Small
·
2018
·Vol. 14
·期 19
·1800367
·
IF 9.598
Hui Li,Si-Min Xu,Hong Yan,Lan Yang,Sailong Xu
Exploring highly efficient and stable oxygen evolution reaction (OER) electrocatalysts such as transition-metal phosphides (TMPs) is critical to advancing renewable hydrogen fuel. TMP nanostructures typically involving binary or ternary TMPs tuned by cation or anion doping are suggested to be promising low-cost and durable OER catalysts. Herein, the preparation of CoP/CoP 2 composite nanoparticles encapsulated within N,P-doped carbon nanotubes (CoP/CoP 2 @NPCNTs) is demonstrated as a synergistic electrocatalyst for OER via the calcination of a CoAl-layered double hydroxide/melamine mixture and subsequent phosphorization. Facile visualization by scanning electron microscopy in conjunction with electron backscatter diffraction demonstrates the encapsulation of the CoP/CoP 2 nanoparticles within the N,P-codoped CNTs. Electrocatalytic evaluation shows that the composite electrode requires a low overpotential of 300 mV for the OER at 10 mA cm −2 in a 1.0 m KOH solution and, in particular, exhibits an excellent long-term durability of ≈100 h, which is superior to that of the state-of-the-art RuO 2 electrocatalyst. Density functional theory calculations reveal that the synergistic effect of CoP and CoP 2 can enhance the electrocatalytic performance. In addition, molecular dynamics simulations demonstrate that the generated O 2 molecules can readily diffuse out of the CNTs. Both the effects give rise to the observed OER enhancement.
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CHEMICAL ENGINEERING JOURNAL
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2018
·
IF 6.735
Yuan Gao,Kunmei Su,Zhenhuan Li,Bowen Cheng
Using organosilicon to crosslink and intercalate GO sheets, we made a hybrid GO layer on the surface of poly(p-phenylene sulfide) (PPS) microporous membrane support. A large number of oxygen-containing groups were introduced into the interlayer of GO layer, forming hydrophilic channels, more free interlayer space and nano-channels, which greatly enhanced the permeation and transmission of hydrophilic solvent. Furthermore, the introduced organosilicon species could improve the stability of PPS-GO@PB hybrid membranes. Water and ethanol were used as models to test the permeability of hybrid membranes, the results showed that the water and ethanol fluxes of GO@PB hybrid PPS membranes increased significantly. Especially, the water and ethanol fluxes of PPS-0.1GO@2.5PB membrane achieved 34.3 and 12.8 LMH under the pressure of 0.5 MPa. Four kinds of dyes were used as model pollutants to test the separation efficiency of the modified membrane, showing the high rejection of 99.2% (MB), 93.8% (MEB), 90.2% (BS) and 92.4% (RB), respectively. In the test of operation stability and solvent resistance, PPS-0.1GO@2.5PB membrane showed excellent stability and solvent resistance. These findings suggest that the as-prepared GO@PB hybrid PPS membrane will be great potential for utilization in the field of separation and purification of organic solvents and small molecules.
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APPLIED SURFACE SCIENCE
·
2018
·
IF 4.439
Jia Guo,Dongling Wu,Tao Wang,Yan Ma
P-doped hierarchical porous carbon aerogels are prepared by carbonizing the phloroglucin-formaldehyde resins in the presence of ZnCl 2 and subsequently being activated by KOH. Phosphoric acid is simultaneously used as the polymerization catalyst and P-doped agent in the preparation procedure. Compared with un-doped sample, P-doped carbon with hierarchical porous structure shows improved electrochemical performance. The prepared sample that activated at 800 °C exhibits good capacitance of 406.2 F g −1 in 6 M KOH at a scan rate of 5 mV s −1 . When the scan rate is 500 mV s −1 , the specific capacitance still reaches to 267.4 F g −1 , demonstrating good rate capability. When 60 mg of active materials is loaded, the mass specific capacitance of the prepared electrode reaches to 348.8 F g −1 at a scan rate of 5 mV s −1 , and the maximum area capacitance is 11.35 F cm −2 . The energy density of the prepared sample is as high as 16.97 Wh kg −1 at a power density of 200 W kg −1 and reaches to 8.52 Wh kg −1 at 2000 W kg −1 . Importantly, after 100,000 charging and discharging cycles, the specific capacitance of the prepared sample is no attenuated, indicating a long-term electrochemical stability.
