Promoting effect of amorphous support on ruthenium-based catalyst for electrochemical hydrogen evolution reaction.

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.

Preparation of Acidic Electrolyzed Water by a RuO2@TiO2 Electrode with High Selectivity for Chlorine Evolution and Its Sterilization Effect.

The food hygiene problems caused by bacterial biofilms in food processing equipment are directly related to human life safety and health. Therefore, it is of great strategic significance to study new food sterilization technology. An acidic electrolyzed water (AEW) disinfectant is an electrochemical sterilization technology which has the characteristics of wide adaptability, high efficiency, and environmental friendliness. However, since the sterilization efficiency of AEW for biofilms is not ideal, it is necessary to increase the available chlorine content (ACC) in AEW. A feasible method to increase the ACC is by increasing the chlorine evolution reaction (CER) selectivity of the electrode for AEW preparation. In this paper, the RuO2@TiO2 electrode was prepared by thermal decomposition combined with high-vacuum magnetron sputtering. Compared with the oxygen evolution reaction (OER) activity of an ordinary RuO2 electrode, the OER activity of the RuO2@TiO2 electrode is significantly reduced. However, the CER activity of the RuO2@TiO2 electrode is close to the OER activity of RuO2. The CER mechanism of the RuO2@TiO2 electrode is the second electron transfer, and the OER mechanism is the formation and transformation of OHads. The potential difference between the CER and OER of the RuO2@TiO2 electrode is 174 mV, which is 65 mV higher than that of the RuO2 electrode, so the selectivity of the CER of the RuO2@TiO2 electrode is remarkably improved. During the preparation of AEW, the ACC obtained with the RuO2@TiO2 electrode is 1.7 times that obtained with the RuO2 electrode. In the sterilization experiments on Escherichia coli and Bacillus subtilis biofilms, the logarithmic killing values of AEW prepared the by RuO2@TiO2 electrode are higher than those of AEW prepared by the RuO2 electrode.

The volcanic relationship between the HER activity and lattice constant of RuCo alloy nanofilms.

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.

Plasma-Activated Acidic Electrolyzed Water: A New Food Disinfectant for Bacterial Suspension and Biofilm.

Food-borne diseases are widespread all over the world, and food safety has attracted much attention. This study is the first to use plasma to activate acidic electrolyzed water (AEW) to obtain a new disinfectant for food processing. The germicidal efficacy of plasma-activated acidic electrolyzed water (PA-AEW) on B. subtilis suspension and biofilm was investigated. Furthermore, the synergistic effect of different bactericidal factors was inferred by investigating the physicochemical parameters of PA-AEW and the influencing factors of bactericidal effect. The results demonstrate that PA-AEW is a highly effective and rapid disinfectant. The killing logarithm (KL) value of PA-AEW on B. subtilis suspension could reach 2.33 log10CFU/mL with a sterilization time of 10 s, which is significantly higher than that of AEW (KL = 0.58 log10CFU/mL) and plasma-activated water (PAW) (KL = 0.98 log10CFU/mL) (significant difference, p < 0.01). Moreover, the KL value of the B. subtilis biofilm of PA-AEW was 2.41 log10CFU/mL, better than that of PAW and AEW (significant difference, p < 0.01), indicating that PA-AEW has important application prospects in food processing. The synergistic effect should come from the interaction between reactive chlorine species (RCS) and reactive oxygen and nitrogen species (RONS) in PA-AEW.

A novel bifunctional catalyst for overall water electrolysis: nano IrxMn(1-x)Oy hybrids with L12-IrMn3 phase.

A nano IrxMn(1-x)Oy hybrid electrode with a L12-IrMn3 phase was used as a bifunctional catalyst with ultra-low iridium loading for overall water electrolysis in an acid solution for the first time. The HER activity of the IrxMn(1-x)Oy hybrid electrode not only exceeded that of IrO2, but also exceeded that of Pt/C. The OER activity of the IrxMn(1-x)Oy hybrid electrode also exceeded that of IrO2.

Nanostructured RuO2-Co3O4@RuCo-EO with low Ru loading as a high-efficiency electrochemical oxygen evolution catalyst.

Electrochemical water splitting technology is considered to be the most reliable method for converting renewable energy such as wind and solar energy into hydrogen. Here, a nanostructured RuO2/Co3O4-RuCo-EO electrode is designed via magnetron sputtering combined with electrochemical oxidation for the oxygen evolution reaction (OER) in an alkaline medium. The optimized RuO2/Co3O4-RuCo-EO electrode with a Ru loading of 0.064 mg cm-2 exhibits excellent electrocatalytic performance with a low overpotential of 220 mV at the current density of 10 mA cm-2 and a low Tafel slope of 59.9 mV dec-1 for the OER. Compared with RuO2 prepared by thermal decomposition, its overpotential is reduced by 82 mV. Meanwhile, compared with RuO2 prepared by magnetron sputtering, the overpotential is also reduced by 74 mV. Furthermore, compared with the RuO2/Ru with core-shell structure (η = 244 mV), the overpotential is still decreased by 24 mV. Therefore, the RuO2/Co3O4-RuCo-EO electrode has excellent OER activity. There are two reasons for the improvement of the OER activity. On the one hand, the core-shell structure is conducive to electron transport, and on the other hand, the addition of Co adjusts the electronic structure of Ru.

AuIr alloy with arbitrarily adjustable lattice parameters as a highly efficient electrocatalyst for the oxygen reduction reaction.

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.

A nano AuTiO2-x composite with electrochemical characteristics of under-potential deposition of H (H-UPD) as a highly efficient electrocatalyst for hydrogen evolution.

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.

Effect of platinum electrode materials and electrolysis processes on the preparation of acidic electrolyzed oxidizing water and slightly acidic electrolyzed water.

