Search

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Preparing AEMs with robust mechanical properties, high ionic conductivity and excellent chemical stability is challenging. Here, cross-linked/aggregated AEMs are prepared by incorporating hydrophilic Jeffamine cross-linkers and hydrophobic side chains into the rigid quaternized poly (vinyl benzyl chloride). Jeffamine's flexibility ensures high elongation at break of the cross-linked/aggregated membranes (125.0–199.8%). The hydrophobic side chain limits excessive water absorption and facilitates self-aggregation of hydrophilic and hydrophobic domains, enhancing tensile strength (5.08–7.40 Mpa in wet state) and improving ionic conductivity of the AEMs (73.8–110.4 mS cm−1 at 80 °C). Alkali-resistant PVB, restricted dimensionality, and ordered micro-phase separation morphology contribute to outstanding chemical stability of the AEMs. Degradation of both backbones and cations is <20% after treatment in 1 M NaOH solution at 80 °C for 30 days. Based on the membrane, a peak power density of 354.4 mW cm−2 at 60 °C is yielded. PVB based AEMs of c (Je) a Cx-QAPVB exhibit excellent flexibility, outstanding alkali-resistant and high hydroxide ion conductivity. [Display omitted] • Highly flexible and transparent poly (vinyl benzyl chloride) based anion exchange membranes are prepared. • Anion exchange membranes exhibit improved ionic conductivity and robust stability. • A peak power density of 354.4 mW cm−2 is presented. [ABSTRACT FROM AUTHOR]

AuCo alloys were prepared by magnetron sputtering for the first time without considering the insolubility on the phase diagram. The electronic effect between Au and Co can change the oxygen adsorption energy and the ORR activity. The ORR activity of the Au46Co54 alloy electrode not only exceeded that of Au, but also exceeded that of Pt in basic solution. [ABSTRACT FROM AUTHOR]

Electrolyzing water is an environmentally friendly and renewable way to obtain high purity hydrogen. Ruthenium has strong water dissociation ability and suitable hydrogen adsorption energy, so it is considered as one of the candidates of excellent electrocatalysts for hydrogen evolution in alkaline solution. The dynamic hydrogen bubble template (DHBT) is a good electrodeposition technology, which can obtain the 3D metal foams. However, as far as we know, there is no report on the preparation of Ru electrocatalyst by the DBHT method. In this work, the trumpet-shaped Ru on amorphous cobalt support (T-Ru/a-Co) is prepared by the DHBT electrodeposition for the first time. The defect locations are uniformly distributed on the surface of amorphous cobalt (a-Co), which can effectively lead to the formation of nano-bubble template in the DHBT process. However, this special morphology cannot be obtained on the surface of crystalline Co (c-Co). In addition, the electronic structure of T-Ru/a-Co has also been obviously modified, in which the proportion of Ru4+/Ru0 in T-Ru/a-Co has increased, accompanied by the change of binding energy of Ru. It only needs an overpotential of 49 mV to obtain a current density of 10 mA cm−2 for the T-Ru/a-Co. The specific activity (SA), turnover frequency (TOF) and mass activity (MA) of T-Ru/a-Co are 0.23 mA cm−2, 0.48 s−1 and 0.24 A mg−1, which are both higher than those of Pt/C, the disk-shaped Ru on the c-Co support (D-Ru/c-Co) and Ru/C, respectively. • The trumpet-shaped Ru is prepared by the dynamic hydrogen bubble template (DHBT) electrodeposition for the first time. • The amorphous Co can form nano-bubble template in DHBT process, but it can't be realized on the surface of crystalline Co. • The electronic structure of trumpet-shaped Ru has also been obviously modified. • The specific activity, turnover frequency and mass activity of trumpet-shaped Ru are both higher than those of Pt/C. [ABSTRACT FROM AUTHOR]

Nano-network Ru with definite lattice defects on amorphous Co nanosheets is obtained for the first time. Amorphous Co support can promote the surface Ru to obtain special morphology and modified electronic structure, thus improving HER activity in alkaline solution. A current density of 10 mA cm−2 can be obtained only with an overpotential of 33.5 mV. [ABSTRACT FROM AUTHOR]

