Entropy
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2020
·Vol. 22
·期 12
·1337
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IF 2.494
Xiangfeng Tian,Lemeng Wang,Pan Zhang,Dong Fu
The surface tension and viscosity values of N-methyldiethanolamine (MDEA) aqueous solutions promoted by tetramethylammonium arginate ([N1111][Arg]) were measured and modeled. The experimental temperatures were 303.2 to 323.2 K. The mass fractions of MDEA (wMDEA) and [N1111][Arg] (w[N1111][Arg]) were 0.300 to 0.500 and 0.025 to 0.075, respectively. The measured surface tension and viscosity values were satisfactorily fitted to thermodynamic models. With the aid of experimentally viscosity data, the activation energy (Ea) and H2S diffusion coefficient (DH2S) of MDEA-[N1111][Arg] aqueous solution were deduced. The surface entropy and surface enthalpy of the solutions were calculated using the fitted model of the surface tension. The quantitative relationship between the calculated values (surface tension, surface entropy, surface enthalpy, viscosity, activation energy, and H2S diffusion coefficient) and the operation conditions (mass fraction and temperature) was demonstrated.Keywords:surface thermodynamics;viscosity;MDEA;[N1111][Arg]
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Materials Today Chemistry
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2021
·
IF 8.301
J. Zhu,C. Shang,X. Wang,G. Zhou
Phosphorus-based materials as the anode for sodium-ion batteries have drawn extensive attention because of their high theoretical capacity and low insertion potential. Nevertheless, the severe volume variation and low electric conductivity hindered their further practical applications. Herein, a novel Co 2 P/Sn 4 P 3 hybrid encapsulated in carbon nanocubes was fabricated by a coprecipitation method followed by phosphating progress. Accompanying with the N, P codoping and abundant grain boundaries, which facilitates electric transport and provides rich active sites, the as-synthesized Co 2 P/Sn 4 P 3 @C anode delivered a high charge specific capacity of 185.6 mA h g −1 after 400 cycles at the current density of 1000 mA g −1 and outstanding cycling stability with a high capacity retention of 86.9%. Kinetics exploration indicated that the capacity was governed by the surface pseudo-capacitive controlled process due to the abundant defects originated from heteroatom doping and grain boundaries.
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Journal of Materials Chemistry C
·
2020
·Vol. 8
·期 42
·14723-14731
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IF 7.059
Lele Li,Liwei Yang,Si Zhang,Yuping Sun,Fen Li,Tengteng Qin,Xiaoqiang Liu,Yanmei Zhou,Subbiah Alwarappan
Herein, we designed a NiCo2S4@N/S–CeO2 composite with amplified electrocatalytic oxygen reduction (OR) capability by the in situ growth of NiCo2S4 nanoparticles on CeO2 nanospheres with simultaneous doping of nitrogen and sulfur. After optical characterization of the composite, it was then employed as the signal amplification label for constructing an electrochemical aptasensor. The composite provides a biocompatible and large surface platform to load biomolecules and retain their bioactivity. More importantly, the composite shows a comparable electrocatalytic OR capability similar to a commercial Pt/C catalyst and far better than CeO2, attributed to the NiCo2S4 deposition and oxygen vacancies introduced by N and S doping. Furthermore, the Koutecky–Levich plots indicate a nearly four-electron transfer pathway of the ORR. The as-prepared aptasensor exhibited a highly sensitive and selective determination of a model analyte-sulfadimethoxine with a wide linear range of 0.05–180 nM, a low detection limit of 0.02 ± 0.0011 nM and good feasibility for real-sample detection. This work paved an effective way for the design of highly efficient electrocatalysts with bright prospects in bioanalytical applications.
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Nano Research
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2020
·Vol. 13
·期 9
·2420-2426
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IF 8.183
Luo Ergui,Wang Chen,Li Yang,Wang Xian,Gong Liyuan,Zhao Tuo,Jin Zhao,Ge Junjie,Liu Changpeng,Xing Wei
Fe/N/C material is the most competitive alternative to precious-metal catalysts for oxygen reduction. In view of the present consensus on active centers, further effort is directed at maximizing the density of single Fe atoms. Here, the imperfections in commonly used doping strategy of Fe for the synthesis of zeolitic imidazolateframework (ZIF)-derived Fe/N/C catalysts are revealed. More importantly, a strikingly improved catalyst is obtained by a ‘second pyrolysis’ method and delivers a half-wave potential of 0.825 V (vs. RHE) in acidic media. The strong confinement effect of carbonaceous host accounts for the formation of dense single-atom sites and thus the high activity. Our findings will potentially facilitate future improvement of M/N/C catalysts.
