Name: nanostructured ag-zeolite composites as luminescence-based humidity sensors
Uploaded: 2016-11-15T14:00:00.000+00:00
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Description: Watch this Scientific Journal Video about Nanostructured Ag-zeolite Composites as Luminescence-based Humidity Sensors at JoVE.com

The authors gratefully acknowledge financial support from the Belgian Federal government (Belspo through the IAP VI/27 and IAP-7/05 programs), the European Union's Seventh Framework Programme (FP7/2007-2013 under grant agreement no. 310651 SACS), the Flemish government in the form of long-term structural funding "Methusalem" grant METH/08/04 CASAS, the "Strategisch Initiatief Materialen" SoPPoM program, and the Fund for Scientific Research Flanders (FWO) grant G.0349.12. W.B. gratefully acknowledge the chemistry department of the KU Leuven for a FLOF-scholarship. The authors thank UOP Antwerp for the kind donation of zeolite samples and the mechanical workshop of the KU Leuven for helping with the design and construction of the heating/vacuum cell used in this study.

Attenzione: I prodotti chimici e reagenti utilizzati nella presente relazione sono stati maneggiati con cura utilizzando le adeguate protezioni di sicurezza (camici, guanti, occhiali di sicurezza, cappe). Questo studio si occupa della manipolazione di materiali inorganici microporosi (zeoliti con dimensioni che vanno da 1 a 5 micron), quindi una particolare attenzione era rivolta al uso di un&#39;adeguata protezione antipolvere (maschere antipolvere). Si consiglia la consultazione dei dati di sicurezza materiale pertinente (MSDS) dei prodotti chimici e reagenti impiegati in questo lavoro prima dell&#39;uso per una corretta manipolazione e / o lo smaltimento dei rifiuti. 1. Zeolite pre-trattamento <ol><li> Calore pretrattamento NOTA: Pre-trattare i materiali zeolite prima dell&#39;uso per rimuovere le impurità, come impurità organiche, che potrebbero ostacolare la formazione di cluster argento e luminescenza. <ol><li> Pesare 10 g di (Na) zeoliti commerciali LTA (zeoliti commerciali LTA contengono sodio come ioni contro-bilanciamento nei loro quadri) e deposedersi omogeneamente su un vassoio di porcellana. </li><li> Riscaldare la polvere di zeolite notte in un forno a muffola a 450 ° C con una rampa di temperatura di 5 ° C / min con intervalli di 1 ora a 80 ° C e 110 ° C per evitare danni zeolite struttura. </li><li> Rimuovere il materiale di zeolite dal forno e lasciate raffreddare fino a temperatura ambiente in condizioni ambientali. </li></ol></li><li> la selezione delle dimensioni delle particelle di zeolite NOTA: Questo genererà una granulometria più uniforme dei materiali di partenza zeolite, necessario per la creazione di un film omogeneo. Questo passaggio rimuove anche grandi particelle amorfe, che sono spesso presenti nelle zeoliti di produzione industriale. <ol><li> Pesare 10 g di LTA commerciale (Na) e sospende in 1 L di acqua deionizzata. </li><li> Sonicare la sospensione per 1 ora, scuotendo vigorosamente la sospensione da parte ogni 10 min. </li><li> Versare la sospensione in un cilindro Atterberg (1 L) per 30 min. Particelle inferiori a 10 micron di dimensionerimangono in sospensione, ma le particelle più grandi precipitano. </li><li> Decantare la sospensione e recuperare la polvere per filtrazione usando un imbuto Buchner. Lavare la polvere recuperata tre volte con acqua deionizzata. </li><li> Il calore trattare la polvere come descritto al punto 1.1.2. </li></ol></li></ol> 2. Preparazione di luminescenti LTA (Na) -AG Zeolite Compositi <ol><li> Sintesi di argento luminescenti scambiata LTA zeolite [LTA (Na) -AG] come materiale di riferimento <ol><li> Disciogliere 74,8 mg di nitrato d&#39;argento in 200 ml di acqua deionizzata in un 250 ml polipropilene ad alta densità (HDPE). </li><li> Pesare 1 g del campione pretrattato LTA (Na) e sospensione nella soluzione di nitrato d&#39;argento. </li><li> Lasciare la muffola HDPE agitazione durante la notte in un end-over-end forno agitatore a temperatura ambiente. </li><li> Filtrare la sospensione con un imbuto Büchner e lavare la polvere di zeolite 3 volte con acqua deionizzata. </li><li> Riscaldare la polvere recuperata in una muffola a 450 ° C, utilizzando la stessa procedura descritta al punto 1.1.2. </li><li> Raffreddare il campione e collocarlo in un essiccatore con umidità controllata (98% di umidità relativa). Controllo dell&#39;umidità relativa ponendo una soluzione satura di solfato di potassio dentro l&#39;essiccatore. 