Nanoscale
·
2021
·Vol. 14
·期 5
·1796-1806
·
IF 7.79
Wenyan Yin,Milin Zhang,Jingyuan Liu,Khaled Tawfik Alali,Jing Yu,Jiahui Zhu,Peili Liu,Rumin Li,Jun Wang
Electrochemical sensors using ionic liquids as electrolytes for oxygen detection are now getting more and more attention. Recently, an ionic liquid combined with an electrochemically active catalyst system has become popular for boosting the sensing performance of oxygen sensors. In this work, the imidazolyl-based ionic liquid 1-butyl-2,3-dimethylimidazole bis((trifluoromethyl)sulfonyl)imide [Bmmim][TFSI] is first prepared by a facile two-step method. Subsequently, a transition metal and N-codoped porous carbon oxygen reduction electrochemical catalyst Cu–N/C is synthesized by calcining the Cu-doped ZIF-8 precursor and then blending it in different ratios with the ionic liquid [Bmmim][TFSI] as composite electrolytes for oxygen detection. The composite electrolyte Cu–N/C/[Bmmim][TFSI] exhibits increased responses in cyclic voltammetry (CV) and chronoamperometry (CA) relative to that of the pure ionic liquid. Furthermore, the CV and CA data show that 6% Cu–N/C/[Bmmim][TFSI] has the optimum oxygen sensing response with an enhanced reduction peak current, a sensitivity of 0.1678 μA/[% O2] and a good linear fitting coefficient of 0.9991. In conclusion, the results confirm the success of using Cu–N/C as an electrochemical catalyst composed of the Cu–N/C/[Bmmim][TFSI] electrolyte for improving the responsivity, stability and sensitivity towards a wide range of oxygen concentrations.
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JOURNAL OF MEMBRANE SCIENCE
·
2021
·
IF 8.742
Sixing Chen,Yi Liu,Yanwei Sun,Guoliang Xu,Taotao Ji,Xiongfu Zhang,Fei Wang,Yi Liu
Concurrent manipulation of orientation and thickness of MOF membranes has become a reliable approach for improving their separation performances. In terms of oriented seeded growth, oriented deposition of MOF nanosheets during seeding process and sealing all intergranular gaps with no discernible increase in membrane thickness during secondary growth have become indispensable. In this study, we pioneered the fabrication of uniform hexagonal-shaped, 20–40 nm thick MIL-96 nanosheets through solvent composition optimization (V H2O /V FA = 1/2). Subsequently, spin coating was employed for c -oriented deposition of uniform MIL-96 seed layer, during which the addition of PVP in the suspension was found to be critical for obtaining qualified seed layer. Finally, well-intergrown, highly c -oriented ultrathin MIL-96 membrane was prepared upon employing NMF as the solvent during secondary growth. Gas permeation results implied that prepared MIL-96 membrane exhibited superior gas separation performance compared with that of a -& b -oriented counterpart.
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高影响因子
IONICS
·
2021
·Vol. 27
·期 9
·3975-3985
·
IF 2.817
Wang Zhiyi,Wang Yutian,Tang Jingtao,Wang Kaizhao,Chen Tianyou,Wang Kaijun,Hu Jin
Among the currently studied nitrogen-doped Pt-C catalysts, the environmental friendliness of the nitrogen source and the stability of Pt-C catalysts for fuel cells are urgent issues to be solved. In this study, nitrogen-doped platinum-based catalyst (CSC/BP-Pt) with excellent stability for the ORR is prepared by a self-doping method based on chitosan (CS), a green biomass material with both nitrogen and carbon sources, in combination with conductive carbon black (BP2000). Finally, the N content of the catalyst is as high as 5.8 wt%, which is higher than most comparable catalysts (3–5 wt%). And electrochemical tests show that the CSC/BP-Pt electrochemical active surface area (ECSA) = 154.1 m 2 /g Pt , half-wave potential (E 1/2 = 0.85 V RHE ) has a better electrochemical performance than the commercial Pt/C (20 wt%), while the half-wave potential is reduced at 10,000 cycles of cyclic voltammetry with almost no attenuation (only 7 mVcompared to 31 mV of Pt/C). Besides, possible mechanisms to improve the activity and stability of CSC/BP-Pt are preliminarily proposed.
