Nanoscale
·
2019
·Vol. 11
·期 38
·17736-17745
·
IF 6.97
Qian Zhu,Fushan Wang,Fengwei Zhang,Zhengping Dong
The direct oxidation of alcohols to esters through a green and cost-effective strategy is a fascinating chemical synthesis route. In this study, an environmentally friendly N-doped porous carbon encapsulated Co-based nano-catalyst was prepared via a simple carbonization procedure, utilizing renewable chitosan, accessible dicyandiamide and low-cost Co(OAc)2 as co-precursors. The obtained Co@NC-2-T catalysts were successfully used in selective oxidation of aromatic alcohols with methanol to esters under atmospheric reaction conditions. The Co@NC-2-900 catalyst (added with 2 g dicyandiamide and pyrolyzed at 900 °C) shows optimal activity and applicability and can also be reused at least six times in the oxidative esterification of aromatic alcohols with excellent stability. The presence of superoxide anion radicals in the current catalytic system was detected by the EPR method, and a possible mechanism of alcohol oxidation to ester was proposed on this basis. Thus, this study provides a facile, eco-friendly, and highly efficient catalytic system for oxidative esterification of alcohols.
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2019
·
IF 7.015
Jiandang Xue,Xin Liu,Junfeng Zhang,Yan Yin,Michael D. Guiver
The knowledge that N -spirocyclic quaternary ammonium (QA) cations appear to have good alkaline stability has triggered the quest to incorporate these into anion exchange membranes (AEMs) with the anticipation of high operating stability in alkaline fuel cells . Herein, a series of poly(2,6-dimethyl-1,4-phenylene oxide)s (PPOs) incorporating spirocyclic 3,6-diazaspiro[5.5]undecane (DSU) cation/cation strings are synthesized by a two-step quaternization strategy. The properties of DSU-based single-cation and double-cation AEMs (PPO-SDSU and PPO-DDSU, respectively) are discussed and the effect of introducing heterocyclic quaternary piperidinium (Qpip) on spirocyclic DSU cation strings is investigated. Ionic clusters of larger size scattering are observed by atomic force microscopy for PPO-SDSU membranes, suggesting the dominant effect of polar tertiary nitrogen atom on the formation of ion cluster. The well-connected hydrophilic domains contributed to further increasing the water uptake and hydroxide conductivity of the AEMs. As a result, the PPO-SDSU membrane with ion exchange capacity (IEC) of 1.91 meq/g shows the highest hydroxide conductivity (31.9 mS/cm) with 76% water uptake and 9.6% linear dimensional swelling at 20 °C. Alkaline stability tests imply that the presence of Qpip in DSU cation strings alleviates the degradation of spirocyclic QA from S N 2 substitution, due to increased steric hindrance, but other considerations must address the potentially detrimental effect of Hofmann elimination on spirocyclic QA and PPO backbone scission, arising from the electron withdrawing effect of Qpip. Although hydroxide conductivity and IEC values were better retained for PPO-DDSU membranes, the inferior alkaline stability of the benzylic attached Qpip counteracted the overall stability enhancement anticipated for incorporating spirocyclic DSU cations. These results may provide valuable insights toward more effective molecular designs and new synthetic pathways to AEMs incorporating base-stable N -spirocyclic QA.
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2019
·
IF 6.361
Chao Zhang,Jinhe Shu,Shuxian Shi,Jun Nie,Guiping Ma
Biomass derived porous carbon was wildly used in non-precious metal carbon based electrocatalysts for ORR due to its low cost and sustainability. Here, we develop a facile route to prepare Co/N doped hemp derived highly porous carbon (Co/NHPC) as ORR electrocatalyst. The prepared Co/NHPC-90 possess 3D hierarchically porous nanostructure with high specific surface areas (1251 m 2 g −1 ) and large pore volumes (0.99 cm 3 g −1 ) due to the chemical activation of NaHCO 3 , which is benefit for the mass/electron transfer and exposure of active sites. In addition, melamine and cobalt nitrate were selected as nitrogen and metal source respectively to enrich the density of active sites. Thus, Co/NHPC-90 exhibits excellent ORR electrocatalytic performance with high half-wave potential (0.826 V), superior catalytic stability and tolerance to methanol.
