Photoactivity of amorphous and crystalline TiO2 nanotube arrays (TNA) films in gas phase CO2 reduction to methane with simultaneous H2 production.

This study assessed the photoactivity of amorphous and crystalline TiO2 nanotube arrays (TNA) films in gas phase CO2 reduction. The TNA photocatalysts were fabricated by titanium anodization and submitted to an annealing treatment for crystallization and/or cathodic reduction to introduce Ti3+ and oxygen vacancies into the TiO2 structure. The cathodic reduction demonstrated a significant effect on the generated photocurrent. The photoactivity of the four TNA catalysts in CO2 reduction with water vapor was evaluated under UV irradiation for 3 h, where CH4 and H2 were detected as products. The annealed sample exhibited the best performance towards methane with a production rate of 78 µmol gcat-1 h-1, followed by the amorphous film, which also exhibited an impressive formation rate of 64 µmol gcat-1 h-1. The amorphous and reduced-amorphous films exhibited outstanding photoactivity regarding H2 production (142 and 144 µmol gcat-1 h-1, respectively). The annealed catalyst also revealed a good performance for H2 production (132 µmol gcat-1 h-1) and high stability up to five reaction cycles. Molecular dynamic simulations demonstrated the changes in the band structure by introducing oxygen vacancies. The topics covered in this study contribute to the Sustainable Development Goals (SDG), involving affordable and clean energy (SDG#7) and industry, innovation, and infrastructure (SDG#9).

Evaluation of the hydrogenation reaction on the electrocatalytic nitrobenzene degradation over (FeCoNiCuZn)xOy high entropy oxides (HEOs).

Environmental pollution is one of the main challenges currently faced by mankind; especially industrial waste-waters treatment and remediation using energy-efficient methodologies. This research focused on the electrochemical degradation of the hazardous nitrobenzene (NB) in aqueous solutions, using novel high-entropy oxide (HEO) electrodes to elucidate the influence of the electrochemical reduction step on the degradation process. The effect of solution pH, dissolved oxygen concentration, anodic applied potential, and cell configurations on NB hydrogenation reaction were evaluated. A synergistic effect between the hydrogenation of nitrobenzene and the degradation was found to drastically enhance the conversion rates. The presence of dissolved oxygen promoted the oxidation reactions, reaching more than 90% nitrobenzene removal at 1.7 V and pH 14. The degradation of the organic by-products was attributed to the formation of the superoxide radical (O2*-) as the main oxidant species. A degradation mechanism was proposed based on the detected intermediates and the decoupling of electrochemical surface reactions observed by EIS at different solution pH.

Single-step fabrication of highly stable amorphous TiO2 nanotubes arrays (am-TNTA) for stimulating gas-phase photoreduction of CO2 to methane.

This study investigates the facile fabrication of interfacial defects assisted amorphous TiO2 nanotubes arrays (am-TNTA) for promoting gas-phase CO2 photoreduction to methane. The am-TNTA catalyst was fabricated via a one-step synthesis, without heat treatment, by anodization of Titanium in Ethylene glycol-based electrolyte in a shorter anodizing time. The samples presented a TiO2 nanostructured array with a nanotubular diameter of 100 ± 10 nm, a wall thickness of 26 ± 5 nm, and length of 3.7 ± 0.3 µm, resulting in a specific surface of 0.75 m2 g. The am-TNTA presented prolonged chemical stability, a high exposed surface area, and a large number of surface traps that can reduce the recombination of the charge carriers. The am-TNTA showed promising photoactivity when tested in the CO2 reduction reaction with water under UV irradiation with a methane production rate of 14.0 µmol gcat-1 h-1 for a pure TiO2 material without any modification procedure. This enhanced photocatalytic activity can be explained in terms of surface defects of the amorphous structure, mainly OH groups that can act as electron traps for increasing the electron lifetime. The CO2 interacts directly with those traps, forming carbonate species, which favors the catalytic conversion to methane. The am-TNTA also exhibited a high stability during six reaction cycles. The photocatalytic activity, the significantly reduced time for synthesis, and high stability for continuous CH4 production make this nanomaterial a potential candidate for a sustainable CO2 reduction process and can be employed for other energy applications.

Day/night melatonin content in cerebral palsy.

Changes in the sleep-wake cycle are frequent and may impair quality of life in individuals with cerebral palsy (CP). To investigate if a lack of a day/night variation of melatonin content could be related with sleep disorders (SD), the SD were evaluated with a Sleep Questionnaire and the melatonin content using ELISA in 33 individuals with CP and 24 controls. The indicative of SD were present in 47% of CP group, and the most frequent was the indicative of sleep breathing disorder. The CP group showed higher diurnal and lower nocturnal melatonin content than controls. Individuals with CP that had indicative of SD showed lower nocturnal content of melatonin than those without SD. These results showed that the lack of the day/night variation of melatonin was related to SD in individuals with CP.