Quantitative Determination the Role of the Intrabandgap States in Water Photooxidation over Hematite Electrodes.

The intrabandgap states on the hematite (α-Fe2O3) electrodes are believed to play an important role in water photooxidation. Yet, it is not fully understood how the intrabandgap states are involved in the reaction. In this work, the intraband-gap states in water photooxidation on α-Fe2O3 electrodes are investigated by a combination of multiple (photo-) electrochemical techniques and operando spectroscopic methods. Two kinds of surface states are observed on the electrodes during water photooxidation, and their roles are quantitatively determined by the correlation with the steady-state photocurrent. It is demonstrated that the intrinsic electronic surface state close to the conduction band can act only as the recombination center for the photocarriers. However, the photogenerated surface state closer to the valence band is revealed to be the reactant in the rate-determining step in oxygen evolution reaction. These findings may be beneficial to elucidate the actual function of the surface states and provide insights into the kinetic and mechanism studies of water photooxidation on the α-Fe2O3 electrodes.

Unconventional rate law of water photooxidation at TiO2 electrodes.

Photoelectrochemical oxidation of water over semiconductors is a promising route for the production of sustainable solar fuels. TiO2 water photooxidation has been intensively studied over the past 50 years, but its rate law and mechanism are still undetermined. The main challenges are that there is no appropriate reaction kinetic model currently, and that both the reaction rate constant and reactant photohole concentration/density are not readily quantified with respect to conventional chemical reactions. Here we report that the rate law and photohole transfer mechanism could be determined by a combination of multiple (photo-) electrochemical techniques. We demonstrate that the kinetics of TiO2 water oxidation by photogenerated holes can be well-described by a model of surface state mediating charge transfer and recombination. The rate law, in terms of steady-state photocurrent, is the product of the surface hole density exponential dependent rate constant and the surface hole density, with first order for all the surface hole densities studied. This reactant concentration dependent rate constant is conceptually unexpected for an elementary step in conventional chemical reactions. In addition, we find that hydroxyl ions in bulk solutions are involved in the reaction as indicated by observation of the solution pH dependent apparent rate constant. This study may thus lead to key insights both for strategies to evaluate and/or enhance photoelectrochemical performances and for understanding reaction mechanisms.

Base-metal oxide semiconductor electrodes for PPCP degradation: Ti-doped α-Fe2O3 for sulfosalicylic acid oxidation as an example.

Sulfosalicylic acid is a typical pharmaceutical and personal care product with high toxicity, environmental persistence, and low biodegradability. Electrochemical oxidation has been demonstrated to be a promising way for hazardous organics treatment, but it is severely limited by the high cost and resource shortage of electrode materials. Base-metal oxide semiconductor anodes have the merits of low cost, diversity, and tunable energy levels for charge transfer, and thus may be alternatives to the electrodes for wastewater treatment. Herein, we found that Ti-doped α-Fe2O3, as an example, could be efficient for sulfosalicylic acid oxidation, reaching comparable faraday efficiency of sulfosalicylic acid to that of the boron-doped diamond electrode. Ti-doped electrodes exhibited both higher removal rates and current efficiency compared to the undoped. This could be mainly ascribed to the enhanced charge transfer rate constant. Kinetic analysis shows that the apparent reaction order, in terms of sulfosalicylic acid in bulk solution, depended on applied potential and pollutant concentration. Mechanism study shows that the oxidation of sulfosalicylic acid was mainly through indirect pathway. Moreover, the oxidation products were determined and the oxidation mechanism was proposed. This study may open a door to employ base-metal oxide semiconductor anodes for the efficient treatment of organic wastewater.

Use of GLP1RAs and occurrence of respiratory disorders: A meta-analysis of large randomized trials of GLP1RAs.

OBJECTIVES: No large sample studies have been designed to evaluate the efficacy of glucagon-like peptide-1 receptor agonists (GLP1RAs) in the primary and secondary prevention of respiratory disorders. We aimed at evaluating the relationship between use of GLP1RAs and occurrence of 12 kinds of respiratory disorders. METHODS: Large randomized placebo-controlled trials of GLP1RAs were included. We conducted meta-analysis using random effects model and measured heterogeneity using I2 . Treatment effect was presented as risk ratio (RR) and 95% confidence interval (CI). RESULTS: Seven trials including 55 922 participants were included in meta-analysis. The occurrence rates of various respiratory disorders were low, with the minimum of 0.02% (pulmonary fibrosis) and the maximum of 2.31% (pneumonia). Although not reaching statistical significance, GLP1RAs versus placebo showed the reduced trends in the risks of nine kinds of respiratory disorders including pneumonia (RR 0.89, 95% CI 0.78-1.01), squamous cell carcinoma of lung (SCCL; RR 0.55, 95% CI 0.25-1.21), asthma (RR 0.82, 95% CI 0.51-1.32), and chronic obstructive pulmonary disease (COPD; RR 0.89, 95% CI 0.73-1.10), but the increased trend in interstitial lung disease (ILD; RR 1.89, 95% CI 0.87-4.08). GLP1RAs had neutral effects on two other respiratory disorders. Heterogeneity in any meta-analysis was absent or low. CONCLUSION: GLP1RAs show the reduced trends in the risks of nine kinds of respiratory disorders (eg, pneumonia, SCCL, asthma, and COPD), but the increased trend in the risk of ILD. However, these findings need to be validated by further studies due to the low incidence rates of all the respiratory disorders.