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2019
·
IF 4.175
Yuwei Ye,Yangjun Zou,Zilong Jiang,Qiumin Yang,Liyong Chen,Shengda Guo,Hao Chen
N doped carbon dots (N-CDs) were prepared by hydrothermal method in methacrylic acid and n -butylamine precursors. The inhibition behavior of N-CDs on Q235 steel in hydrochloric acid environment was discussed via weight loss test, surface characterizations and electrochemistry measurements. Results showed that the as-prepared N-CDs could effectively protect Q235 steel and the inhibition efficiency reached up to 94.96% at 200 mg/L of N-CDs. In the meantime, the impedance modulus was greatly enhanced and the corrosion current density was reduced by one order of magnitude after the addition of N-CDs. Moreover, it could adhere to the steel surface by diffusion and agglomeration effect, resulting in the formation of adsorption film on steel surface. The adsorption mechanism of N-CDs almost complied with the Langmuir adsorption model, containing chemical and physical adsorptions.
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ELECTROANALYTICAL CHEMISTRY
·
2019
·
IF 3.218
Sumbal Farid,Weiwei Qiu,Jialin Zhao,Xuedan Song,Qing Mao,Suzhen Ren,Ce Hao
In recent years, a noticeable shifting from conventional fossil fuels to renewable energy based systems has embarked electrochemical splitting of water as the most promising way to produce clean energy of hydrogen. Generally, the lack of active and stable electrocatalysts for oxygen evolution reaction (OER) limits the practicability of water splitting as a renewable source of energy. In this work, interconnected 3D structure of cobalt oxides nanoparticles (Co 3 O 4 NPs) derived from ZIF-67 with nitrogen-doped carbon nanotubes (N-CNTs) of polypyrrole (PPy) origin is successfully synthesized as OER electrocatalysts. Impressively, the highly conductive N-CNTs that run through the Co 3 O 4 NPs not only endow the resulting product Co 3 O 4 /N-CNTs with large active surface area and enhanced charge transfer between Co 3 O 4 NPs, but also prevent Co 3 O 4 NPs from aggregation. As a result, the as-synthesized Co 3 O 4 /N-CNTs electrocatalyst exhibits outstanding OER activity with a low onset potential of ~1.37 V (vs RHE), overpotential of only 200 mV to attain a stable current density of 10 mA cm − 2 in basic media and very small Tafel slope of 40 mV dec − 1 . Moreover, the enhanced nitrogen-content also improves the OER kinetics by proficient charge transfer. The superb electrocatalytic performance and higher stability make the Co 3 O 4 /N-CNTs a proficient non-precious electrocatalyst for the OER.
✓ 已验证
产品关联
DOI
高影响因子
MATERIALS RESEARCH BULLETIN
·
2019
·
IF 3.355
Yanping Wang,Hua Yang,Xiaofeng Sun,Haimin Zhang,Tao Xian
We reported the preparation of new ternary n-BaTiO 3 /Ag/p-AgBr heterostructured photocatalysts and their promising photocatalytic application for the dye degradation. The ternary n-BaTiO 3 /Ag/p-AgBr heterostructured photocatalysts are constructed by coupling n-type BaTiO 3 and p-type AgBr particles onto Ag nanowires. Various methods including XRD, SEM, TEM, XPS, FTIR, UV–vis diffuse reflectance spectroscopy, PL spectroscopy, photocurrent response and EIS were used to characterize the as-prepared photocatalysts. The photodegradation performances of the photocatalysts were assessed by using RhB as the model pollutant and simulated sunlight as the light source. It is demonstrated that the n-BaTiO 3 /Ag/p-AgBr ternary composite photocatalysts exhibit excellent photodegradation performances superior to bare BaTiO 3 and AgBr particles. Particularly, the 20 %BTO/1.2 %Ag/AgBr composite can photocatalyze 99.3 % removal of RhB after 12 min photoreaction, and has a photodegradation activity which is about 3.1 times larger than that of bare AgBr particles. The underlying photodegradation mechanism of the ternary composite photocatalysts was investigated and discussed.