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Reaction Kinetics Mechanisms and Catalysis
·
2021
·Vol. 133
·期 1
·371-382
·
IF 2.081
Song Wenjing,Song Mengxue,Jiang Xingmao,Yi Xiaodong,Lai Weikun
Hydrolytic cleavage of C–O bond was systematically studied in acidic/alkaline aqueous solution. For phenethoxybenzene (PEB) hydrolysis, 2-phenylethanol and phenol were formed as main products in AlCl 3 solutions, whereas styrene was preferred with Na 2 CO 3 . After a quantitative evaluation of the kinetics of elementary steps, it was concluded that both AlCl 3 and Na 2 CO 3 promoted protons assisted C–O bond scission in H 2 O, whereas alkaline enhanced the dehydration of produced 2-phenylethanol. Kinetic and isotope labeling experiments demonstrated that the hydrolytic rates of PEB were first order with respect to substrate concentrations, hydrolytic cleavage of C–O bond was rate-determining step. The study shed light on the promotional effects and hydrolytic mechanism over acid/base-catalyzed lignin depolymerization in water. Graphic abstract
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Catalysts
·
2021
·Vol. 11
·期 8
·925
·
IF 4.146
Qijun Wang,Ya-Wei Zhou,Zhao Jin,Chunguang Chen,Hong Li,Wen-Bin Cai
Carbon-supported PtRu nanoalloy (PtRu/C) is widely used as the anode catalyst for direct methanol fuel cells (DMFC), and an aqueous phase synthesis of PtRu/C is in high demand due to for energy-saving and environmentally-benign considerations, however, it is very challenging to attain stoichiometric reduction, good dispersion and a high alloying degree. Herein, we report a facile aqueous phase approach with dimethylamine borane (DMAB) as the reducing agent to synthesize a PtRu/C(DMAB). TEM, XRD, XPS and ICP-AES characterizations indicate that the structural parameters in the PtRu/C(DMAB) are improved significantly as compared to those obtained in a PtRu/C(NaBH4) and a commercial PtRu/C, contributing to an enhanced electrocatalytic performance. It turns out that the PtRu/C(DMAB) exhibits the highest methanol electro-oxidation (MOR) performance among all of the tested samples, with the peak current up to 1.8 times as much as that of the state-of-the-art commercial PtRu/C, corroborating the highest output power density in comparative DMFC tests. In-situ attenuated total reflection infrared (ATR-IR) spectroscopy correlates the higher methanol electro-oxidation performance of the PtRu/C(DMAB) with its enhanced CO resistance and CO2generation. This simple aqueous synthetic approach may provide an alternative route for developing efficient anode electrocatalysts of DMFCs.Keywords:PtRu/C catalyst;methanol electro-oxidation reaction;aqueous phase synthesis;dimethylamine borane;direct methanol fuel cell;in-situ ATR-IR
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Journal of the Taiwan Institute of Chemical Engineers
·
2021
·
IF 5.876
Xiuhui Zhai,Xiang Wang,Xinle Pang,Jun Zhang,Qiong Wu,Weidan Na,Yingmei Zhou,Lin Tian
Exploiting effective and low-cost electrocatalysts toward water oxidation is of vital significance for boosting overall water splitting. Herein, we proposed a simple method for constructing dendritic N-doped carbon/ manganese oxides (N-C/MnO x ) hybrid nanocomposites by annealing the composite of nitrogen-doped carbon quantum dots (N-CQDs) and γ-MnOOH (γ-MnOOH@N-CQDs) at different temperatures under N 2 /O 2 atmosphere. The obtained N-C/MnO x exhibited remarkable electrocatalytic activity and stability for oxygen evolution reaction (OER) owing to their unique dendritic structure, rich oxygen vacancies, optimized electronic structure, abundant Mn-C/N, and large electrochemical active area. Among of the prepared N-C/MnO x hybrid nanocomposites, N-C/Mn 2 O 3 showed the best performance toward OER with an overpotential of merely 347 mV to reach to 10 mA cm −2 , along with a small Tafel slope of 75.51 mV dec −1 . More remarkably, by combining Pt/C with N-C/Mn 2 O 3 for overall water splitting, a battery voltage of only 1.67 V is needed to reach the 10 mA cm −2 , rivaling the activity of the state-of-the-art IrO 2 ‖ Pt/C couple.