• The CuO/RuO 2 electrode was prepared by the two-step thermal decomposition method for the first time. • Compared with the ordinary RuO 2 electrode, the selectivity of CER of CuO/RuO 2 electrode is remarkably improved. • During the preparation of AEW, the HClO content of AEW2 (prepared by CuO/RuO 2) is 2.5 times that of AEW1 (prepared by RuO 2). • In the sterilization experiments on E. coli and B. subtilis , the germicidal efficacy of AEW2 is obviously superior to that of AEW1. Electrochemical chlorine evolution reaction (CER) is one of the most important practical applications of electrochemical reaction, which can be used for electrochemical disinfection. The electrochemical disinfectant of acidic electrolyzed water (AEW) is obtained by electrolyzing extremely dilute chlorine-containing solution in ion-exchange membrane electrolyzer. In the anode area, HClO is produced by CER, which has a strong bactericidal effect. Due to the low concentration of chloride ion, it is necessary to improve the CER selectivity of the electrode in order to improve the efficiency of chlorine electrolysis. In this paper, CuO/RuO 2 electrode was prepared by the two-step thermal decomposition method, and the surface morphology and electronic structure of RuO 2 electrode were modified. Compared with the ordinary RuO 2 electrode, the CER activity of CuO/RuO 2 electrode is improved. For the oxygen evolution reaction (OER), the activity of CuO/RuO 2 electrode is significantly lower than that of RuO 2 electrode. The CER mechanism of CuO/RuO 2 electrode is the second electron transfer, and the OER mechanism is the formation and transformation of OH ads. The potential difference between CER and OER of CuO/RuO 2 -3 electrode is 105 mV, which is 52 mV higher than that of RuO 2 electrode, so the selectivity of CER of CuO/RuO 2 electrode is remarkably improved. During the preparation of AEW, the HClO of AEW2 (prepared by CuO/RuO 2 -3 electrode) is 0.72 mmol/L, which is 2.5 times that of AEW1 (prepared by RuO 2 electrode). In the sterilization experiments on E. coli and B. subtilis , the germicidal efficacy of AEW2 (3.71 and 2.99 log 10 CFU/mL) is obviously superior to that of AEW1 (0.76 and 0.61 log 10 CFU/mL). [ABSTRACT FROM AUTHOR]

RuCo-ANFs with different proportions can be successfully prepared by magnetron sputtering, and their lattice constants can be adjusted accurately. In the RuCo-ANF, there is an obvious electronic interaction between Ru and Co, thus adjusting the ΔGH* on its surface. There is a volcanic relationship between the HER activity and the lattice constant of RuCo-ANF. [ABSTRACT FROM AUTHOR]

AuIr alloy nanoparticles were successfully prepared without using surfactants for the first time despite Au and Ir being immiscible according to phase diagrams. The lattice parameters of the AuIr alloy can be adjusted arbitrarily. The oxygen reduction reaction (ORR) activity of Au5Ir5 alloy is better than that of Au or Ir, and the oxygen evolution reaction (OER) activity of the Au5Ir5 alloy is as good as that of Ir in alkaline solution. [ABSTRACT FROM AUTHOR]

An obvious H-UPD for a nano AuTiO2−x composite has been found for the first time in terms of the electrochemical characteristics of the Au composite. The electronic effect between Au and TiO2 and the oxygen vacancy defect would change the adsorption energy of H and HER activity. The HER activity of the AuTiO2−x electrode is 6.44 times that of the Au electrode. [ABSTRACT FROM AUTHOR]

Abstract 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 TiO 2 doped IrO 2 -Ta 2 O 5 (IrO 2 -Ta 2 O 5 -TiO 2) 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 IrO 2 -Ta 2 O 5 -TiO 2 electrode. The electrochemical behaviors and actives of the IrO 2 -Ta 2 O 5 -TiO 2 electrode coupled with the IrO 2 -Ta 2 O 5 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 IrO 2 -Ta 2 O 5 -TiO 2 electrode was also discussed in this article. Graphical abstract Unlabelled Image Highlights • Electrolyzed oxidizing water was efficiently prepared by TiO 2 doped IrO 2 -Ta 2 O 5 electrode. • TiO 2 doped IrO 2 -Ta 2 O 5 electrode has very excellent chloride evolution reaction selectivity. • TiO 2 doped IrO 2 -Ta 2 O 5 electrode has a long accelerated service lifetime. [ABSTRACT FROM AUTHOR]

