摘要：
In order to achieve a better trade-off among ionic conductivity, mechanical strength and chemical stability, a series of novel aggregated and ionic cross-linked anion exchange membranes (AEMs) are recommended, namely, acS(6)QAPSF, acS(8)QAPSF and acS(10)QAPSF. Cross-linked network shoulders the responsibility to toughen the acS(x)QAPSF. Appropriate micro-morphology is responsible for facilitating the conduction of OH- and improving the alkaline stability of the acS(x)QAPSF. Compared with the original QAPSF, acS(x)QAPSF membranes exhibit much better properties. Specifically, for acS(8)QAPSF, a high OH- conductivity of 90.5 mS cm(-1) is achieved at 80 degrees C, with the swelling degree of 10.0%. The tensile strength and elongation at break of wet acS(8)QAPSF at 25 degrees C are 23.9 Mpa and 21.1%, respectively. After testing in 1 M NaOH at 80 degrees C for 30 days, the weight loss of acS(8)QAPSF is 8.0%, with the losses of tensile strength and elongation at break of 13.8% and 13.3%, respectively. Its IEC and IC retentions are 92.0% and 90.5%, respectively. For acS(8)QAPSF, a fuel cell peak power density of 0.612 W cm(-2) is obtained at 60 degrees C. While for QAPSF, its fuel cell peak power density is only 0.101 W cm(-2), and the film is cracked after the 30 days stability test.
摘要：
Chlorine evolution reaction (CER) is a very important electrochemical reaction process in modern electrochemical industry. To develop an efficient CER electrode, not only the active components but also the morphology of the electrode should be considered. In this work, the ordered spherical Ru-RuO2 electrode was prepared by hydrothermal reaction for improving the CER activity. X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and X-ray diffraction (XRD) characterizations were employed to analyze the electrode structures. Compared with RuO2 electrode prepared by Adams method, the CER activity of Ru-RuO2 electrode is obviously improved. The improvement of activity should be attributed to the change of electronic structure and the ordered structure of electrode surface. The prepared Ru-RuO2 particles are spherical and evenly distributed, thus showing an orderly morphology. Such an unified structure can be conducive to the diffusion of Cl-2. The diffraction peak of (101) crystal plane of Ru-RuO2 electrode has slightly positive shifted of 0.4 degrees. It indicates that the lattice of RuO2 on the outside surface of Ru-RuO2 has been compressed to a certain extent, which may reduce the adsorption energy of Cl and accelerate the rate of chlorine desorption process.
摘要：
Electrolyzed oxidizing water (EO water) is a new disinfectant, which has been proved to possess the high bactericidal efficiency against a wide variety of microorganisms ranging from bacteria to viruses. EO water is generated by electrolysis of an extremely dilute NaCl solution. Therefore, it is necessary to enhance the selectivity of chlorine evolution reaction (CER), which the oxygen evolution side reaction (OER) needs to be minimized. In the present study, the TiO2 doped IrO2-Ta2O5 (IrO2-Ta2O5-TiO2) electrode was prepared by the thermal decomposition method. X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray fluorescence (XRF) characterizations were employed to study the performances the IrO2-Ta2O5-TiO2 electrode. The electrochemical behaviors and actives of the IrO2-Ta2O5-TiO2 electrode coupled with the IrO2-Ta2O5 electrode was investigated using cyclic voltammetry (CV) and linear sweep voltammetry (LSV). Furthermore, the selectivity of CER was analyzed through the potential difference between the CER and OER at a constant current density to illustrate the discrepancy in available chlorine content (ACC) of two kinds of oxide electrodes in the EO water preparation. In addition, the accelerated service lifetime of the IrO2-Ta2O5-TiO2 electrode was also discussed in this article.
摘要：
With increasing demands for clean and renewable energy, electrocatalytic water splitting is considered as the most promising procedure of hydrogen production. Pt is the best catalyst for the hydrogen evolution reaction (HER). However, the low oxygen evolution reaction (OER) activity of Pt prevents it from becoming a bifunctional catalyst in practical application. Ir-based electrocatalysts with good OER activities are expected to become the most promising bifunctional catalysts once their HER activities are improved. Herein, we report a simple synthesis of a Si-doped Ir electrode using magnetron sputtering. The physical and electrochemical characterization of the materials is achieved by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray fluorescence (XRF), X-ray diffraction (XRD) and X-ray photoelectron spectrometry (XPS). The electrochemical catalytic activity of the Si-doped Ir electrode toward the HER is demonstrated for the first time. Cyclic voltammetry (CV) curves reveal that the addition of Si can improve the utilization rate of Ir and result in a large electrochemical surface area (ESA). The overpotential of the Si-doped Ir electrode for the HER (eta = 114 mV, 50 mA cm(-2)) is obviously lower than that of an Ir electrode (eta = 148 mV, 50 mA cm(-2)) and very close to that of a Pt electrode (eta = 106 mV, 50 mA cm(-2)). The mass specific activity of the Si-doped Ir electrode exceeds that of an Ir electrode by a factor of ca. 2 at an overpotential of eta = 200 mV. The superior HER activity of the Si-doped Ir electrode could be attributed to the electronic structure modification of Ir by the interaction effect with Si as studied through XPS analysis. Moreover, the Tafel slope of 36.5 mV dec(-1) suggests that the mechanism for the Si-doped Ir electrode-catalyzed HER is Volmer-Tafel, in which the recombination of two adsorbed hydrogen atoms is the rate-determining step. In addition, the OER activity of the Si-doped Ir electrode outperforms that of an Ir electrode, which enables the Si-doped Ir electrode to be used as a bifunctional catalyst for overall water electrolysis.