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Applied Nanoscience
·
2020
·Vol. 10
·期 7
·2189-2198
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IF 2.88
Zhang Lin-Jiong,Feng Lian-Fang,Gu Xue-Ping,Zhang Cai-Liang
Poly( N -isopropylacrylamide) (PNIPAAm) hydrogel with temperature-sensitive properties can be potentially applied in smart response area. However, poor mechanical and non-conductive characteristic have greatly restricted its widespread application. In this work, PNIPAAm composite hydrogels containing graphene aerogel (GA) and graphene oxide (GO) were prepared via vacuum-assisted backfilling and in-situ polymerization. After an introduction of 0.29 wt% GA and 0.09 wt% GO, the compressive strength and modulus of PNIPAAm hydrogel increase by 100% and 582%, respectively. Moreover, the ternary composite hydrogel has a good electric conductivity, reaching up to 0.52 S/m, due to the electro-conductive network of GA. Combining the good conductivity and itself temperature-sensitive property of PNIPAAm, a smart switch was assembled and could switch off automatically under a high voltage, which has potential applications in sensor area.
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ChemElectroChem
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2020
·Vol. 7
·期 7
·1775-1780
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IF 4.154
Xinyue Zhang,Qingtao Liu,Jianglan Shui
Graphical Balancing act : Polytetrafluoroethylene (PTFE) is added to different positions of the Fe−N−C catalyst layer by using three methods to adjust its hydrophobicity. An appropriate amount of PTFE in the Fe−N−C catalyst layer is beneficial to the power density of the PEM fuel cell. However, the hydrophobicity of the Fe−N−C catalyst layer does not affect the long-term durability of the fuel cells, although high hydrophobicity will improve the fuel cell initial durability. The hydrophobicity of the cathode catalyst layer (CCL) affects the performance of the proton exchange membrane fuel cell (PEMFC) by adjusting the water management of the catalyst layer, which has been extensively studied in Pt-based catalysts. Here, the effect of the hydrophobicity of Fe−N−C CCL on the performance of the PEMFC is investigated. The hydrophobicity of the Fe−N−C CCL is tuned by polytetrafluoroethylene (PTFE) by using three addition methods: 1) coat PTFE on Fe−N−C powder and heat-treat; 2) mix PTFE emulsion with Fe−N−C ink and then brush the electrode; and 3) transfer a ground PTFE/Fe−N−C composite film onto the gas diffusion layer by the decal method. For each PTFE addition method, the optimized PTFE amount can increase the power density of Fe−C−N PEMFC by 15.1 %, 26.6 %, and 87.2 %, respectively. At the same time, it is found that enhanced hydrophobicity reduces the initial current decay rate of the Fe−N−C CCLs, but their residual current densities are close after a 50 h durability test at 0.5 V in a H 2 -O 2 PEMFC. It can be concluded that the hydrophobicity of the Fe−N−C CLL has a great influence on the power density of the fuel cell, but the influence on the long-term durability of the fuel cell is negligible.
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JOURNAL OF ELECTROANALYTICAL CHEMISTRY
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2020
·
IF 3.807
Cong Luo,Jianghua Yang,Jinling Li,Shijie He,Bowen Meng,Tao Shao,Qiankun Zhang,Dongxia Zhang,Xibin Zhou
A strategy for the synthesis of Au@N-CQDs@Pd three-layer core-shell nanoparticles without the use of any surfactant is proposed in this work. Herein, N-doped carbon quantum dots (N-CQDs) are used as the reducing agent, stabilizing agent, and shape-directing agent. The morphology and structure of the final product were characterized by Transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and X-ray powder diffraction (XRD). The electrocatalytic test indicates the as-synthesized Au@N-CQDs@Pd 20 exhibites excellent activity for methanol oxidation in alkaline media, which is approximately 6 times higher than commercial Pd/C. And its resistance to CO and stability are also greatly improved. This work provides a simple and straightforward approach to prepare bimetallic core-shell electrocatalyst by using CQDs with high catalytic activity for alkaline fuel cells .
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JOURNAL OF ELECTROANALYTICAL CHEMISTRY
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2020
·
IF 3.807
Shuo Geng,Shichong Xu,Yong Sheng Yu,Weiwei Yang,Ming Feng,Haibo Li
It is important to develop highly efficient and durable electrocatalysts for overall water splitting in industry application. Herein, we synthesized a novel 1D pea-like nitrogen-doped bimetallic carbide (N-Co 6 Mo 6 C) nanorods . Benefiting from the synergistic effect of N doping and good conductivity of the thin amorphous carbon shell on the surface of N-Co 6 Mo 6 C, the N-Co 6 Mo 6 C shows remarkable activity for both hydrogen evolution reaction (HER) in acid and alkaline solution and oxygen evolution reaction (OER) in alkaline solution, respectively. Furthermore, using the N-Co 6 Mo 6 C as both the anode and the cathode for overall water splitting, a cell voltage of only 1.58 V is needed to derive a current density of 10 mA/cm 2 . This work offers a new insight for the design of the non-noble bimetallic carbide with excellent electrocatalytic performance for overall water splitting.