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高影响因子
WEAR
·
2021
·
IF 3.892
F.S. Meng,Z. Li,H.H. Ding,J.S. Hu,W.J. Wang,J. Guo,Q.Y. Liu
The advanced nano-additives can improve the lubrication performance of nanolubricants efficiently, which could greatly reduce energy consumption. Here, we prepared the BN coated with carbon layer (BN@C) by a novel hydrothermal coating method with pristine BN nanosheets as matrix material and glucose as carbon source. And the BN@C exhibited excellent lubrication performance as a lubricant additive . In order to investigate the tribological properties, BN@C was modified with oleic acid as a surfactant , and the friction tests were carried out on an MRS-10A four-ball friction and wear tester. Benefitting from the stable dispersity, ultrasmall particle size and the surface carbon layer of BN@C-OA, the lubrication performance was significantly improved. More impressively, BN@C-OA could enter the interface of friction pairs . The interlayer sliding occurred to improve the anti-wear and anti-friction properties. This study could provide a new avenue to synthesize the coating-containing nanocomposite additive to promote the lubrication properties of nanoparticles in oil.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2021
·
IF 5.316
Jiaxing Wen,Yi Pei,Li Liu,Die Su,Min Yang,Qianfu Wang,Wen Zhang,Jing Dai,Yan Feng,Tianjing Wu,Xianyou Wang
Both antimony selenide and antimony are promising anode materials for lithium-ion batteries. However, owing to the influence of the poor electronic conductivity of Sb 2 Se 3 and the large volume expansion of the two materials during the lithiation process, their electrochemical performance is limited and the practical application is restricted. In this work, for the first time, the hierarchical Sb 2 Se 3 and Sb particles fully encapsulated into carbon nanofibers (Sb 2 Se 3 /Sb/C nanofibers) have been in-situ synthesized by electrospinning followed by controlled annealing. Combining the advantages of high specific capacity of Sb 2 Se 3 , good electronic conductivities of Sb and C, and strong stability of C matrix, the Sb 2 Se 3 /Sb/C nanofibers electrode shows excellent lithium-storage performance. It achieves a high reversible capacity (764 mA h g −1 after 300 cycles at 0.1 A g −1 ), splendid ultralong cycling stability (429 mA h g −1 after 1000 cycles at 1 A g −1 ), and high rate capability (342 mA h g −1 at 5 A g −1 ). It demonstrates that Sb 2 Se 3 /Sb/C nanofibers are promising high-performance anode materials for lithium-ion batteries.
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ACS Catalysis
·
2021
·
IF 13.084
Muhong Li,Shanyong Chen,Qike Jiang,Qingliang Chen,Xuan Wang,Yong Yan,Jian Liu,Changchang Lv,Weiping Ding,Xuefeng Guo
The production of functionalized anilines by chemoselective hydrogenation of nitroarenes occupies an important position in the chemical industries. Recently, cobalt and nitrogen codoped carbon (Co–N–C) catalysts have been reported to show outstanding catalytic performance in this process, whereas the nature of their active sites is still at the center of intense debate. In this paper, based on the well-controlled experiments on four types of typical Co–N–C materials derived from different methodologies, several unusual generalities in the hydrogenation of nitroarenes are clearly revealed, including protic-solvent dependence, antipoisoning, acid resistance, and reversible deactivation. Further investigations indicate that the single-atom species Co–Nx are the main active sites of the Co–N–C catalysts in this chemoselective hydrogenation process. The present work sheds light on the mechanism study on the metal–N–C catalysts and further contributes to the rational design of the high-performance single-atom catalysts.
