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.
摘要：
A series of Cd1-xZnxS solid solutions and samples of amorphous MoS2 decorated on Cd1-xZnxS microspheres were successfully prepared. The crystal phases, morphologies, elemental distribution, chemical compositions, optical properties, and specific surface areas of the as-fabricated samples were investigated by the corresponding measurement techniques. The photocatalytic H-2 evolution activities of the MoS2/Cd1-xZnxS composites were explored and compared using lactic acid as a sacrificial reagent. The results manifested that 5 wt% MoS2 loaded on the surface of the Cd0.8Zn0.2S solid solution could attain the highest photocatalytic H-2 evolution rate of 12.39 mmol g(-1) h(-1), corresponding to an apparent quantum efficiency (AQE) of about 16.5% under 420 nm monochromatic light. The electrochemical impedance spectroscopy (EIS), transient photocurrent response and photoluminescence (PL) spectroscopy experiments confirmed that MoS2 as a cocatalyst could promote the transfer and separation of photogenerated charge carriers on the Cd0.8Zn0.2S solid solution. In addition, amorphous MoS2 decorated on the Cd0.8Zn0.2S sample showed a much better performance than that of crystalline MoS2. This could be because amorphous MoS2 possessed more abundant active sites than its crystalline counterpart. Based on the energy band positions of Cd0.8Zn0.2S and MoS2, a tentative mechanism for the enhanced photocatalytic H-2 evolution activity was proposed.
摘要：
To further improve the light response range and photocatalytic activity of Bi2SiO5, the Bi2SiO5/BiOBr type-Il heterojunction photocatalysts were constructed by in-situ partial ion exchange strategy using Bi2SiO5 as precursor. The crystal phases, morphologies, chemical compositions, optical properties and textural structures of as-synthesized Bi2SiO5/BiOBr photocatalysts were characterized by the corresponding analytical techniques. The photocatalytic activities of samples were evaluated by degrading Rhodamine B (RhB) solution under visible light irradiation. The results showed that the Bi2SiO5/BiOBr heterojunction photocatalysts significantly improved the photocatalytic performances, which would be ascribed to the extended light response, enhanced adsorption capacity, matched energy band structures and intimate interface contact. Construction of Bi2SiO5/BiOBr heterojunction facilitated the separation and transfer of photoexcited charge carriers, which were verified by the electrochemical impedance spectroscopy (EIS), transient photocurrent response and steady photoluminescence spectroscopy (PL) measurements. This work would offer a new insight into the design and preparation of Bi2SiO5-based heterojunction photocatalysts for the removal of organic contaminant. (C) 2019 Elsevier B.V. All rights reserved.
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：
TiO2-loaded Ti3C2 with small interlayer spacing [TiO2/Ti3C2(SIS)] was successfully synthesized through hydrothermal treatment and subsequent calcination under argon atmosphere. The phase composition, morphology and photophysical properties of Ti3C2, TiO2 and TiO2/Ti3C2(SIS) were investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FSEM), transmission electron microscopy (TEM), UV–Vis spectrophotometry and fluorescence spectrophotometer, respectively. Furthermore, the photocatalytic activities of Ti3C2, TiO2 and TiO2/Ti3C2(SIS) were measured through monitoring photodegradation of methylene blue (MB) under ultraviolet (UV) light irradiation. The results showed that TiO2/Ti3C2(SIS) had an interfacial heterojunction between TiO2 and Ti3C2 with small interlayer spacing, leading to obviously improved optical absorbability and light quantum efficiency. Furthermore, the results of photocatalytic experiment indicated that TiO2/Ti3C2(SIS) exhibited significantly improved photocataytic activity compared with Ti3C2 and TiO2.
摘要：
To avoid deficiencies of traditional electrocoagulation process, electrocoagulation process powered by renewable photovoltaic energy has been directly employed to remove Ni from wastewater. Results show that under the solar irradiation intensity (SII) of 750 - 30 W/sq m, Al electrode has higher Ni removal efficiency (NRE) than graphite and Ti and its NRE was almost 100% in 40 min. An optimum distance of 20 mm was determined for the electrode gap. NRE in 40 min almost decreased from 99.6% to 78.8% when initial Ni2+ concentration increased from 100 to 300 mg/L. Under the SII of 610 - 40 W/sq m, solution containing SO42- of 3.4 mmol/L got the highest NRE, while wastewater containing Cl- of 6.8 mmol/L had the lowest. Also, effluent, including SO42- of 1.7 and Cl- of 3.4 mmol/L, showed a higher NRE as well. NRE in 40 min increased when output power of the photovoltaic panel changed from 30 to 90 W, but did not show an obviously increasing tendency when the power improved further to 120 W.
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.
