Scaling Up Electrodes for Photoelectrochemical Water Splitting: Fabrication Process and Performance of 40†cm2 LaTiO2 N Photoanodes.

A scalable process for fabrication of particle-based photoanodes is developed. The electrodes are versatilely made of photocatalytically active semiconductor particles, in this case LaTiO2 N, and optionally coated with cocatalysts and protecting components, all immobilized on a conducting substrate. The involved fabrication steps are restricted to scalable processes such as electrophoretic deposition, annealing in air, and dip coating. Special care is taken to ensure efficient charge transport in-between particles and to the substrate by incorporating conducting connectors. By adapting the fabrication steps, the electrode geometrical dimension is increased from the size of a typical lab electrode of 1 to 40 cm2 . The quality of the scale-up process is characterized by comparing the photoanodes in terms of thickness, light-absorption properties, and morphology. For several compositions, the electrochemical performance of both electrode sizes is assessed by measuring the photocurrents and faradaic efficiencies. The comparison revealed a complex upscaling behavior and showed that the photoelectrode size affects performance already on the 0.1 m scale.

Controlled Design of Functional Nano-Coatings: Reduction of Loss Mechanisms in Photoelectrochemical Water Splitting.

Efficient water splitting with photoelectrodes requires highly performing and stable photoactive materials. Since there is no material known which fulfills all these requirements because of various loss mechanisms, we present a strategy for efficiency enhancement of photoanodes via deposition of functional coatings in the nanometer range. Origins of performance losses in particle-based oxynitride photoanodes were identified and specifically designed coatings were deposited to address each loss mechanism individually. Amorphous TiO2 located at interparticle boundaries enables high electron conductivity. A thin layer of amorphous Ta2O5 can be used as protection layer for photoanodes because of its hole conductivity and thermal and chemical stability. An amorphous layer of NiOx and Co(OH)2 reduces photocorrosion or increases water oxidation kinetics because they act as a hole-capture material or water oxidation catalyst, respectively. Crystalline CoOx nanoparticles increase photocurrent and reduce the onset potential due to enhanced charge separation. The combination of all coatings deposited by a scalable, mild, and reproducible step-by-step approach leads to high-performance oxynitride-based photoanodes providing a maximum photocurrent of 2.52 mA/cm(2) at 1.23 VRHE under AM1.5G illumination.

Size-selected gold clusters on porous titania as the most "gold-efficient" heterogeneous catalysts.

Research on homogeneous and heterogeneous catalysis is indeed convergent and finds subnanometric particles to be at the heart of catalytically active species. Here, monodisperse gold clusters are deposited from the gas phase onto porous titania generating well-defined model systems and the resulting composite materials exhibit a sharp size-dependency on the number of gold atoms per cluster and exceptionally high-turnovers toward the bromination of 1,4-dimethoxybenzene are observed. This indicates that the deliberate generation of active centres is of utmost importance for the creation of the most "gold-efficient" catalysts.

Hierarchical zinc oxide materials with multiple porosity prepared by ultrafast temperature gradient chemical gas-phase synthesis.

The preparation of materials characterized by three types of porosity could be prepared by a continuous chemical gas-phase method. The multistep formation mechanism involves a critical temperature gradient and occurs within seconds. The resulting hollow aerogel materials show superior properties as gas sensors in comparison to materials constructed from compact nanoparticles.

Short-term monitoring of cognitive functions before and during the first course of treatment.

PURPOSE: Side effects of chemotherapy on cognitive functions in older patients have rarely been investigated. Addressing this lack of research, the present study evaluated cognitive functions in older cancer patients. METHODS: A total of 130 younger (n=59; age<60) and older (n=71; age>or=60) cancer patients with hematological disease or cancer of the intestinal tract took part in the study. To explore short-term effects of chemotherapy, a group of patients assessed before the start of chemotherapy was compared with patients who already received their first course of chemotherapy. RESULTS: Cognitive impairments of verbal learning, word fluency, and memory were observed following the first few days after treatment onset. Older patients showed stronger memory impairments after start of chemotherapy than younger cancer patients. Additionally, depression was neither associated with short-term effect of chemotherapy nor with age. CONCLUSIONS: The results suggest that chemotherapy has negative short-term effects on some cognitive functions. But age-dependent effects were only found for memory.

Effects of cognitive-behavioral therapy on brain activation in specific phobia.

Little is known about the effects of successful psychotherapy on brain function in subjects with anxiety disorders. The present study aimed to identify changes in brain activation following cognitive-behavioral therapy (CBT) in subjects suffering from specific phobia. Using functional magnetic resonance imaging (fMRI), brain activation to spider videos was measured in 28 spider phobic and 14 healthy control subjects. Phobics were randomly assigned to a therapy-group (TG) and a waiting-list control group (WG). Both groups of phobics were scanned twice. Between scanning sessions, CBT was given to the TG. Before therapy, brain activation did not differ between both groups of phobics. As compared to control subjects, phobics showed greater responses to spider vs. control videos in the insula and anterior cingulate cortex (ACC). CBT strongly reduced phobic symptoms in the TG while the WG remained behaviorally unchanged. In the second scanning session, a significant reduction of hyperactivity in the insula and ACC was found in the TG compared to the WG. These results propose that increased activation in the insula and ACC is associated with specific phobia, whereas an attenuation of these brain responses correlates with successful therapeutic intervention.

Medium-term effects of chemotherapy in older cancer patients.

PURPOSE: To address the lack of research in older cancer patients, the present study prospectively evaluated their cognitive functions across the first six months following diagnosis and chemotherapy. PATIENTS AND METHODS: A total of 77 younger (n=43, age < 60) and older (n=34, age > or = 60) cancer patients with hematological disease or cancer of the intestinal tract took part in the study. Medium-term effects of chemotherapy were examined in these cancer patients by means of a battery of cognitive tests during baseline and six months after start of treatment. RESULTS: In contrast to baseline verbal learning, word fluency and memory capacity improved in all patients six months after start of treatment. A negative effect of age on cognitive functions could not be demonstrated. Additionally, depression was neither associated with medium-term effects of chemotherapy nor was it related to age. CONCLUSION: The results suggest that chemotherapy has no negative effects on cognitive functions after the first six months following the onset of treatment. It was demonstrated that complete recovery of cognitive functions is independent of the patient's age.

Brain activation to phobia-related pictures in spider phobic humans: an event-related functional magnetic resonance imaging study.

Using event-related functional magnetic resonance imaging we investigated blood oxygen level dependent brain activation in spider phobic and non-phobic subjects while exposed to phobia-related pictures (spiders) and non-phobia-related pictures (snakes and mushrooms). In contrast to previous studies, we show significantly increased amygdala activation in spider phobics, but not in controls, during presentation of phobia-relevant visual stimuli. Furthermore, phobia-specific increased activation was also found in the insula, the orbitofrontal cortex and the uncus. Our study confirms the role of the amygdala in fear processing and provides insights into brain activation patterns when animal phobics are confronted with phobia-related stimuli.