The research and development of high-efficiency low-temperature disinfection technology in all aspects of cold-chain food has begun to receive attention. This paper aims to develop low temperature acidic electrolyzed water (LT-AEW) disinfectant. The anti-freezing temperature, disinfection efficiency and practical application effect were evaluated in detail. The results had shown that the freezing point of AEW can be reduced to −18 °C by adding 25% CaCl 2 , 20% NaCl, 30% ethylene glycol (EG) and 35% propylene glycol (PG). At the low temperature (−1, −10 and −18 °C), the bactericidal efficiencies of all EG-acidic electrolyzed waters (EG-AEWs) with different EG contents were close. The reason is that although the low temperature environment will reduce the sterilization efficiency of EG-AEW, the addition of EG can promote the increase of HClO content in EG-AEW, thus increasing the sterilization efficiency. As long as the HClO content reached 35.2, 50.8 and 64.3 mg L−1, the killing logarithm (KL) value had achieved 4.50, 4.49 and 5.07 log 10 (CFU mL−1). Finally, the KL values of EG-AEW against Escherichia coli on the corrugated board and stainless-steel board both exceeded 3 log 10 (CFU mL−1) at the low temperature, which indicates that EG-AEW can be applied in food cold chain. • A low temperature acidic electrolyzed water (LT-AEW) is studied for the first time. • The freezing point of ethylene glycol AEW (EG-AEW) can reach to −18 °C. • The killing logarithm of EG-AEW against E. coli is 5.07 log 10 (CFU mL−1) at −18 °C. • EG-AEW can effectively sterilize E. coli on corrugated and stainless-steel board. [ABSTRACT FROM AUTHOR]

Phosphorus doped graphitic carbon nitride (g-C 3 N 4 ) was easily synthesized using ammonium hexafluorophosphate (NH 4 PF 6 ) as phosphorus source, and ammonium thiocyanate (NH 4 SCN) as g-C 3 N 4 precursor, through a direct thermal co-polycondensation procedure. The obtained phosphorus doped g-C 3 N 4 was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectra (FTIR), UV–vis diffuse reflectance absorption spectra (UV-DRS), photoelectrochemical measurement and photoluminescence spectra (PL). The photocatalytic activities of phosphorus doped g-C 3 N 4 samples were evaluated by degradation of Rhodamine B (RhB) solution under visible light irradiation. The results showed that the phosphorus doped g-C 3 N 4 had a superior photocatalytic activity than that of pristine g-C 3 N 4 , attributing to the phosphorus atoms substituting carbon atoms of g-C 3 N 4 frameworks to result in light harvesting enhancement and delocalized π-conjugated system of this copolymer, beneficial for the increase of photocatalytic performance. The photoelectrochemical measurements also verified that the charge carrier separation efficiency was promoted by phosphorus doping g-C 3 N 4 . Moreover, the tests of radical scavengers demonstrated that the holes (h + ) and superoxide radicals ( O 2 − ) were the main active species for the degradation of RhB. [ABSTRACT FROM AUTHOR]

Abstract: Ball-in-ball CuSCN hollow architecture is successfully synthesized by a facile one-pot aqueous solution method in the presence of poly(vinylpyrrolidone) at room temperature. The as-synthesized products are characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance absorption spectra (DRS) and nitrogen adsorption–desorption measurement. A possible formation mechanism for CuSCN hollow spheres by the difference of solubility products (K sp) of CuBr and CuSCN or chemical self-transformation is proposed based on the experimental observations. The band gap energy of hollow CuSCN sphere is estimated to be 3.77eV based on the results of optical measurement. The BET specific surface area of ball-in-ball CuSCN hollow architecture is calculated to be 30.5m2/g and it has a bimodal mesoporous structure from nitrogen adsorption–desorption investigation. [Copyright &y& Elsevier]