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PROGRESS IN REACTION KINETICS AND MECHANISM
·
2018
·
IF 0.649
Mengzhi Yang,Meiling Wang
This study investigated the adsorption process of p-nitrophenol (p-NP) onto partially reduced graphene oxide (prGO) using both experiment and theoretical calculations. The maximum adsorption capacity of prGO at pH 6.0 and 293 K for p-NP was 29.94 mg g−1 which was significantly higher than previously reported using a metal-doped reduced graphene oxide composite. Systematic, comparative theoretical calculations were used to investigate the adsorption mechanism of p-NP onto graphene oxide, prGO and graphene nanosheet (GN). Calculations revealed three types of adsorption site and indicated that the adsorption force and sites were significantly affected by the quantity and type of oxygen-containing functional groups on the GN. The adsorption affinity was mainly derived from hydrogen bonds and π-π stacking which was further demonstrated by FTIR analysis. Due to its excellent adsorption performance, good recyclability and easy separation, prGO can be a promising adsorbent for the efficient elimination of p-NP from wastewater in the future.
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MICROCHIMICA ACTA
·
2018
·Vol. 185
·期 12
·1-9
·
IF 5.705
Wang Yongping,Yue Qiaoli,Tao Lixia,Zhang Cong,Li Chen-Zhong
N/S/P-codoped carbon dots (CDs) are shown to be a viable fluorescent probe in a turn-off-on fluorometric assay for hydroquinone (HQ). The preparation of CDs was carried out using a one-step hydrothermal reaction starting with glyoxal and isocarbophos. The method is based on the formation of ground state complexes between CD and Fe(III) which leads to quenching of blue fluorescence (with excitation/emission peaks at 363/448 nm). On addition of HQ, it will be oxidized by Fe(III) upon which fluorescence recovers. This turn-off-on system can be utilized to quantify HQ. A linear relationship exists between fluorescence recovery and HQ concentration in range between 0.56 and 375 μM. The limit of detection is 0.16 μM. The assay was successfully applied to the determination of HQ in spiked water samples and developer samples.
Fluorometric determination of hydroquinone (with good selectivity over catechol and resorcinol) by using blue-emitting N/S/P-codoped carbon dots and the quenching effect of Fe(III).
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2018
·
IF 3.927
Junjian Zheng,Shaoping Xu,Zhichao Wu,Zhiwei Wang
Degradation of p -chloroaniline (PCA) was investigated using an electrochemical reactor with Ti/SnO 2 -Sb anode and cathodic electrochemical porous ceramic microfiltration (MF) membrane under galvanostatic control. Results showed that electrochemical degradation of PCA followed pseudo-first-order kinetics. At applied current 0.8 A and membrane flux 80 L m −2 h −1 , complete degradation of PCA (initial concentration of 0.6 mM) was achieved after 90-min electrolysis following adding 0.2 mM Fe 2+ at pH 3, with 75.1% of mineralization ratio and 46.7% of total nitrogen abatement. The production of OH via either anodic water oxidation or homogeneous and surface Fenton reaction was responsible for PCA degradation. The degradation pathways of PCA involving protonation, OH oxidation, and cathodic reduction were proposed by quantifying generated organic byproducts and inorganic nitrogen ions. Compared to cross-by operation, the cross-through operated EF system exhibited an enhanced oxidation power, leading to more efficient destruction of PCA and its toxic intermediate byproducts and improving electrical energy efficiency. This was ascribed to the increased ROS production and better contact of the contaminants with ROS present in the vicinity of membrane (cathode) surface induced by the enhanced mass transfer under membrane filtration. These results highlight the potential of the cross-through operated EF system to be used for the treatment of PCA-contaminated water and wastewater.
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CHEMOSPHERE
·
2018
·
IF 4.427
Xin Liu,Huahua Cai,Jing Zou,Zijun Pang,Baoling Yuan,Zhenming Zhou,Qingfeng Cheng
A sensitive spectrophotometric method (the N,N -diethyl- p -phenylenediamine (DPD) method) was established for the determination of trace permanganate concentration (0–10 μM) in water. The DPD method was based on the oxidative coloration reaction where permanganate could oxidize DPD to form the red colored DPD radical (DPD • + ) with a second-order rate constant of 2.96 × 10 4 M −1 s −1 at pH 6 (50 mM phosphate buffer). The generated DPD • + could be quantitatively measured at 551 nm using an UV–Vis spectrophotometer. There was a good linear relationship (R 2 = 0.999) between the absorbance of DPD • + and permanganate concentration. The DPD method was highly sensitive, and the absorbance of generated DPD • + at 551 nm was as high as 5.70 × 10 4 cm −1 per M (mol L −1 ) of permanganate. The reaction of permanganate with DPD in the pH range of 4.0–8.0 had a stoichiometric coefficient of 1:2.71. The residual absorbance of DPD •+ in ultrapure water and natural waters was fairly stable for 30 min. Limits of detection of the proposed DPD method in ultrapure water and natural waters were calculated to be as low as 0.010 μM and 0.017 μM, respectively. Moreover, trace permanganate concentrations of 0.04 and 0.10 μM were found in natural waters and wastewater by the proposed DPD method. Additionally, the DPD method could be applied to measure the second-order rate constants of the reaction of permanganate with phenol at pH 7.0 (28.2 M −1 s −1 ).