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ACS Sustainable Chemistry & Engineering
·
2020
·
IF 7.632
Zhiyan He,Guangxing Yang,Hongjuan Wang,Fengying Dai,Feng Peng,Hao Yu
Metal- and nitrogen-doped carbon materials (Me–N–C) have received intensive scientific interest as single-atom catalysts (SACs) for electro- and thermocatalytic reactions. In this work, the potential of Me–N–C (Me = Co, Fe, Ni)-wrapped carbon nanotubes (CNTs) as support of platinum nanoparticles (Pt NPs) for base-free oxidation of glycerol was investigated. Co-doping of transition metal and nitrogen significantly enhanced the dispersion of Pt, indicating the advantages of the supporting material for noble-metal catalysts. Two-fold improvement of turnover of glycerol was observed over 5Pt/CoNC@CNT compared to 5Pt/CNT under the same reaction conditions. A kinetics study was conducted to understand the role of CoNC as a support of Pt NPs in a wide range of oxygen partial pressure from 0.04 to 0.4 MPa and a range of glycerol concentration from 0.012 to 0.15 wt %. A synergistic effect between Me–N–C, especially Co–N–C, and Pt NPs was revealed. The Co–N–C support facilitated the activation of oxygen and thus enhanced the overall turnover of glycerol oxidation, especially at high glycerol concentrations. This finding suggests a new approach to the high-performance Pt catalysts via introducing SACs as supporting materials that afford auxiliary active sites for the target reaction.
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Journal of Environmental Sciences
·
2020
·
IF 4.302
Runping Wu,Qing Ye,Kai Wu,Hongxing Dai
To improve the removal capacity of NO + O 2 effectively, the alkaline earth metal-doped order mesoporous carbon (A-C-FDU-15(0.001) (A = Mg, Ca, Sr and Ba)) and Mg-C-FDU-15( x ) ( x = 0.001−0.003) samples were prepared, and their physicochemical and NO + O 2 adsorption properties were determined by means of various techniques. The results show that the sequence in (NO + O 2 ) adsorption performance was as follows: Mg-C-FDU-15(0.001) (93.2 mg/g) > Ca-C-FDU-15(0.001) (82.2 mg/g) > Sr-C-FDU-15(0.001) (76.1 mg/g) > Ba-C-FDU-15(0.001) (72.9 mg/g) > C-FDU-15 (67.1 mg/g). Among all of the A-C-FDU-15(0.001) samples, Mg-C-FDU-15(0.001) possessed the highest (NO + O 2 ) adsorption capacity (106.2 mg/g). The species of alkaline earth metals and basic sites were important factors determining the adsorption of NO + O 2 on the A-C-FDU-15( x ) samples, and (NO + O 2 ) adsorption on the samples was mainly chemical adsorption. Combined with the results of (NO + O 2 )-temperature-programmed desorption ((NO + O 2 )-TPD) and in situ diffused reflectance infrared Fourier transform spectroscopy (DRIFTS) characterization, we deduced that there were two main pathways of (NO + O 2 ) adsorption: one was first the conversion of NO and O 2 to NO 2 and then part of NO 2 was converted to NO 2 − and NO 3 − ; and the other was the direct oxidation of NO to NO 2 − and NO 3 − .
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CHEMICAL ENGINEERING JOURNAL
·
2020
·
IF 10.652
Lei Li,Guilin Li,Wenjun Ouyang,Yaping Zhang,Fanzhen Zeng,Chenyu Liu,Zhan Lin
The realization of balance between relative permittivity and permeability is still a great challenge in the development of microwave absorption materials. Based on the controllable MOFs precursor, bimetallic Fe/M (M = Co, Ni, Mn) doped carbon derived from pyrolyzing bimetallic MOFs (FeM-MIL-88B) exhibits intriguing microwave absorption property. By tuning the second metal source and the ratio of Fe/M, in this work we realize impedance matching between free space and the absorber. Optimized FeCo 2 @C exhibits strong EMW absorption performance (-71.4 dB) and broad bandwidth (14.2 GHz) with a low filler loading of 25 wt%. The synergistic effect of the bimetal source on carbonization process and electric/magnetic properties prove that rationally doping the second metal source into the Fe-MOFs precursor to generate bimetallic magnetic nanoparticles/C material play an intensified role to tune the microwave absorption performance.
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