On the study of high temperature proton exchange membrane (HTPEM), the trade-off between proton conductivity and physico-chemical property (such as mechanical strength, dimensional stability and ...methanol resistance) remained a main obstacle for comprehensive performance enhancement. To address this issue, novel HTPEM was prepared by doping phosphotungstic acid intercalated ferric sulfophenyl phosphate (FeSPP-PWA) into polybenzimidazole (PBI) via hot pressed method. Intense hydrogen bonding network was built between PBI and FeSPP-PWA, rendering construction of proton channels and reinforcement of physico-chemical property. As a novel proton conductor, FeSPP-PWA facilitated formation of efficient proton transfer pathway. The layered morphology and inorganic intrinsity of FeSPP-PWA also improved the mechanical and dimensional stability while reducing the methanol permeability of the PBI/FeSPP-PWA membranes. The composite membrane exhibited good thermal stability up to 200 °C. The proton conductivity of PBI/FeSPP-PWA (30 wt%) reached 110 mS cm−1 at 170 °C and 100% RH, and was 69.3 mS cm−1 at 180 °C and 50% RH. The PBI/FeSPP-PWA also showed low methanol permeability and high membrane selectivity for application in direct methanol fuel cells.
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•A novel intercalated proton conductor (FeSPP-PWA) was doped into PBI to prepare PEMs.•Intense hydrogen bonding networks (IHBNs) were constructed between FeSPP-PWA and PBI.•The IHBNs provided proton channels and reinforced the physicochemical properties.•Good proton conductivity was reached at different humidity at high temperature.•Low methanol crossover and high membrane selectivity was achieved for PBI/FeSPP-PWA.
Exploring the oxygen electrocatalysts with both high oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) performance is crucial to developing the rechargeable Zn–air batteries (ZABs). ...Herein, we prepared a bifunctional three-dimensional graphene-like iron-nitrogen doped oxygen electrocatalyst (3D Fe/N-G#4, polyacrylamide (PAM):NaCl = 1:4, mass ratio) by a facile synthesis with PAM and iron as precursors and NaCl as template. The NaCl template melted during the pyrolysis process, which could fabricate a stable 3D network structure in the precursors to form more mesopores, higher specific surface area, and more exposed active sites and prevent the loss of precursors. The low-cost and water-soluble PAM as the N precursor provided abundant N and dissolved adequately with NaCl solution. The Fe precursor coordinated with the N to form Fe-N x active sites that were investigated by HR-TEM, XRD, XPS, and RDE techniques. The 3D Fe/N-G#4 exhibited excellent electrochemical activity with a high half-wave potential (0.852 V vs RHE) for ORR and a low overpotential (393 mV at 10 mA cm–2) for OER in the alkaline conditions. In addition, the homemade rechargeable ZAB based on the prepared 3D Fe/N-G#4 exhibits high power density (168.2 mW cm–2) and excellent discharge-charge cycling stability (over 60 h) at 20 mA cm–2. This work provides a cost-efficient, simple, and eco-friendly method to synthesize excellent bifunctional non-noble electrocatalysts for commercialization of ZABs.
Lunar laser ranging (LLR) has made major contributions to our understanding of the Moon’s internal structure and the dynamics of the Earth–Moon system. Because of the recent improvements of the ...ground-based laser ranging facilities, the present LLR measurement accuracy is limited by the retro-reflectors currently on the lunar surface, which are arrays of small corner-cubes. Because of lunar librations, the surfaces of these arrays do not, in general, point directly at the Earth. This effect results in a spread of arrival times, because each cube that comprises the retroreflector is at a slightly different distance from the Earth, leading to the reduced ranging accuracy. Thus, a single, wide aperture corner-cube could have a clear advantage. In addition, after nearly four decades of successful operations the retro-reflectors arrays currently on the Moon started to show performance degradation; as a result, they yield still useful, but much weaker return signals. Thus, fresh and bright instruments on the lunar surface are needed to continue precision LLR measurements. We have developed a new retro-reflector design to enable advanced LLR operations. It is based on a single, hollow corner cube with a large aperture for which preliminary thermal, mechanical, and optical design and analysis have been performed. The new instrument will be able to reach an Earth–Moon range precision of 1-mm in a single pulse while being subjected to significant thermal variations present on the lunar surface, and will have low mass to allow robotic deployment. Here we report on our design results and instrument development effort.