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
·
2019
·
IF 3.571
Xiumei Wang,Xiaoli Qin,Xiuting Li,Zexin Zhao,Bo Yang,Yonghua Wang
n-3 polyunsaturated fatty acid (PUFA)-rich lysophosphatidylcholine (LPC) with many beneficial effects was effectively synthesized by immobilized MAS1 lipase-catalyzed esterification of n-3 PUFA with sn-glycero-3-phosphatidylcholine (GPC) under vacuum in a solvent-free system. Immobilized MAS1 lipase was found to be a more suitable catalyst for the production of n-3 PUFA-rich LPC when compared with Novozym 435. The maximal GPC conversion and LPC content (93.12% and 90.77 mol %) were obtained under the optimized conditions (enzyme loading of 300 U/g substrate, temperature of 55 °C, and n-3 PUFA/GPC molar ratio of 20:1). Moreover, it was observed that 1-acyl-sn-glycero-3-lysophosphatidylcholine (sn-1 acyl LPC) was the main reaction product, as demonstrated by molecular docking. These results showed that immobilized MAS1 lipase had high phospholipase activity with a predominant specificity for the sn-1 hydroxyl position of GPC to efficiently synthesize highly pure n-3 PUFA-rich LPC from GPC for industrial application.
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2019
·
IF 6.361
Yulai Zhao,Mengzhi Wei,Zhongzheng Zhu,Jing Zhang,Longqiang Xiao,Linxi Hou
Biomass carbon materials which have the merits of green, low cost and renewability, can be obtained from sodium alginate (SA) beads crosslinked by polyvalent metal ions . SA beads are possible to be obtained using diammoniums as the crosslinking agents. In this work, N-O codoped porous carbon (NO-PC) was prepared from SA beads crosslinked by diammoniums through the electrostatic interaction between ammonium cations and carboxylate groups of SA chains. The using of diammoniums as the crosslinkers achieved N doping into NO-PC. Scanning and transmission electron microscope observations revealed that NO-PC possessed hierarchically porous characteristic. X-ray photoelectron spectroscopy identified the successful N-O codoping. Both the species and concentration of diammoniums strongly affected the porous structure, surface area and electrochemical performance of NO-PC. N 2 adsorption-desorption results of NO-PC indicated that the highest surface area was up to 3794 m 2 /g. The NO-PC based supercapacitors showed high specific capacities up to 269.0 F/g at 1 A/g and excellent cycling stability (92.09% after 5000 cycles at 5 A/g). The energy density of the symmetric supercapacitor was up to 18.9 Wh/kg at a power density of 1380 W/kg with a voltage window of −1.4–0 V.
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF ELECTROANALYTICAL CHEMISTRY
·
2019
·
IF 3.218
Chanez Maouche,Yazhou Zhou,Bing Li,Chao Cheng,Yunyan Wu,Jinghan Li,Shuai Gao,Juan Yang
N-doped graphene has attracted a considerable interest in the development of a new promising metal-free catalyst for oxygen reduction reaction (ORR) to replace platinum-based catalysts. Herein we reported a facile fabrication of three-dimensional N-doped graphene (GC) using graphitic carbon nitride (g-C 3 N 4 ) and graphene oxide (GO) as raw materials. Urea was used as a precursor of synthesizing g-C 3 N 4 and N doping. Thermal treatment has been done at different temperatures. As a result, a large surface area with a unique porous structure were obtained for the sample GC-900. Our catalyst showed an outstanding catalytic activity with superb stability and methanol tolerance. The structural characterizations of different materials demonstrated that the combination of an optimal heating temperature, a high nitrogen N content and a porous structure was essential for high ORR electrocatalytic activities .
