Biwei; Li, Zhoujing; Ding, Jie

doi: 10.1039/c6ra20520hpmid: N/A

A vertically aligned carbon nanotube (CNT)/polyaniline (PANi) composite membrane was prepared by a simple filtration and electrical synergy method. Considering the high alternating electric field and strong shear forces during suction, vertically aligned single-walled nanotubes (SWNTs) were found in the SWNT/PANi composite membrane. Scanning electron microscopy and polarised Raman scattering demonstrated that the degree of alignment of the SWNTs improved with increasing electric voltage. Nanoindentation technology indicated that the modulus and hardness of the SWNT/PANi composite membrane increased in the vertically aligned CNTs. Owing to the special photo-thermal property of the PANi nanofibres, a SWNT/PANi composite film with an improved crosslinking structure and strong π–π interactions between PANi and SWNTs was obtained by intensity flash irradiation. The surface density, water contact angle and thermal stability of the composite film increased after flash welding. Nanoindentation technology indicated that the SWNT/PANi composite film significantly increased in modulus and hardness after flash welding. The SWNT/PANi film fabricated by filtration and electrical synergy method also demonstrated an improved specific capacitance of 146.0 F g−1 in 6 M KOH at 0.5 A g−1 after flash welding while maintaining good cycling stability. The prepared SWNT/PANi composite film is suitable for portable and wearable electronic applications.

Wu, Xinhu; Zhao, Gaiqing; Zhao, Qin; Gong, Kuiliang; Wang, Xiaobo; Liu, Weimin; Liu, Weisheng

doi: 10.1039/c6ra22863apmid: N/A

We report for the first time that nanosized MoS2 on graphene (MoS2/Gr) was used as an additive in perfluoropolyether (PFPE) base oil. The nanocomposite can not only form a stable dispersion in PFPE for two weeks but also dramatically improve the friction-reduction and antiwear properties of the base oil for steel/steel contact under high vacuum.

Ma, Li; Du, Peng; Yang, Jin; Liu, Ying-Ying; Liu, Xiao-Li; Ma, Jian-Fang

doi: 10.1039/c6ra18817fpmid: N/A

Two heterotrimetallic organic frameworks [(CH3)2NH2][Cd2Na(Fe-L)2(H2O)6]·4DMF·4H2O (1) and [ZnNa(Fe-L)(H2O)]·2DMF·2H2O (2), have been synthesized via the reaction of a novel tetracarboxyl-functionalized 1,2-ethanediamino-N,N′-bis(3-tertiarybutyl-5-((3,5-carboxybenzyl)oxy)salicylidene) (H6L) Schiff base ligand. In 1 and 2, the internal [N2O2] pockets of L6− anions are embedded by Fe(iii) ions, while the external carboxylate groups are ligated by Zn(ii)/Cd(ii) and Na(i) ions. Both frameworks display fascinating 3D frameworks. The photodegradation properties of 1 and 2 towards 4-chlorophenol (4-CP) and 2,4-dichlorophenol (2,4-DCP) under visible light have been systematically investigated. Their magnetic behaviors have also been studied.

Das, Sudhanshu; Adhikary, Jaydeep; Chakraborty, Prateeti; Chakraborty, Tonmoy; Das, Debasis

doi: 10.1039/c6ra05478apmid: N/A

Addition of 1,3-propane diamine to 2,6-diformyl-4-tert-butyl phenol in ethanol produces a site-selective imination product N,N′-propylenebis(3-formyl-5-tert-butylsalicylaldimine), an acyclic side-off compartmental ligand (H2L). In the presence of zinc nitrate the ligand goes on hydrolysis in 50 : 50 water–acetonitrile medium and forms a partially hydrolyzed ligand (H2L′) which slowly metallates to generate a macrocyclic dinuclear zinc(ii) complex (1), as characterized by single crystal X-ray analyses. The formation of H2L′ is believed to occur through the cleavage of an imine bond of the acyclic compartmental ligand (H2L) in the presence of zinc nitrate which acts as a Lewis acid. The formation of H2L′ has been monitored by means of 1H NMR and further confirmed by HRMS spectroscopic studies. The interactions of H2L with nickel(ii) and copper(ii) nitrate produce dinuclear complexes 2 and 3 (reported in Inorg. Chem. Commun. 2012, 15, 266–268) respectively, which are formed with unchanged ligand. Various spectroscopic techniques have been used to further characterize the complexes. H2L hardly exhibits yellowish green fluorescence emission at 523 nm when excited at 437 nm in 1 : 1 water–acetonitrile. Upon addition of Zn2+, a new fluorescence emission band at 481 nm appears, the intensity of which slowly enhances. Thus, the ligand H2L is a ratiometric fluorescence chemodosimeter for the selective detection of Zn2+ ions. On addition of CaII, MgII, NaI and KI in the same concentrations as that of Zn2+, the emission band at 523 nm is slightly enhanced, whereas the addition of paramagnetic metal cations like CuII, FeII, NiII, CoII, and MnII resulted in quenching of fluorescence. The quenching effect is also observed in the presence of CdII, a d10 metal cation exhibiting similar coordination properties to ZnII. The ZnII ion selectivity has also been studied in the presence of other biologically relevant metal ions in 50 : 50 water–acetonitrile.

Li, Guo-An; Li, Wei-Chin; Chang, Wei-Chung; Tuan, Hsing-Yu

doi: 10.1039/c6ra20171gpmid: N/A

Germanium oxide (GeO2) nanoparticles were synthesized with a nearly 100% production yield in a nonionic reverse micelle system at ambient temperature. The procedure is a facile and energy saving strategy for producing germanium oxide nanoparticles with ultra large throughput. As-prepared GeO2 nanoparticles can be directly used as anode materials without any post-treatment or other supplementary additives for lithium ion batteries. GeO2-anodes exhibited good electrochemical performance in terms of both gravimetric and volumetric capacity. The GeO2 anodes have a reversible capacity of approximately 1050 mA h g−1 at a rate of 0.1C, close to its theoretical capacity (1100 mA h g−1), and good rate capability without severe capacity decade. The volumetric capacity of the GeO2 anodes reaches 660 mA h cm−3, which is higher than the performance of commercial graphite anode (370–500 mA h cm−3). Coin type and pouch type full cells assembled for electronic devices applications were also demonstrated. A single battery is shown to power LED array over 120 bulbs with a driving current of 650 mA. Based on the above, the micelle process of GeO2 nanoparticle synthesis provides a possible solution to high-capacity nanoparticles' scalable manufacturing for lithium ion battery applications.