The rational design of highly efficient and durable oxygen reduction reaction (ORR) catalysts is critical for the commercial application of fuel cells. Herein, three‐dimensional graphene (3D‐G) is ...synthesized by the template method, which used coal tar pitch as the carbon source and nano MgO as the template. Then, spinel MnCo2O4 is in situ supported on the 3D‐G by a facile hydrothermal method, giving MnCo2O4/3D‐G. The resultant MnCo2O4/3D‐G retains the multilayered mesoporous graphene structure where MnCo2O4 nanoparticles are deposited on the inner walls of pores in the 3D‐G. The catalyst MnCo2O4/3D‐G shows high electrocatalytic activity with a half‐wave potential of 0.81 V versus reversible hydrogen electrode, which is clearly superior to those of MnCo2O4/reduced graphene oxide (0.78 V), MnCo2O4/carbon nanotubes (0.74 V), MnCo2O4/C (0.72 V), and 20 wt % Pt/C (0.80 V). The electron transfer number of MnCo2O4/3D‐G indicates a four‐electron process of ORR. The durability test demonstrates that the MnCo2O4/3D‐G catalyst has a much better durability than 20 wt % Pt/C. Our work makes an inspiring strategy to prepare high‐performance electrocatalysts for the development of fuel cells.
Three‐dimensional graphene (3D‐G) was synthesized by the template method. Then, spinel MnCo2O4 was in situ supported on the 3D‐G. The resultant MnCo2O4/3D‐G retains the multilayered mesoporous graphene structure where MnCo2O4 nanoparticles are deposited on the inner walls of pores in the 3D‐G. The catalyst MnCo2O4/3D‐G shows high electrocatalytic activity with a half‐wave potential of 0.81 V versus reversible hydrogen electrode.
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•Amorphous MnO2 supported by CNT-OH catalyst is prepared by the simple method.•The a-MnO2 has large lattice defects which can improve the ORR performance.•a-MnO2 grows near the ...hydroxyl groups which can improve the dispersity of a-MnO2.•COMn forms during the heat treatment which can enhance the durability of catalysts.•The magnesium–air fuel cell used a-MnO2/CNTs-OH as catalyst has good performance.
Amorphous MnO2/CNTs-OH (a-MnO2/CNTs-OH) was prepared by direct reaction method and then heat treated at 400°C under an argon atmosphere. The morphology characteristics indicate that MnO2 is amorphous and highly dispersed. The X-ray diffraction and X-ray photoelectron spectroscopy reveal that the existent form of manganese is a-MnO2. The oxygen reduction reaction performance investigated using a rotating disk electrode shows that the initial reduction potential of a-MnO2/CNTs-OH and a-MnO2/C are 0.905 and 0.844V (vs. RHE). The Tafel slopes are 88.9 and 127.35V dec−1, respectively. The electron transfer numbers are 3.92 and 3.8, respectively, corresponding to a four-electron process. The stability experiments of liner sweep voltammogram show that a-MnO2/CNTs-OH decreases by 0.155mAcm−2 after scanning for 200 cycles at the rotating rate of 1500rpm with a sweep rate of 5mVs−1. In I-t curves, the oxygen reduction current density of a-MnO2/CNTs-OH and a-MnO2/C decreases by 19.69% and 34.7% after 60h. Single cell tests of magnesium-air fuel cells show that the peak power densities of a-MnO2/CNTs-OH and a-MnO2/C are 79.2 and 62.4mWcm−2, respectively, and a-MnO2/CNTs-OH catalyst can continuously discharge for more than15h at 50mAcm−2.
