Preparation of hydrogen, fluorine and chlorine doped and co-doped titanium dioxide photocatalysts: a theoretical and experimental approach

Titanium dioxide (TiO2) has a strong photocatalytic activity in the ultra-violet part of the spectrum combined with excellent chemical stability and abundance. However, its photocatalytic efficiency is prohibited by limited absorption within the visible range derived from its wide band gap value and the presence of charge trapping states located at the band edges, which act as electron-hole recombination centers. Herein, we modify the band gap and improve the optical properties of TiO2via co-doping with hydrogen and halogen. The present density functional theory (DFT) calculations indicate that hydrogen is incorporated in interstitial sites while fluorine and chlorine can be inserted both as interstitial and oxygen substitutional defects. To investigate the synergy of dopants in TiO2 experimental characterization techniques such as Fourier transform infrared (FTIR), X-ray diffraction (XRD), X-ray and ultra-violet photoelectron spectroscopy (XPS/UPS), UV-Vis absorption and scanning electron microscopy (SEM) measurements, have been conducted. The observations suggest that the oxide’s band gap is reduced upon halogen doping, particularly for chlorine, making this material promising for energy harvesting devices. The studies on hydrogen production ability of these materials support the enhanced hydrogen production rates for chlorine doped (Cl:TiO2) and hydrogenated (H:TiO2) oxides compared to the pristine TiO2 reference

Associations between Maternal and Offspring Hair Cortisol Concentrations and Child Behavioral Symptoms in Mother-Child Pairs with Perinatal Mental Disorders

Maternal perinatal mental disorders (PMD) are associated with developmental and behavioral problems in children, probably mediated by the programming of the hypothalamic–pituitary–adrenal (HPA) axis. Increased cortisol concentrations during the antenatal and perinatal periods have been related to long-term effects on children’s behavior and stress response. We aimed to investigate the association of hair cortisol concentrations (HCC) between mothers, with (n = 16) and without PMD (n = 30), and their children, aged between 18 and 48 months. Participants were evaluated with a clinical interview and questionnaires for the Depression Anxiety Stress Scale and the Child Behavior Checklist for ages 1½–5. Maternal and child HCCs were compared between the two groups. Children of the PMD group had increased symptoms of attention deficit hyperactivity disorder. A positive linear association between maternal and child HCC was observed only in the total sample of mother–child dyads and the control group. In the PMD group, children’s HCCs were significantly associated with child anxiety/depression symptoms. Aggressive behavior and oppositional/defiant problems correlated significantly with children’s own HCCs, and their mother’s too. These findings suggest that a chronic dysregulation of maternal and child HPA axis and their associations in the PMD dyads may underlie the linkage among prolonged maternal stress, child behavioral/emotional problems and stress responses

Dye‐Sensitized Photocatalysis: Hydrogen Evolution and Alcohol‐to‐Aldehyde Oxidation without Sacrifical Electron Donor

There is a growing interest in developing dye‐sensitized photocatalytic systems (DSPs) to produce molecular hydrogen (H 2 ) as alternative energy source. To improve the sustainability of this technology, we replaced the sacrificial electron donor (SED), typically an expensive and polluting chemical, with an alcohol oxidation catalyst. This study demonstrates the first dye‐sensitized system using a diketopyrrolopyrrole dye covalently linked to 2,2,6,6‐tetramethyl‐1‐piperidine‐ N ‐oxyl (TEMPO) based catalyst for simultaneous H 2 evolution and alcohol‐to‐aldehyde transformation operating in water with visible irradiation.</p