Abstract: In this paper, dynamic mechanical analysis (DMA), dielectric spectroscopy (DS) and positron annihilation lifetime spectroscopy (PALS) were used to study chlorinated butyl rubber (CIIR), in order to shed light on its unique relaxation behaviors. The dynamic mechanical loss tangent of CIIR reveals an asymmetrical broad structure with a maximum peak on the high-temperature side and a shoulder peak on the low-temperature side. DS clarifies that the shoulder peak, which exactly corresponds to the ɛ″ peak, is the α process originating from the local segmental motion. While the maximum peak is assigned to the slow process arising from the motion of longer chain segments. The slow process exhibits stronger frequency dependence than the α process. The PALS analysis also shows the two processes; moreover, it suggests that CIIR exhibits very effective chain packing. It is due to the effective chain packing that the motion of longer chain segments is retarded and separates from the local segmental motion in time scale. This effect is another reason for the two-peak structure of CIIR, besides the low intermolecular co-operativity. [Copyright &y& Elsevier]

In order to investigate the relationship between the side chain topology of comb-shaped anion exchange membranes (AEMs) and membranes properties, two types of hydrophobic side chains attached AEMs that based on QAPPO are synthesized, namely side chains grafted onto backbones and side chains tethered to cations, resulting in A x SB -QAPPO and A x SC -QAPPO AEMs, respectively. Compared with A x SC -QAPPO, the side chains in A x SB -QAPPO AEMs are more inclined to facilitate the membranes to form broad and interconnected ion channels, promoting ion conduction and providing more free volume for the external water to enter the membranes, which are benefit to improving the ionic conductivity and chemical stability of the A x SB -QAPPO samples. At 80 °C, the OH− conductivity of A 8 SB -QAPPO is 101.2 mS cm−1, while the values for A 8 SC -QAPPO and QAPPO are only 56.1 and 48.5 mS cm−1 respectively. After the stability test, the weight and IC retentions of A 8 SB -QAPPO are 83.0% and 77.0%, respectively, while the values for A 8 SC -QAPPO are 76.5% and 68.0%, respectively, and the values for QAPPO are 56.0% and 42.0%, respectively. Besides, the influence of side chain length on the membranes properties is studied. The chemical stability for both A x SB -QAPPO and A x SC -QAPPO AEMs is enhanced by increasing the side chain length from 5 to 14. After the stability test, the IEC retentions of A 5 SB -QAPPO, A 8 SB -QAPPO, A 14 SB -QAPPO, A 5 SC -QAPPO, A 8 SC -QAPPO and A 14 SC -QAPPO are 60.0%, 78.0%, 90.0%, 49.0%, 70.0% and 75.0%, respectively. While for ionic conductivity, the AEMs with the side chain length of 8 exhibit the highest OH− conductivity. Hence, we speculate that the comb-shaped AEMs with hydrophobic side chains attached to backbones (A x SB -QAPPO) are superior to the membranes with the side chains linked to cations (A x SC -QAPPO), and the membranes performance can be further optimized by adjusting the side chain length. [Display omitted] • SC -type AEMs (A x SC -QAPPO) and SB- type AEMs (A x SB -QAPPO) with different length of side chain that based on QAPPO were synthesized successfully. • An important insight into the relationship between the side chain topology of comb-shaped AEMs and membranes properties was offered. • A x SB -QAPPO samples showed higher ionic conductivity and chemical stability than those of (A x SC -QAPPO) AEMs. [ABSTRACT FROM AUTHOR]

