Geographic origin differentiation of Philippine civet coffee using an Electronic nose

An increasing interest in geographical indication of origin has emerged to achieve legal protection of specialty coffee in international market. Civet coffee which is considered as the most expensive and best specialty coffee in the world, is one of the important indigenous export products of the Philippines. Thus, geographical origin differentiation of Philippine civet coffee and their control coffee beans (not eaten by civet) using electronic nose (E-nose) was performed. The E-nose instrument was based on six semiconductor metal oxide (SMO) sensor array. Results showed that the sensors exhibited different responses towards civet coffees and non-civet (control) coffees of different provenance. Principal component analysis (PCA) and Heirarchical cluster analysis (HCA) demonstrated a clearly separated civet coffees from their control beans. The cluster separation among civet coffee samples indicated that geographic origins dictate the aroma and flavor variations in coffee. This remarkable performance of E-nose provides proof that it is an excellent tool for authentication of the provenance of civet coffee and non-civet coffee samples

Nanostructured metal oxide gas sensors, a survey of applications carried out at SENSOR lab, brescia (Italy) in the security and food quality fields

8partially_openopenPonzoni A. ; Comini E. ; Concina I. ; Ferroni M. ; Falasconi M. ; Gobbi E.; Sberveglieri V. ; Sberveglieri G.Ponzoni, Andrea; Comini, Elisabetta; Concina, Isabella; Ferroni, Matteo; Falasconi, Matteo; Gobbi, Emanuela; Sberveglieri, V.; Sberveglieri, Giorgi

functionalized multi wall carbon nanotubes tio2 composites as efficient photoanodes for dye sensitized solar cells

The incorporation of functionalized multi-wall carbon nanotubes into TiO2 mesoporous photoanodes for dye-sensitized solar cells leads to 30% enhancement in photoconversion efficiency of the optimized system

Solvothermal Synthesis, Gas-Sensing Properties, and Solar Cell-Aided Investigation of TiO2-MoOx Nanocrystals

Titania anatase nanocrystals were prepared by sol-gel/solvothermal synthesis in oleic acid at 250 °C, and modified by co-reaction with Mo chloroalkoxide, aimed at investigating the effects on gas-sensing properties induced by tailored nanocrystals surface modification with ultra-thin layers of MoO species. For the lowest Mo concentration, only anatase nanocrystals were obtained, surface modified by a disordered ultra-thin layer of mainly octahedral Mo oxide species. For larger Mo concentrations, early MoO phase segregation occurred. Upon heat treatment up to 500 °C, the sample with the lowest Mo concentration did not feature any Mo oxide phase segregation, and the surface Mo layer was converted to dense octahedral Mo oxide. At larger Mo concentrations all segregated MoO was converted to MoO. The two different materials typologies, depending on the Mo concentration, were used for processing gas-sensing devices and tested toward acetone and carbon monoxide, which gave a greatly enhanced response, for all Mo concentrations, to acetone (two orders of magnitude) and carbon monoxide with respect to pure TiO. For the lowest Mo concentration, dye-sensitized solar cells were also prepared to investigate the influence of anatase surface modification on the electrical transport properties, which showed that the charge transport mainly occurred in the ultra-thin MoO surface layer

Inorganic photocatalytic enhancement : Activated RhB Photodegradation by surface modification of SnO2 Nanocrystals with V2 O5-like species

Ajuts: CSIC/CNR project 2010IT0001 (SYNCAMON), SOLAR project DM19447, VINNOVA Marie Curie Incoming Grant under "Light Energy" project.SnO nanocrystals were prepared by precipitation in dodecylamine at 100 °C, then they were reacted with vanadium chloromethoxide in oleic acid at 250 °C. The resulting materials were heat-treated at various temperatures up to 650 °C for thermal stabilization, chemical purification and for studying the overall structural transformations. From the crossed use of various characterization techniques, it emerged that the as-prepared materials were constituted by cassiterite SnO nanocrystals with a surface modified by isolated V(IV) oxide species. After heat-treatment at 400 °C, the SnO nanocrystals were wrapped by layers composed of vanadium oxide (IV-V mixed oxidation state) and carbon residuals. After heating at 500 °C, only SnO cassiterite nanocrystals were obtained, with a mean size of 2.8 nm and wrapped by only V O-like species. The samples heat-treated at 500 °C were tested as RhB photodegradation catalysts. At 10 M concentration, all RhB was degraded within 1 h of reaction, at a much faster rate than all pure SnO materials reported until now