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INORGANIC CHEMISTRY
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2020
·
IF 4.825
Zi-He Meng,Song-Hai Wu,Shi-Wei Sun,Zhi Xu,Xiao-Cong Zhang,Xiang-Ming Wang,Yong Liu,Hai-Tao Ren,Shao-Yi Jia,He Bai,Xu Han
The MnII(HCO3–)–H2O2 (MnII-BAP) system shows high reactivity toward oxidation of electron-rich organic substrates; however, the predominant oxidizing species and its formation pathways involved in the MnII-BAP system are still under debate. In this study, we used the MnII-BAP system to oxidize As(III) in that As(III), Mn2+, and HCO3– are common components in As(III)-contaminated groundwater. Kinetic results show that MnII(HCO3–)n [including MnII(HCO3)+ and MnII(HCO3)2] is a key factor in the MnII-BAP system to oxidize As(III). Quenching experiments rule out contributions of OH• and 1O2 to As(III) oxidation and reveal that O2•– and the oxidizing species generated from O2•– play predominant roles in the oxidation of As(III). We further reveal that the MnO2+(HCO3–)n intermediate generated in the reaction between MnII(HCO3–)n and O2•–, instead of O2•–, is the predominant oxidizing species. Although CO3•– also contributes to As(III) oxidation, the high reaction rate constant between CO3•– and O2•– indicates that CO3•– is not the predominant oxidizing species in the As(III)-MnII-BAP system. In addition, the presence of Mn(III) further indicates the important Mn(II)–Mn(III) cycling in the MnII-BAP system. We therefore suggest two important roles of MnII(HCO3–)n in the MnII-BAP system: (i) MnII(HCO3–)n reacts with H2O2 to form the MnIII(HCO3)3 intermediate, followed by a subsequent reaction between MnIII(HCO3)3 and H2O2 to produce O2•–; (ii) MnII(HCO3–)n can also stabilize O2•– with the formation of MnO2+(HCO3–)n. MnO2+(HCO3–)n is an electrophilic reagent and plays the predominant role in the oxidation of As(III) to As(V).
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APPLIED CATALYSIS B-ENVIRONMENTAL
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2020
·
IF 16.683
Bin Wang,You-Tao Chen,Tie-Yan Chang,Zhao Jiang,Zheng-Qing Huang,Si-Yao Wang,Chun-Ran Chang,Yu-Sheng Chen,Jin-Jia Wei,Sen Yang,Tao Fang
Facet structure plays an important role in many reactions. Generally, dehydrogenation reactions with only C H bond cleavage are often considered as structure insensitive reactions and therefore, there is no report on facet effect in reactions of LOHC for now. Herein, we report a facile synthesis of Pd nanoparticles enclosed by {100}, {110} and {111} facets supported on reduced graphene oxide. Combined with catalyst characterization, dehydrogenation performance study and DFT calculations, we found that the conversion rate and selectivity were strongly correlated with the facet structure of Pd, and {100} facet exhibited superior activity. We also identified the rate-determining step in the dehydrogenation of tetrahydro-N-ethylcarbazole to N-ethylcarbazole on Pd {100} facet. This work provides a basis for research requiring template Pd catalysts on rGO and broaden design methods for LOHC catalysts.
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JOURNAL OF HAZARDOUS MATERIALS
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2020
·
IF 9.038
Yaoping Hu,Zhijin Gao
Crystal violet (CV), a hazardous dye, poses a serious threat to the environment and human health. This motivates us to develop a facile method for its sensitive detection. Herein, we demonstrate a rapid sensing of CV using a novel fluorescent nanomaterial, yellow emissive Se,N-codoped carbon dots (CDs). CDs with an intense photoluminescence peak at 566 nm are synthesized by a hydrothermal technique using selenourea and o-phenylenediamine as precursors. This material shows a high quantum yield of up to 16.7 %. It is found that the yellow fluorescence of CDs can be selectively quenched by CV, which makes them promising for CV sensing. The linearity is obeyed in the range of 0.02–1.60 μM, and the limit of detection is as low as 7.3 nM. After detailed investigations, the inner filter effect is proposed to be the sensing mechanism. For practical usage, the newly built method is applied to determine the trace amount of CV in fish tissue samples, and satisfactory results are obtained.
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SURFACE AND INTERFACE ANALYSIS
·
2021
·Vol. 53
·期 12
·1027-1034
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IF 1.607
Qi Chen,Renhui Zhang,Zhongyi He,Liping Xiong
N-containing heterocyclic compound (NCHC) was a common used green lubricant addictive due to their extreme pressure, antiwear and friction–reduction performance, and high thermal stability, and ethylene glycol (EG) as lubricant exhibited superior tribological performance, combining of NCHCs, which was a suitable candidate for further improving the tribosystems' tribological properties. Thus, in this work, the synergistic effect between EG and 2,4,6-Tris(2-pyridinyl)-s-triazine (TPT) on the tribological performance was explored coupling of the applied loads and rotational speed. The tribological tests showed that TPT played an important role in improving the tribological properties as sliding in TPT@EG; the formation of the tribofilms induced by tribochemical reaction was in charge of enhancing the tribosystem's lubrication performance sliding in TPT@EG.
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