Composite high temperature proton exchange membranes (HT-PEMs) comprising poly4,4′-(diphenyl ether)-5,5′-bibenzimidazole (oPBI), ferric sulfophenyl phosphate (FeSPP) and glass fiber (GF) were ...prepared by the hot-pressing method. Doping FeSPP as a novel insoluble proton conductor not only provided good proton conductivity at high temperature but also enhanced their methanol blocking property, dimensional stability and oxidative resistance. Good dispersion, construction of proton channels and reinforcement of the physicochemical properties were achieved by building hydrogen bonding network among oPBI, FeSPP and GF. After incorporation of 3wt% GF into the oPBI/FeSPP(30wt%) composite membrane, the tensile strength was enhanced by 370% while the swelling ratio reduced to around 55%. The oxidative stability and methanol resistance were also enhanced while the proton conductivity was slightly affected. The membranes were thermally stable in the working temperature range for HT-PEM fuel cells. The proton conductivity of oPBI/FeSPP(30wt%) and oPBI/FeSPP(30wt%)/GF(3wt%) membranes reached 0.089 and 0.074 S cm−1 at 180 °C and 100% relative humidity, respectively. At 180 °C, the proton conductivity of oPBI/FeSPP(30wt%) and oPBI/FeSPP(30wt%)/GF(3wt%) was 0.052 and 0.042 S cm−1 at 50% RH, respectively. oPBI/FeSPP(30wt%)/GF(3wt%) exhibited good selectivity of 3.84 × 105 S s cm−3 indicating good potential for applications in direct methanol fuel cells.
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•oPBI/ferric sulfophenyl phosphate (FeSPP)/glass fiber (GF) membrane was prepared.•Intense hydrogen bonding networks were constructed among oPBI, FeSPP and GF.•The H-bonds provided proton channels and reinforced the physicochemical properties.•Good proton conductivity was reached at different humidity at high temperature.
Objective. In this study, we explored the influence of single nucleotide polymorphism (SNP) in the noncoding region of intercellular adhesion molecule 1 (ICAM1) gene on the occurrence and metastasis ...of primary hepatocellular carcinoma (PHC). Methods. Sanger sequencing was used to analyze the genotypes of rs3093032, rs923366, and rs281437 locus in the 3′untranslated region (UTR) of the ICAM1 gene. The level of plasma ICAM1 was analyzed by enzyme-linked immunosorbent assay (ELISA). Results. After adjusting for risk factors such as BMI, smoking, drinking, family history of tumors, and hepatitis B virus test results, the CT genotype at rs3093032 of the ICAM1 gene (OR=0.19, 95% CI: 0.08-0.44, P<0.01), dominance model (OR=0.23, 95% CI: 0.11-0.48, P<0.01), and T allele (OR=0.27, 95% CI: 0.14-0.53, P<0.01) were related to the reduced risk of PHC susceptibility. rs923366 locus CT genotype (OR=0.63, 95% CI: 0.44-0.90, P=0.01), TT genotype (OR=0.23, 95% CI: 0.10-0.53, P<0.01), dominant model (OR=0.55, 95% CI: 0.39-0.77, P<0.01), recessive model (OR=0.28, 95% CI: 0.12-0.62, P<0.01), and T allele (OR=0.55, 95% CI: 0.42-0.73, P<0.01) were related to a reduction in the risk of PHC susceptibility. rs281437 locus CT genotype (OR=2.08, 95% CI: 1.40-3.09, P<0.01), TT genotype (OR=5.20, 95% CI: 2.22-12.17, P<0.01), dominant model (OR=2.45, 95% CI: 1.69-3.54, P<0.01), recessive model (OR=4.32, 95% CI: 1.86-10.06, P<0.01), and T allele (OR=2.46, 95% CI: 1.79-3.38, P<0.01) were significantly related to the increased risk of PHC susceptibility. SNPs at rs3093032, rs923366, and rs281437 of the ICAM1 gene were significantly correlated with TNM stage and tumor metastasis of PHC patients (P<0.05). Conclusion. SNPs at rs3093032, rs923366, and rs281437 in the 3′UTR region of the ICAM1 gene are related to the occurrence and metastasis of PHC.