Efficacy and safety of S-1 maintenance therapy in advanced non-small-cell lung cancer patients.

BACKGROUND: Previous reports have demonstrated that S-1 has remarkable effects in the maintenance treatment of advanced non-small-cell lung cancer (NSCLC), and has less toxic and side effects than conventional drugs. AIM: To investigate the efficacy and safety of S-1 maintenance therapy in patients with advanced NSCLC. METHODS: Ninety-four patients with NSCLC admitted to our hospital from September 2015 to April 2018 were included in the study and divided into the S-1 group (47 cases) and the gemcitabine group (47 cases) by random digital table method. The S-1 group was treated with S-1, while the gemcitabine group received gemcitabine treatment. The clinical efficacy and quality of life of the patients after treatment in the two groups were evaluated. RESULTS: There was no significant difference in the total effectiveness rate between the two groups (P = 0.519). The quality-of-life scores indicated that there was no significant difference between the two groups in terms of four dimensions of the GQOLI-74 questionnaire (P = 0.518, 0.094, 0.338, 0.418). The incidence of nausea and vomiting, granulocytopenia and diarrhea in the S-1  group was significantly lower than that in the gemcitabine group (P = 0.001, 0.001 and 0.001, respectively). There was no significant difference in the incidence of thrombocytopenia (P = 0.366), the progression-free survival (P = 0.064), and the survival between the two groups (P = 0.050). CONCLUSION: S-1 maintenance therapy shows a significant therapeutic effect in patients with advanced NSCLC. It has the same clinical efficacy as gemcitabine, but with less toxic and side effects than conventional drugs.

Understanding the enhanced photoelectrochemical water oxidation over Ti-doped α-Fe2O3 electrodes by electrochemical reduction pretreatment.

Water splitting using semiconductor photoelectrodes is a promising approach to solar hydrogen production. Previous studies have well-demonstrated that electrochemical reduction (ER) pretreatment of bare and Ti-doped α-Fe2O3 electrodes enhances water photooxidation efficiencies, however, the mechanism underlying this improvement remains poorly understood. In this study, this was quantitatively investigated by multiple photoelectrochemical techniques and transient absorption spectroscopy, using the doped electrodes as examples. The results reveal that the kinetics of photoholes after moving to the electrode surface can be well described by a model of surface-state mediated charge transfer and recombination. The reason for the photocurrent enhancement is attributed to a significantly increased charge transfer rate constant (kct) and a decreased surface recombination rate constant (ksr) by ER. The reason for the accelerated kct is that a new type of surface state, with a favorable energy position for water oxidation, is produced. The decreased ksr is due to the reduced electron density at the surface of the semiconductor, resulted predominately from the negatively shifted flat band potential. These findings provide new insights into the mechanism of water photooxidation and enlighten a simple way to develop more efficient electrodes.

Catalytic Upgrading of Ethanol to n-Butanol: Progress in Catalyst Development.

Because n-butanol as a fuel additive has more advantageous physicochemical properties than those of ethanol, ethanol valorization to n-butanol through homo- or heterogeneous catalysis has received much attention in recent decades in both scientific and industrial fields. Recent progress in catalyst development for upgrading ethanol to n-butanol, which involves homogeneous catalysts, such as iridium and ruthenium complexes, and heterogeneous catalysts, including metal oxides, hydroxyapatite (HAP), and, in particular, supported metal catalysts, is reviewed herein. The structure-activity relationships of catalysts and underlying reaction mechanisms are critically examined, and future research directions on the design and improvement of catalysts are also proposed.

Charge carrier separation in nanostructured TiO2 photoelectrodes for water splitting.

There is intense interest in developing new novel nanostructured photoanodes for water splitting. It is therefore important that methods to analyze the effect of nanostructuring on water splitting yields are developed in order to rationalize the relative merits of this approach for different materials. In this study the dependence of charge separation efficiency (η(sep)) on potential during photoelectrochemical water splitting at pH 2 has been quantified in a model electrode system (nanocrystalline, mesoporous TiO2) using two independent methods. These are (i) analysis of incident photon conversion efficiency (IPCE) measurements and (ii) transient absorption (TA) spectroscopy measurements. The techniques provide good agreement with each other and show that a low maximum value of η(sep) (~0.18) is the primary cause of the low IPCE for water oxidation on these nc-TiO2 electrodes.