Electrolyzed oxidizing water (EOW) can be divided into acidic electrolyzed oxidizing water (AEOW) and slightly acidic electrolyzed water (SAEW). AEOW has the characteristics of low pH (pH < 2.7) and high oxidation-reduction potential (ORP > 1100 mV). SAEW is slightly acidic (pH = 5-6) and has an ORP of 700-900 mV. AEOW and SAEW both have a certain amount of active chlorine content (ACC), so they have the characteristics of broad spectrum, rapidity and high efficiency of sterilization. At present, there is little systematic research on AEOW and SAEW preparation. However, it is very important to study the preparation process, including electrode material and electrolytic process. First, the effects of Pt electrodes with different thermal decomposition temperatures on AEOW's pH, ORP and ACC values were investigated in detail. Next, for the SAEW preparation, the process is based on the preparation of AEOW by ion-exchange membrane electrolysis, reasonably mixing the electrolyzed cathode and anode solution. The effects of technological conditions such as electrolysis time, current density and electrolyte concentration have been systematically studied, and it is expected to get SAEW with a pH value slightly less than 7, a higher ORP value and a certain amount of ACC.

Effect of surface decoration of CNTs on the interfacial interaction and microstructure of epoxy/MWNT nanocomposites.

Epoxy resin nanocomposites with different contents of multiwalled carbon nanotubes (MWNTs) are prepared. The interaction between MWNTs and the epoxy resin matrix and the microstructure and mechanical properties of the composites are systematically investigated by Fourier-transform infrared (FTIR) spectroscopy, transmission electron microscopy, scanning electron microscopy, and positron annihilation technology. FTIR spectra reveal that two kinds of hydrogen bonds exist at the interface for the nanocomposites modified by amine, one between the epoxy group on the side chain and the NH group, and the other between the epoxy group on the alicycle and the NH group. Compared to unmodified MWNT composites, the modified MWNT composites possess better mechanical properties, which are attributed to stronger interfacial interaction resulting from an efficient load transfer from matrix to MWNTs. Positron annihilation lifetime spectroscopy is used to characterize the microstructure of the epoxy/MWNT composites. The subtransition and glass transition temperatures are determined by finite-term positron lifetime analysis and the variation of the free-volume size as a function of temperature. Shifts of structure transition temperatures of the composites are observed with increasing MWNT weight content. Interestingly, the continuous lifetime analysis reveals the existence of two long-lived lifetime components above the glass transition temperature, which may be attributed to the formation of local ordered regions related to the packing density of chains.

[Sterilizing effect and mechanism of electrolyzed water].

OBJECTIVE: To study the sterilizing effect and mechanism of electrolyzed-oxidizing water (EOW) and electrolyzed-reductive water (ERW) for Bacillus subtilis var. niger (ATCC9372) and Escherichia coli (8099). METHODS: The generations of EOW and ERW were made in the ion membrane electrolysis cell. The sterilization manner was the suspension quantitative germicidal test. RESULTS: The killing rate of EOW for Bacillus subtilis var. niger was 99.59% in 30 minutes and the killing logarithm value was 2.38 log cfu/ml; the killing rate of ERW for Bacillus subtilis var. niger was 94.62% in 60 minutes and the killing logarithm value was 1.27 log cfu/ml; the killing rate of ERW for Escherichia coli was 100% in 30 minutes and the killing logarithm value was 8.26 log cfu/ml. When the available chlorine content (ACC) value in EOW was 74.90 mg/L and killing time was 30 minutes, the killing rate for Bacillus subtilis var. niger was 99.89% and the killing logarithm value was 2.67 log cfu/ml. When the ACC value was 6.82 mg/L, the killing rate for Bacillus subtilis var. niger was 83.30% and the killing logarithm value was 0. 78 log cfu/ml under the same time. When the oxidizing-reductive potential (ORP) and pH values of EOW were 1138 mV and 2.24 respectively, the killing rate for Bacillus subtilis var. niger was 99.99%. When the ORP and pH values of EOW were 883 mV and 5. 43 respectively, the killing rate of Bacillus subtilis var. niger was 99.73%. When the ORP value of ERW is -918 mV, the sterilizing rate for Bacillus subtilis var. niger was 94.62%; when the ORP value is -155 mV, the sterilizing ratio was only 40.19%. CONCLUSION: It indicates that the sterilizing mechanism of EOW is mainly chemical processes (ACC), while the physical factors are auxiliary. The sterilizing mechanism of ERW is physics sterilizing that the mainly factor is ORP.

Study on damping mechanism based on the free volume for CIIR by PALS.

The influences of the free volume and the termperature on the damping property of chlorinated isoprene-isobutylene rubber (CIIR) were first investigated by positron annihilation lifetime spectroscopy (PALS), dynamic mechanical analysis (DMA), and differential scanning calorimetry (DSC), respectively. From the variations of ortho-positronium (o-Ps) lifetimes as a function of temperature, two transition temperatures can be observed, i.e., Tg and TB. We found that there exists a pre-rubbery state between the glass transition temperature Tg and TB. The DMA results indicate that the tan delta peak of CIIR has a very broad temperature distribution because of the existence of a liquid-liquid transition (Tll). The temperature dependence of the average free volume size can be linearly fitted below Tg and above TB, respectively. It is very interesting that the difference spectrum of the free volume size between the results fitted by two lines (below Tg and above TB) and experimental data is very similar to the dynamic mechanical spectrum of CIIR. In order to clarify the damping mechanics, the Williams-Landel-Ferry (WLF) equation based on free volume theory has been successfully used to establish a direct quantificational relationship between the free volume and the damping property, which indicates that the free volume plays an important role in determining the damping property.