An Old Material for a New World: Prussian Blue and Its Analogues as Catalysts for Modern Needs

Prussian blue analogues (PBAs) have recently emerged as effective materials in different functional applications, ranging from energy storage to electrochemical water splitting, thence to more “traditional” heterogeneous catalysis. Their versatility is due to their open framework, compositional variety, and fast and efficient internal charge exchange, coupled with a self-healing ability that makes them unique. This review paper presents and discusses the findings of the last decade in the field of the catalytic and photocatalytic application of PBAs in water remediation (via the degradation of organic pollutants and heavy metal removal) and the catalytic oxidation of organics and production or organic intermediates for industrial synthesis. Analysis of the catalytic processes is approached from a critical perspective, highlighting both the achievements of the research community and the limits still affecting this field.Validerad;2024;Nivå 2;2024-05-13 (hanlid);Full text license: CC BYSUPERCA

Functionalised zinc oxide nanowire gas sensors: Enhanced NO2 gas sensor response by chemical modification of nanowire surfaces

Surface coating with an organic self-assembled monolayer (SAM) can enhance surface reactions or the absorption of specific gases and hence improve the response of a metal oxide (MOx) sensor toward particular target gases in the environment. In this study the effect of an adsorbed organic layer on the dynamic response of zinc oxide nanowire gas sensors was investigated. The effect of ZnO surface functionalisation by two different organic molecules, tris(hydroxymethyl)aminomethane (THMA) and dodecanethiol (DT), was studied. The response towards ammonia, nitrous oxide and nitrogen dioxide was investigated for three sensor configurations, namely pure ZnO nanowires, organic-coated ZnO nanowires and ZnO nanowires covered with a sparse layer of organic-coated ZnO nanoparticles. Exposure of the nanowire sensors to the oxidising gas NO2 produced a significant and reproducible response. ZnO and THMA-coated ZnO nanowire sensors both readily detected NO2 down to a concentration in the very low ppm range. Notably, the THMA-coated nanowires consistently displayed a small, enhanced response to NO2 compared to uncoated ZnO nanowire sensors. At the lower concentration levels tested, ZnO nanowire sensors that were coated with THMA-capped ZnO nanoparticles were found to exhibit the greatest enhanced response. ΔR/R was two times greater than that for the as-prepared ZnO nanowire sensors. It is proposed that the ΔR/R enhancement in this case originates from the changes induced in the depletion-layer width of the ZnO nanoparticles that bridge ZnO nanowires resulting from THMA ligand binding to the surface of the particle coating. The heightened response and selectivity to the NO2 target are positive results arising from the coating of these ZnO nanowire sensors with organic-SAM-functionalised ZnO nanoparticles

Materiali Nanostrutturati per la Foto-conversione di CO2

Tra i tentativi per controllare il livello di gas serra (GS), come, per esempio, la quantità di biossido di carbonio (CO2 ) nell’atmosfera, vi è l’utilizzo di tecnologie finalizzate a cattura e utilizzo del carbonio (CUC). Nello studio descritto, l’ossido di zinco (ZnO) e l’ossido di titanio (TiO2 ) sono stati testati prima come candidati per la cattura di CO2 e sua conversione diretta mediata dal solo utilizzo della luce, poi per un processo di fotocatalisi elettro-assistito, mediante l’applicazione di un potenziale elettrico, nell’ottica di un processo di conversione più sostenibile ed economico rispetto alle tecnologie attualmente impiegate

Electronic Noses as Flexible Tools to Assess Food Quality and Safety: Should we Trust Them?

This paper presents three different applications of an electronic nose (EN) based on a metal oxide sensor array, in order to illustrate the broad spectrum of potential uses of the technique in food quality control. The following scenarios are considered: 1) the screening of a typical error that may occur during the processing of tomato pulp, which leads to sensory damage of the product; 2) the detection of microbial contamination by Alicyclobacillus spp. (ACB) affecting soft drinks; and 3) the proof of evidence of extra virgin olive oil fraudulently adulterated with hazelnut oil. In each case, the EN is able to identify the spoiled product by means of the alterations in the pattern of volatile compounds, reconstructed by principal component analysis of the sensor responses