Effect of surface Fe2O3 clusters on the photocatalytic activity of TiO2 for phenol degradation in water.

Surface modification of TiO(2) with Fe(2)O(3) clusters was made through chemisorption of ferric phthalocyaninetetracarboxylate onto TiO(2), followed by sintering in air to remove organic moiety. Solid characterization with electron paramagnetic resonance spectroscopy and other techniques showed that ferric oxides were highly dispersed on TiO(2) as a noncrystallized cluster, while TiO(2) phases remained unchanged. For phenol degradation in aerated aqueous suspension, only the sample containing less than 0.3 at.% Fe was more active than bare TiO(2) under UV light, whereas no activity was found under visible light. As anatase thermally transferred into rutile, the Fe-containing catalyst became less active than bare TiO(2), mainly ascribed to the increased size of Fe(2)O(3) clusters. In the presence of H(2)O(2), all Fe-containing catalysts were more active than bare TiO(2). Moreover, similar trend in activity among different catalysts was also observed with the formation of hydroxyl radicals, and with the generation of photocurrent measured under N(2) with Fe/TiO(2) electrode. Present work clearly shows that only Fe(2)O(3) clusters in a small size and at low coverage on TiO(2) are beneficial to the photocatalytic reaction, while excess iron oxide is detrimental. Possible mechanism is discussed in the text.

Photocatalytic oxidation of arsenite over TiO2: is superoxide the main oxidant in normal air-saturated aqueous solutions?

TiO(2) photocatalytic oxidation (PCO) of As(III) in the normal air-saturated aqueous solutions has been widely studied. Yet no consensus has been achieved on the mechanism whether superoxide is the main oxidant, although many approaches have been taken. (Photo)electrochemical method can minimize changes to TiO(2) surface and could therefore not alter the normal mechanism. In this Article, both this approach and As(III) oxidation kinetic measurements were performed to clarify the disputed mechanism. Under a sufficient cathodic bias potential, the dark oxidation of As(III) by superoxide could occur, but both the reaction rate and the columbic efficiency were rather low, suggesting that it is a weak oxidant. However, under UV light, both the reaction rate and the columbic efficiency were greatly enhanced even at potentials negative enough to eliminate photohole participation, indicating that more efficient oxidants than superoxide were produced. Under UV illumination and enough positive potential where superoxide was absent, the As(III) oxidation was the most highly efficient. The columbic efficiency of photoholes was much higher than that of superoxide. In the normal aerated aqueous solutions and at open circuit, although the total contribution of superoxide and its derivates to the PCO of As(III) was considerably high (up to 43%), it was not more than that of photohole (57%). In addition, the reported various approaches taken to elucidate the mechanism were discussed, and the resulting disputes can be clarified by these findings. It was demonstrated that (photo)electrochemical method could provide direct and undisputed evidence to reveal the truth mechanics issues.

[C2H4 reducing facility for controlled ecological life support system].

OBJECTIVE: To develop an experimental facility for reducing C2H4 produced by plants' growing in the controlled ecological life support system (CELSS). METHOD: Based on technical parameters and performance requirements, project planning, design drawing, fabrication, and debug were conducted. Then, an experimental test for reducing C2H4 was done by measuring the content of C2H4 in gases between the inlet and the outlet of the facility. Its C2H4 decomposing capacity was evaluated. RESULT: The facility worked well, and the parameters, such as energy consumption, and volume, met the design requirements. The experimental test results demonstrated that the content of C2H4 was reduced from 0.034 mg/kg to below 0.010 mg/kg, under the condition that the relative humidity and velocity of flow of the inlet-gas was 20% and 1.0-3.0 L/min respectively, and power of the lamp was 48 W. Considering the composition and the content of the gas in the outlet of the facility, there was no harmful product to the plants, except CO2 and H2O. CONCLUSION: The facility has reasonable technical indices, and smooth and dependable performances. It can be used as a facility for decomposing C2H4 in plants growing system in CELSS.

Characteristics of MnO2 catalytic ozonation of sulfosalicylic acid and propionic acid in water.

The characteristics of different types of MnO(2) catalytic ozonation of sulfosalicylic acid (SSal) and propionic acid (PPA) have been investigated in this paper. The experimental results show the dependence of catalytic activity of MnO(2) on organic compounds and the pH of solutions, but it is independent on the type of MnO(2). For example, three types of MnO(2) have not any catalytic activity when ozonation of PPA under the condition of this experiment. All MnO(2) catalytic ozonation of SSal at pH=1.0 have a greater total organic carbon removal than ozonation alone has, however, at pH=6.8 and 8.5, catalytic efficiency is not observed. Furthermore, the batch experimental results indicate that there are no direct relationship between the activity of metal oxide catalytic decomposition of ozone and that of its catalytic degradation of organic compounds.