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Real-time sensing of chemical warfare agents (CWAs) is, today, a crucial topic to prevent lethal effects of a chemical terroristic attack. For this reason, the development of efficient, selective, sensitive, and reversible sensoristic devices, which are able to detect by optical response the ppm levels of these compounds, both in water and in air, is strongly required. Here, we report the design and synthesis of a fluorescent nanosensor, based on carbon nanoparticles covalently functionalized with ethanolamine arms, which exploits the multitopic supramolecular interaction with nerve agents, ensuring highly efficient (log K 6.46) and selective molecular recognition. Moreover, given the aqueous dispersibility of carbon nanoparticles, these nanosensors ensure even higher sensitivity, detecting sub-ppt concentration of nerve agents in water, and subppm level in air by using a common digital camera or a smartphone. Our results pave the way to an innovative class of low-cost reusable CWA sensors, prompting, for the first time, the simultaneous detection of nerve agents through gaseous and aqueous media, thus extending the protection range to public water supplies.

The thermocatalytic, photocatalytic and photothermo-catalytic oxidation of some volatile organic compounds (VOCs), 2-propanol, ethanol and toluene, was investigated over brookite TiO2-CeO2 composites. The multi-catalytic approach based on the synergistic effect between solar photocatalysis and thermocatalysis led to the considerable decrease in the conversion temperatures of the organic compounds. In particular, in the photothermo-catalytic runs, for the most active samples (TiO2-3 wt% CeO2 and TiO2-5 wt% CeO2), the temperature at which 90% of VOC conversion occurred was about 60 °C, 40 °C and 20 °C lower than in the thermocatalytic tests for 2-propanol, ethanol and toluene, respectively. Furthermore, the addition of cerium oxide to brookite TiO2 favored the total oxidation to CO2 already in the photocatalytic tests at room temperature. The presence of small amounts of cerium oxide allowed to obtain efficient brookite-based composites facilitating the space charge separation and increasing the lifetime of the photogenerated holes and electrons as confirmed by the characterization measurements. The possibility to concurrently utilize the photocatalytic properties of brookite and the redox properties of CeO2, both activated in the photothermal tests, is an attractive approach easily applicable to purify air from VOCs.

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Abstract:The catalytic performances of Ru/ceria-based catalysts in the CO preferential oxidation (CO-PROX) reaction are discussed here. Specifically, the effect of the addition of different oxides to Ru/CeO 2 has been assessed. The Ru/CeO 2 -MnO x system showed the best performance in the 80-120 • C temperature range, advantageous for polymer-electrolyte membrane fuel cell (PEMFC) applications. Furthermore, the influence of the addition of different metals to this mixed oxide system has been evaluated. The bimetallic Ru-Pd/CeO 2 -MnO x catalyst exhibited the highest yield to CO 2 (75%) at 120 • C whereas the monometallic Ru/CeO 2 -MnO x sample was that one with the highest CO 2 yield (60%) at 100 • C. The characterization data (H 2 -temperature programmed reduction (H 2 -TPR), X-ray diffraction (XRD), N 2 adsorption-desorption, diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), X-ray photoelectron spectroscopy (XPS)) pointed out that the co-presence of manganese oxide and ruthenium enhances the mobility/reactivity of surface ceria oxygens accounting for the good CO-PROX performance of this system. Reducible oxides as CeO 2 and MnO x , in fact, play two important functions, namely weakening the CO adsorption on the metal active sites and providing additional sites for adsorption/activation of O 2 , thus changing the mechanism from competitive Langmuir-Hinshelwood into non-competitive one-step dual site Langmuir-Hinshelwood/Mars-van Krevelen. As confirmed by H 2 -TPR and XPS measurements, these features are boosted by the simultaneous presence of ruthenium and palladium. The strong reciprocal interaction of these metals between them and with the CeO 2 -MnO x support was assumed to be responsible of the promoted reducibility/reactivity of CeO 2 oxygens, thus resulting in the best CO-PROX efficiency at low temperature of the Ru-Pd/CeO 2 -MnO x catalyst. The higher selectivity to CO 2 found on the Ru-Pd system, which reduces the undesired H 2 consumption, represents a promising result of this research, being one of the key aims of the design of CO-PROX catalysts.

Broadband transparent conductive oxide layers with high electron mobility (μe) are essential to further enhance crystalline silicon (c-Si) solar cell performances. Although metallic cation-doped In2O3 thin films with high μe (>60 cm2 V–1 s–1) have been extensively investigated, the research regarding anion doping is still under development. In particular, fluorine-doped indium oxide (IFO) shows promising optoelectrical properties; however, they have not been tested on c-Si solar cells with passivating contacts. Here, we investigate the properties of hydrogenated IFO (IFO:H) films processed at low substrate temperature and power density by varying the water vapor pressure during deposition. The optimized IFO:H shows a remarkably high μe of 87 cm2 V–1 s–1, a carrier density of 1.2 × 1020 cm–3, and resistivity of 6.2 × 10–4 Ω cm. Then, we analyzed the compositional, structural, and optoelectrical properties of the optimal IFO:H film. The high quality of the layer was confirmed by the low Urbach energy of 197 meV, compared to 444 meV obtained on the reference indium tin oxide. We implemented IFO:H into different front/back-contacted solar cells with passivating contacts processed at high and low temperatures, obtaining a significant short-circuit current gain of 1.53 mA cm–2. The best solar cell shows a conversion efficiency of 21.1%.

Gold nanoparticles show important properties owing to their electronic structures. A limitation of some gold nanoparticles is that they either show surface plasmons or luminescence. The increase in size of the gold nanoparticles, and the appearance of the surface plasmons may result in the disappearance of luminescence. The aim of our study is the nanoscale assembly of Au nanoparticles on a monolayer of porphyrin molecules anchored to functionalized inorganic surfaces. This functional architecture not only exhibits a strong surface plasmon due to the gold nanoparticles, but also a strong luminescence signal from the porphyrin molecules. Finally we observed a long-range order in the Au nanoparticles conjugated to the porphyrin monolayer.

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