With the demand of renewable hydrogen energy, electrocatalytic water splitting is considered as the most promising method for hydrogen production. Herein, a simple synthesis of the nanoporous RuO 2 (NP-RuO 2) characterized by RuO(OH) 2 surface phase was reported. The physical characterization of the materials are achieved by transmission electron microscope (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray fluorescence (XRF) and X-ray photoelectron spectrometer (XPS). For HER activity, the NP-RuO 2 –450 electrode only needs 87 mV overpotential to obtain a current density of 10 mA cm−2, while RuO 2 generates the same current density at a relatively large overpotential (η = 142 mV). Notably, the HER activity of NP-RuO 2 –450 is also higher than that of Pt (10 mA cm−2, η = 103 mV). The specific activity of NP-RuO 2 –450 is still 2.4 times higher than that of RuO 2 reflecting the enhancement of the intrinsic activity. The OER activity of NP-RuO 2 –450 electrode has outperformed that of RuO 2. The apparent activity of NP-RuO 2 –450 is 3.5 times that of RuO 2 at an overpotential of 270 mV. For the specific activity, NP-RuO 2 –450 is still 1.9 times higher than that of RuO 2. Therefore, NP-RuO 2 –450 electrode could be used as a bifunctional catalyst for overall water splitting. The excellent HER and OER activities of the NP-RuO 2 –450 electrode could be attributed to the enhancement of electrochemical surface area of electrode material. However, the more important reason is that the new surface phase creation of hydroxides and the electronic structure modification of Ru. Unlabelled Image • A simple synthesis of the nanoporous RuO 2 (NP-RuO 2) characterized by RuO(OH) 2 surface phase was reported. • NP-RuO 2 electrode can be used as a bifunctional catalyst for overall water splitting for its good HER and OER activities. • The good activity of NP-RuO 2 electrode is attributed to the hydroxide formation and electronic structure modification. [ABSTRACT FROM AUTHOR]

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, ac S 6 QAPSF, ac S 8 QAPSF and ac S 10 QAPSF. Cross-linked network shoulders the responsibility to toughen the ac S x QAPSF. Appropriate micro-morphology is responsible for facilitating the conduction of OH− and improving the alkaline stability of the ac S x QAPSF. Compared with the original QAPSF, ac S x QAPSF membranes exhibit much better properties. Specifically, for ac S 8 QAPSF, a high OH− conductivity of 90.5 mS cm−1 is achieved at 80 °C, with the swelling degree of 10.0%. The tensile strength and elongation at break of wet ac S 8 QAPSF at 25 °C are 23.9 Mpa and 21.1%, respectively. After testing in 1 M NaOH at 80 °C for 30 days, the weight loss of ac S 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 ac S 8 QAPSF, a fuel cell peak power density of 0.612 W cm−2 is obtained at 60 °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. The unique ac S x QAPSF membrane can alleviate the tradeoff among ionic conductivity, mechanical strength and chemical stability. Image 1 • Novel aggregated and ionic cross-linked AEMs based on PSF are synthesized. • An important insight into the design of AEMs with high performance is provided. • The fuel cell of ac S 8 QAPSF achieved a peak power density of 612 mW cm−2 at 60 °C. [ABSTRACT FROM AUTHOR]

Hydrogen is an important renewable energy source. Electrochemical decomposition of water for hydrogen production has attracted more and more attention as an appealing hydrogen production strategy. Previous studies have proved that controlling the morphology of Ru can improve hydrogen evolution reaction (HER) activity. Therefore, the preparation of ordered spherical ruthenium nanocatalysts by hydrothermal method (Ru-HT) is described in this paper. The morphology, crystal structure and electronic state of Ru-HT were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). At the same time, the electrochemical properties and surface charge were studied and analyzed by cyclic voltammetry (CV) characterization and electrochemical impedance spectroscopy (EIS). The experimental results have demonstrated that the HER activity of Ru-HT is obviously better than that of Ru by liquid phase reduction method (Ru-LR). When HER current density reaches 10 mA cm−2, the overpotential of Ru-LR electrocatalyst is 88.8 mV, while the overpotential of Ru-HT electrocatalyst is reduced to 55.7 mV in acidic medium. The Tafel slope of Ru-HT is only 36.5 mV dec−1 and the exchange current density is 0.44 mA cm−2, which indicates the rate determining step of the HER process should be the electrochemical desorption step (Heyrovsky step). By adjusting hydrothermal time and hydrothermal temperature, HER activity was further optimized. During the optimization process, the preparation conditions would change the hydrogen adsorption intensity on Ru surface to some extent. The adsorption strength of Ru H, together with the electrochemical surface area, will affect the HER activity of Ru. Unlabelled Image • The HER activity of Ru-HT is obviously better than that of Ru-LR. • The rate determining step of the HER process for Ru-HT should be the electrochemical desorption step. • The adsorption strength of Ru-H will affect the HER activity of Ru-HT together with the ESA. [ABSTRACT FROM AUTHOR]