✓ 已验证
产品关联
DOI
高影响因子
Energy Technology
·
2019
·Vol. 8
·期 1
·1901013
·
IF 3.163
Xufei Liu,Peng Mei,Sheng Lei,Xiaofang Zhang,Qian Liu,Yingkui Yang
3D N-doped carbon nanobelt (NCB) networks are fabricated by one-pot hydrothermal polycondensation of co-monomer salts of dianhydride and diamine followed by carbonization of the resulting nanobelt-like polyimides. As control samples, solvothermally polymerized petal-like polyimides and conventionally polymerized spindle-like polyimides are also produced, which further yields N-doped carbon petals and N-doped carbon spindles after identical carbonization, respectively. Interestingly, all N-doped carbons copy the morphologies of their polyimide precursors well. Specially, the 800°C-treated NCB exhibits a robust 3D architecture composed of intertwined nanobelt networks with high N-doping levels and electroactivity-enriched N configurations. Remarkably, the symmetric supercapacitor assembled by such NCB electrodes delivers large specific capacitance (193 F g −1 at 1 A g −1 ), high rate capability (176 F g −1 at 20 A g −1 ), and long cycling stability (nearly 100% retention over 10,000 cycles at 20 A g −1 ). The energy density is as high as 27 Wh Kg −1 at the power density of 500 W Kg −1 , and retains 24 Wh Kg −1 at the power density up to 20,000 W Kg −1 . This work opens up an affordable and scalable approach to the rational fabrication of heteroatom-contained carbon materials for high-performance supercapacitors with well-balanced power and energy output.
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Nano Materials
·
2019
·
IF 0
Hongxiang Zhang,Chunxia Wu,Canran Zhang,Bisheng Yan,Jiyuan Guo,Gangyi Zhu,Jun Dai
In this paper, we report the dual-wavelength green-light emission from zinc oxide (ZnO)-nanoseed-decorated p-GaN (gallium nitride)/n-ZnO nanorod/CsPbBr3 quantum dots (QDs) light-emitting diodes (LEDs). At the same time, the effect of ZnO nanoseeds on the p-GaN/n-ZnO nanorod/CsPbBr3 QDs LED performance is deeply studied. ZnO nanoseeds were fabricated by magnetron sputtering and the sol–gel method; then ZnO nanorods were obtained on GaN by hydrothermal treatment to form the p-GaN/n-ZnO nanorod heterojunction, and green CsPbBr3 QDs were further deposited on ZnO nanorod arrays to realize LEDs. The results show that magnetron-sputtering ZnO nanoseeds can induce regular vertical ZnO nanorod arrays, and the corresponding device presents a better electroluminescence (EL) performance. The X-ray diffraction, atomic force microscopy, and EL mechanisms indicate that the p-GaN/n-ZnO nanorod with magnetron-sputtering ZnO nanoseeds has a better crystalline interface. Our results indicate that the p-GaN/n-ZnO nanorod/CsPbBr3 QDs heterojunction structure can be served as dual-wavelength LEDs, and magnetron-sputtering ZnO nanoseeds can give rise to a better EL performance.
✓ 已验证
产品关联
DOI
CELLULOSE
·
2019
·Vol. 27
·期 3
·1745-1761
·
IF 3.917
Wan Caiyan,Liu Mingsheng,Tian Peixiu,Zhang Guangxian,Zhang Fengxiu
Abstract A bio-based P–N synergistic flame retardant ammonium salt of d -Panthenol-tri (methylphosphonic acid) (ADPTMPA) was synthesized using a formaldehyde-free and solvent-free strategy for the highly efficient preparation of durable flame-retardant cotton. The ADPTMPA structure was verified by 1 H NMR, 13 C NMR and 31 P NMR. FT-IR test revealed successful grafting of the flame retardant onto the cotton through P–O–C covalent bonding. The morphologies and structures of pure cotton and treated cotton were characterized by SEM and XRD, and the elemental compositions of cotton samples were analyzed by EDX. Volatile pyrolysis products of treated cotton were analyzed by TG-IR. Flame retardancy and washability of treated cotton were analyzed by limiting oxygen index (LOI) and vertical flammability tests (VFT). The LOIs of 40 wt% ADPTMPA treated cotton before and after 50 laundering cycles was determined as 46.5% and 35.8%, respectively. VFT showed the treated cotton exhibited no smoldering and continuous burning. All carbon lengths of treated cottons were less than 60 mm. The heat release rate and total heat release of treated cotton were decreased by 91.34% and 58.01% compared with pure cotton, respectively. There was 29.42 wt% carbon residual remaining when the treated cotton was exposed to heat flow of 35 kw/m 2 . The treated cotton exhibited excellent flame retardancy and washability. Additionally, the mechanical properties and whiteness of the treated cotton were well-maintained. Graphic abstract
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）