Cyclic voltammetry (CV) and stripping voltammetry were used to study the electro-oxidation of dimethyl ether (DME) on powder microelectrodes (PMEs) containing Pt black and Pt–Ru black. As evidenced ...by current–time curves of DME oxidation, Pt–Ru was better than Pt in catalytic oxidation of DME, which is due to the high concentration of OH
ads species on its surface. Results also showed that high temperature not only promotes the oxidation of DME, but also increases the concentration of OH
ads species formed by water decomposition. In addition, the performance of single direct DME fuel cell was investigated combined with gas chromatographic (GC) analyses of its anode outlet stream. Based on CV tests, a mechanism of DME electro-oxidation was tentatively proposed, indicating two kinds of DME adsorption modes, Pt–CO and Pt–COH existed on Pt surface.
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•Closely packed amide polyphthalocyanine iron (CPMPcFe) is prepared by one step solid state method.•CPMPcFe molecule possesses a large π bond and doesn’t decompose below ...600 °C.•CPPPcFe/C has excellent activity, selectivity and durability towards oxygen reduction reaction.•The active center of CPMPcFe/C catalyst is FeN4 in the phthalocyanine ring.
It is crucial to design the inexpensive and highly efficient electrocatalysts for oxygen reduction reaction (ORR) for the future commercialization of fuel cell devices. Herein, a closely packed amide polyphthalocyanine iron (CPMPcFe) with two-dimensional planar structure supported by Vulcan XC-72 was firstly prepared, and then the precursor was sintered at 400 °C under an Ar flow to obtain the CPMPcFe/C (1:1) catalyst. The SEM and TEM images of the CPMPcFe/C catalysts confirmed that CPMPcFe was well distributed on the surface of Vulcan XC-72. X-ray photoelectron spectroscopy (XPS) further identified the active center of CPMPcFe/C (1:1, 400 °C) was FeN4 in the polyphthalocyanine ring. Electrochemically, CPMPcFe/C displays excellent oxygen reduction reaction electrocatalytical properties. Firstly, it showed a half-wave potential of 0.87 V, which was more positive than those of iron phthalocyanine/C (FePc/C, 0.71 V) and 6 wt% Pt/C (0.83 V). The oxygen reduction current loss of CPMPcFe/C after 5000-cycle cyclic voltammetry test was 0.05 mA cm−2, while that of FePc/C was 0.35 mA cm−2. Chronoamperometry tests showed that FePc/C exhibited a rapid decrease of the current density by about 28.2%, while there was only about 16.9% loss for the current density of CPMPcFe/C under the same operation.
The development of cost-effective electrocatalysts with high performance for oxygen reduction reaction is the main problem for fuel cells and metal–air batteries. Herein, a novel interconnected ...hierarchical three-dimensional graphene (3D-HG) is first fabricated by the templated method, where coal tar pitch and CaCO3 were used as carbon precursor and template, respectively. The pyrolysis of CaCO3 could produce CaO and CO2 at 800 °C, where the obtained CaO can serve as the template and CO2 can promote the formation of micropores to facilitate the interconnect of the mesopores in 3D-HG. Spinel NiCo2O4 is synthesized on 3D-HG by the hydrothermal method, which is denoted as NiCo2O4/3D-HG. The as-prepared NiCo2O4/3D-HG catalysts retain the hierarchical micro–mesoporous structure of graphene. Benefiting from the mass transport convenience of the hierarchical structure, NiCo2O4/3D-HG exhibits high-performance half-wave potential (0.82 V vs reversible hydrogen electrode (RHE)) better than NiCo2O4/reduced graphene oxide (0.79 V), NiCo2O4/carbon nanotubes (0.73 V), and 20 wt % Pt/C (0.81 V), and shows higher durability than 20 wt % Pt/C. This work proves that NiCo2O4/3D-HG is a cost-effective electrocatalyst for fuel cells or metal–air batteries.
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