Preparation of electrolyzed oxidizing water by TiO2 doped IrO2-Ta2O5 electrode with high selectivity and stability for chlorine evolution

Enhancing Ru-Cl interaction via orbital hybridization effect in Ru0.4Sn0.3Ti0.3 electrode for efficient chlorine evolution

Chlorine evolution reaction (CER) is a commercially valuable electrochemical reaction used at an industrial scale. However, oxygen evolution reaction (OER) during the electrolysis process inevitably leads to the decreased efficiency of CER. It is necessary to improve the selectivity of CER by minimizing or even eliminating the occurrence of OER. Herein, a ternary metal oxide (Ru0.4Sn0.3Ti0.3) electrode was fabricated and employed as an active and robust anode for CER. The Ru0.4Sn0.3Ti0.3 electrode exhibits an excellent CER performance in 6.0 M NaCl solution, with a low potential of 1.17 V (vs. saturated calomel electrode, SCE) at 200 mA cm-2 current density, a high Cl2 selectivity of over 90 %, and robust durability after consecutive operation for 160 h under 100 mA cm-2. The maximum O2-Cl2 potential difference between OER and CER further demonstrates the high Cl2 selectivity of Ru0.4Sn0.3Ti0.3 electrode. Theoretical studies show that the strong Ru 3d-Ti 3d orbitals hybridization effect makes the d-band center (εd) of Ru 3d and Ti 3d orbitals positively and negatively shifted, respectively, endowing Ru site with enhanced Cl adsorption ability (i.e. enhanced Ru-Cl interaction) and Ru0.4Sn0.3Ti0.3 electrode with superior CER activity. This work offers valuable insights into the development of advanced electrodes for CER in practical application.

C60- and CdS-Co-Modified Nano-Titanium Dioxide for Highly Efficient Photocatalysis and Hydrogen Production

The inherent properties of TiO2, including a wide band gap and restricted spectral response range, hinder its commercial application and its ability to harness only 2-3% of solar energy. To address these challenges and unlock TiO2's full potential in photocatalysis, C60- and CdS-co-modified nano-titanium dioxide has been adopted in this work to reduce the band gap, extend the absorption wavelength, and control photogenerated carrier recombination, thereby enhancing TiO2's light-energy-harnessing capabilities and hydrogen evolution capacity. Using the sol-gel method, we successfully synthesized CdS-C60/TiO2 composite nanomaterials, harnessing the unique strengths of CdS and C60. The results showed a remarkable average yield of 34.025 μmol/h for TiO2 co-modified with CdS and C60, representing a substantial 17-fold increase compared to pure CdS. Simultaneously, the average hydrogen generation of C60-modified CdS surged to 5.648 μmol/h, a notable two-fold improvement over pure CdS. This work opens up a new avenue for the substantial improvement of both the photocatalytic degradation efficiency and hydrogen evolution capacity, offering promise of a brighter future in photocatalysis research.

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 OH_ads. 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.

Degradation of Dibutyl Phthalate Plasticizer in Water by High-Performance Iro2-Ta2O5/Ti Electrocatalytic Electrode

Dibutyl phthalate (DBP) in the presence of a wastewater system is harmful to the environment and interferes with the human’s endocrine system. For wastewater treatment, DBP is very difficult to be decomposed by biotechniques and many catalytic processes have been developed. Among them, the electrocatalytic oxidation (EO) technique has been proven to possess high degradation efficiency of various organic compounds in wastewater. In this study, an electrocatalytic electrode of iridium-tantalum/titanium (IrO2-Ta2O5/Ti) was employed as the anode and graphite as the cathode to decompose DBP substances in the water. According to experimental results, the high removal efficiency of DBP and total organic carbon (TOC) of 90% and 56%, respectively, could be obtained under a voltage gradient of 10 V/cm for 60 min. Compared with other photocatalysis degradation, the IrO2-Ta2O5/Ti electrode could shorten about half the treatment time and electric power based on the same removal efficiency of DBP (i.e., photocatalysis requires 0.225~0.99 KWh). Results also indicated that the production of hydroxyl radical (•OH) in the electrocatalytic electrode played a key role for decomposing the DBP. Moreover, the pH and conductivity of water containing DBP were slightly changed and eventually remained in a stable state during the EO treatment. In addition, the removal efficiency of DBP could still remain about 90% after using the IrO2-Ta2O5/Ti electrode three times and the surface structure of the IrO2-Ta2O5/Ti electrode was stable.

Recent Progress in Catalysts for Hydrogen-Chlorine Regenerative Fuel Cells

The increasing energy demand and the subsequent climate change consequences are supporting the search for sustainable alternatives to fossil fuels. In this scenario, the link between hydrogen and renewable energy is playing a key role and unitized hydrogen-chlorine (H2-Cl2) regenerative cells (RFCs) have become promising candidates for renewable energy storage. Described herein are the recent advances in cell configurations and catalysts for the different reactions that may take place in these systems, that work in both modes: electrolysis and fuel cell. It has been found that platinum (Pt)-based catalysts are the best choice for the electrode where hydrogen is involved, whereas for the case of chlorine, ruthenium (Ru)-based catalysts are the best candidates. Only a few studies were found where the catalysts had been tested in both modes and recent advances are focused on decreasing the amount of precious metals contained in the catalysts. Moreover, the durability of the catalysts tested under realistic conditions has not been thoroughly assessed, becoming a key and mandatory step to evaluate the commercial viability of the H2-Cl2 RFC technology.

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.