关键词：
MoS2 cocatalysts;Photocatalytic H-2 evolution;Charge transfer and separation
摘要：
The MoS2/ZnIn2S4 composites with MoS2 anchored on the surface of ZnIn2S4 microspheres were fabricated by a facile solvothermal method. To clarify the crystal phases, morphologies, chemical compositions, optical properties, and special surface areas of the obtained photocatalysts, the corresponding characterization measurements were performed. The photocatalytic H-2 evolution activities of MoS2/ZnIn2S4 composites were evaluated and compared with using lactic acid as sacrificial reagents. The results showed that integrating MoS2 with ZnIn2S4 could remarkably boost the photocatalytic H-2 evolution performance and the maximum H-2 evolution rate of 201 mu mol h(-1) was achieved over 1 wt% MoS2 loading on the ZnIn2S4, corresponding to the apparent quantum efficiency (AQE) about 3.08% at 420 nm monochromatic light. The photoelectrochemical tests and photoluminescence spectra (PL) versified that the efficient charge transfer and separation were achieved over MoS2/ZnIn2S4 composite in contrast with single ZnIn2S4, which would significantly benefit the enhancement of photocatalytic H-2 activity. This work provides a desired strategy to design and synthesize the visible-light-response photocatalysts with MoS2 as cocatalysts to enhance the photocatalytic activity. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
摘要：
Electrolyzed oxidizing water (EO water) bactericide is an indirect electrochemical sterilization technology, which is characterized by broad-spectrum, rapid and powerful sterilization. EO water, with a certain amount of available chlorine content (ACC), is generated by electrolysis of an extremely dilute NaCl solution. It is very important to study the preparation process of EO water, including electrode material and electrolytic process. In this paper, the effect of electrode material (platinum, iridium or ruthenium) on the physical and chemical parameters of EO water was investigated first. The effect of electrode composition and roasting temperature on the ACC of EO water was rigorously analyzed. The sterilization effect of EO water produced by different electrode materials was further discussed. In addition, the accelerated service lifetime of the electrode and exchange electrode polarity electrolysis were also investigated. Next, for the electrolysis process, the effects of ion exchange membrane type, current density and electrolyte concentration on the ACC of EO water, anode current efficiency and energy consumption were also studied. Finally, the stability of EO water, that is, the influence of illumination, heating and stirring on the physical and chemical parameters of EO water, was also observed in detail.
摘要：
The development of highly active and long-term stable electrocatalysts for the hydrogen evolution reaction (HER) is very important. Because of the hysteresis phenomenon, IrO2 is rarely used as a cathode material for the HER. Herein, an IrO2-TiO2 composite oxide was prepared using the thermal decomposition method. The physical and electrochemical characterization of the materials was achieved by scanning electron microscopy (SEM), X-ray fluorescence (XRF), X-ray diffraction (XRD), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). In the process of the HER, the current of IrO2 is only 1.91 mA cm(-2)@-0.2 V in the first segment scan. However, at the 51, 101 and 151 segment scan, the HER current increases to 6.85, 15.7 and 18.2 mA cm(-2)@-0.2 V, respectively. During the activation process of IrO2, the HER current has increased ten times. Compared with the HER activity of IrO2, there is almost no hysteresis for the IrO2-TiO2 electrode. In the first segment scan, the HER current has already reached 27.9 mA cm(-2)@-0.2 V and further increased to 31.1, 33.1 and 35.0 mA cm(-2) at the 51, 101 and 151 segment scan. The difference between them is not significant, which means that the IrO2-TiO2 electrode does not need activation. The IrO2-TiO2 electrode has exhibited a higher HER activity than the IrO2 electrode, which may be attributed to the electronic structure modification and the increase of the electrochemical area.
摘要：
MoS_2/ZnIn_2S_4 composites with MoS_2 anchored on the surface of ZnIn_2S_4 microspheres were synthesized by a two-step hydrothermal process. The obtained samples were characterized by X-ray diffraction, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, ultraviolet–visible diffuse reflectance absorption spectroscopy, nitrogen adsorption– desorption measurements, photoluminescence spectroscopy, and photoelectrochemical tests. The influence of the loading of MoS_2 on the photocatalytic H_2 evolution activity was investigated using lactic acid as a sacrificial reagent. A H_2 evolution rate of 343 μmol/h was achieved under visible light irradiation over the 1 wt% MoS_2/ZnIn_2S_4 composite, corresponding to an apparent quantum efficiency of about 3.85% at 420 nm monochromatic light. The marked improvement of the photocatalytic H_2 evolution activity compared with ZnIn_2S_4 can be ascribed to efficient transfer and separation of photogenerated charge carriers and facilitation of the photocatalytic H_2 evolution reaction at the MoS_2 active sites.