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Polymer Chemistry
·
2013
·Vol. 4
·期 10
·3020-3027
·
IF 5.231
Yangyi Sun,Yuyong Yin,Min Chen,Shuxue Zhou,Limin Wu
This paper presents a one-step procedure for the facile synthesis of monodisperse raspberry-like polymer colloidal particles by soap-free emulsion polymerization of styrene (S), acrylic acid (AA), and 3-(trimethoxysilyl)propyl methacrylate (MPS). In this method, when S, AA, and MPS are mixed with water and stirred at a certain temperature, raspberry-like P(S–MPS–AA) colloidal particles with uniform shapes and sizes could be obtained in a reliable manner. Both the core particles and the smaller corona particles of core surfaces were formed in situ. A mechanism of formation based on the second nucleation induced by MPS-enriched segments on the core surfaces is proposed.
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CRYSTENGCOMM
·
2012
·Vol. 15
·期 3
·560-569
·
IF 3.842
Zhifeng Jiang,Jimin Xie,Deli Jiang,Xiaojun Wei,Min Chen
Nickel nanoparticles with different sizes and morphologies were prepared with nickel chloride as the source of nickel and hydrazine hydrate as a reductant. Cetyltrimethyl ammonium bromide (CTAB), polyethylene glycol-10000 (PEG-10000), gelatin and their composites were used as modifiers in this research. The particles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM) and Fourier transform infrared (FTIR). The effect of using single modifiers and their composites was investigated. The results revealed that the kind of modifier used had a significant effect on the morphology and size of the Ni nanostructure. The possible formation mechanism of nickel nanoparticles was also investigated. All of the formed nickel nanoparticles showed excellent catalytic activity in the reduction of p-nitrophenol compared to the commercial RANEY® Ni. The catalytic activity of nickel particles prepared in the presence of composite modifiers was higher than nano nickel catalysts prepared in the presence of single modifiers. The magnetic property, possible catalytic mechanism and the possibility of reusability were also investigated.
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Soft Matter
·
2014
·Vol. 11
·期 2
·290-296
·
IF 4.151
Shu Peng,Kui Wang,Dong-Sheng Guo,Yu Liu
Supramolecular polymeric vesicles are constructed by the complexation of p-sulfonatocalix[4]arene and chitosan, where the multivalent electrostatic interactions between the anionic sulfonate tetramer and cationic polyammoniums served as the dominant driving force. The supra-amphiphilic assemblies are disassembled upon exposure to a pH stimulus since the partial deprotonation of chitosan accompanied by a pH increase. Adding a competitive guest can also disrupt the assembly, representing the host–guest inclusion response. Interestingly, an abnormal temperature-response is observed, possibly as a result of the temperature-directed fusion process.
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DALTON TRANSACTIONS
·
2014
·Vol. 43
·期 21
·7924-7929
·
IF 4.097
Linyi Zhou,Ming Wen,Qingsheng Wu,Dandan Wu
Magnetic FeNi@Ni nanocables were prepared as a superior recyclable catalyst towards the hydrogenation reduction of p-nitrophenol to p-aminophenol through a two-step tunable assembly process in a solvothermal system. The proposed fabrication mechanism was verified through characterization by SEM, TEM, XRD, XPS, and UV-Vis. The as-prepared FeNi@Ni nanocomposites are core–shell-structured nanocables with Ni nanoparticles (NPs) attached on FeNi nanorods (NRs) surface loosely. The catalytic reactivity monitored by means of a UV-vis dynamic process shows FeNi@Ni nanocables can catalyse the transformation of p-nitrophenol to p-aminophenol completely under an ambient atmosphere at room temperature, and enable the catalysis to be more efficient than its counterparts FeNi NRs and Ni NPs due to the interfacial synergistic effect. Additionally, the resultant hierarchical metal–alloy nanocomposites possess ferromagnetic behaviour, and can be easily separated and recycled by an external magnet field for application.
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PROGRESS IN ORGANIC COATINGS
·
2016
·
IF 2.632
Huijing Li,Junjie Yuan,He Qian,Limin Wu
In this study, we have successfully introduced siloxane monomer, 2,4,6,8-Tetravinyl-2,4,6,8-tetramethylcyclotetrasiloxane (V 4 ) into the shell of silica/poly(methyl methacrylate-butyl acrylate) (SiO 2 /P(MMA-BA)) core–shell nanocomposite colloids via in-situ emulsion copolymerization. The obtained nanocomposite films with 50% silica content all show excellent transparency (nearly 100% transmittance in visible range) and film-forming property (T g under 30 °C). More importantly, the addition of V 4 can significantly increase the weathering durability of the film by improving the water repellency, cross-linking degree and UV-blocking property of the film.
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