15 </li><li> Misurare la eccitazione ed emissione spettri dei campioni (a diverse lunghezze d&#39;onda) utilizzando uno spettrofluorometro nonché la loro efficienza quantica esterna. <ol><li> Misurare due piazzole di eccitazione-emissione dimensionali ponendo il campione in una cuvetta di quarzo percorso 1 mm. Raccogliere spettri di emissione a partire dal 30 nm di lunghezza d&#39;onda di eccitazione di sopra del fino a 800 nm con 5 passi nm e un tempo di permanenza di 0,1 sec. </li><li> Applicare correzioni utilizzando il software dello strumento per l&#39;intensità della lampada e la lunghezza d&#39;onda di rilevamento carico del percorso di emissione dei dati grezzi. Inoltre, utilizzare un filtro passa lungo per evitare il secondo picco di ordine nelle due lotti dimensionali. </li><li> Eseguire effici quantisticamisure renza utilizzando una sfera di integrazione attaccato al spettrofluorimetro. 16 Registrare la scansione di emissione da 240 nm a 600 nm sia per il campione di zeolite e BaSO 4 riferimento utilizzando 260 nm come lunghezza d&#39;onda di eccitazione, e quindi calcolare l&#39;efficienza quantica utilizzando il software dello strumento. </li></ol></li></ol></li></ol> 3. Preparazione di luminescenti [LTA (Li) -AG] Zeolite Composites <ol><li> Sintesi di zeolite scambiata parzialmente litio LTA [LTA (Li)] Nota: La procedura seguita per la fabbricazione di LTA (LI) zeoliti scambiate in parte è stato adattato dal rapporto Yahiro e collaboratori 17. <ol><li> Sciogliere 17,2 g di nitrato di litio a 2,5 L di acqua deionizzata. </li><li> Versare 0,5 L della soluzione di nitrato di litio in un pallone da 1 L HDPE. </li><li> Pesare 3 g di LTA (Na) zeolite pre-trattata e sospende nel pallone HDPE contenente la soluzione di nitrato di litio. </li><li> Agitare la beuta con un fine-over-end shaker forno a temperatura ambiente per una notte. </li><li> Filtrare la sospensione con un imbuto Büchner e lavare la polvere recuperata 3 volte con acqua deionizzata. </li><li> Eseguire lo scambio di litio <ol><li> Aggiungere 0,5 L di soluzione di nitrato di litio fresco (3.1.1) in un matraccio HDPE 1 L contenente la polvere recuperata dalla fase di filtrazione (3.1.5). </li><li> Ripetere i punti 3.1.4 e 3.1.5. </li><li> Ripetere i punti 3.1.6.1 e 3.1.6.2 altre 4 volte. </li></ol></li><li> Recuperare la polvere di zeolite e riscaldare in un forno a muffola a 450 ° C per una notte con una rampa di temperatura di 5 ° C / min con intervalli di 1 ora a 80 ° C e 110 ° C. </li></ol></li><li> Sintesi di luminescenti [LTA (LI) -AG] zeoliti <ol><li> Disciogliere 74,8 mg di nitrato d&#39;argento in 200 ml di acqua deionizzata utilizzando un flacone HDPE 250 ml. </li><li> Pesare 1 g del parzialmente scambiate litio LTA zeolite [LTA (Li)] e sospenderlo nella soluzione di nitrato d&#39;argento (3.2.1). </li><li> Agitare il fl HDPEchiedere utilizzando un forno agitatore end-over-end a temperatura ambiente per una notte. </li><li> Filtrare la sospensione con un imbuto Büchner e lavare la zeolite polvere recuperata 3 volte con acqua deionizzata. </li><li> Calore-trattare la polvere in un forno a muffola a 450 ° C per una notte con una rampa di temperatura di 5 ° C / min con intervalli di 1 ora a 80 ° C e 110 ° C. </li><li> Raffreddare il campione in condizioni di umidità controllata utilizzando un essiccatore contenente una soluzione satura di solfato di potassio all&#39;interno (umidità relativa 98%). 15 </li><li> Misurare la eccitazione ed emissione spettri dei campioni e la loro efficienza quantica esterna seguendo la procedura descritta nel passaggio 2.1.7. </li><li> Effettuare analisi termogravimetrica (TGA) per determinare il contenuto di acqua nel campione a diverse temperature. 1 Brevemente, posizionare 30 a 50 mg del campione preparato su un portacampioni platino e caricarlo nel dispositivo TGA. Misurare la perdita di peso da 50° C fino a 600 ° C con un tasso di calore di 5 ° C / min, sotto flusso di azoto (90 ml / min). </li></ol></li></ol> 4. Realizzazione di un LTA (Li) -AG / polietilenimmina (PEI) Composito depositato Film per umidità Sensing Applications Nota: La procedura di deposizione utilizzata in questo rapporto è stato modificato e adattato da riferimento 18. <ol><li> LTA (Li) -AG preparazione sospensione colloidale. <ol><li> Diluire 1 ml di 50% in peso soluzione commerciale PEI a 100 ml con acqua deionizzata. </li><li> Pesare 250 mg del luminescenti LTA (Li) materiale -AG. </li><li> Mescolare la zeolite e soluzione PEI insieme in un flacone in HDPE da 125 ml e agitare vigorosamente la sospensione. </li><li> Posizionare il flacone in un bagno sonicatore 40 kHz a temperatura ambiente per una notte, per ottenere una sospensione omogenea. </li><li> Versare la sospensione LTA (Li) -AG / PEI in un flacone spray. </li></ol></li><li> Deposizione di un film LTA (Li) -ag / PEI su una lastra di quarzo per il sensore protla produzione oType. <ol><li> Pulire una lastra di quarzo da risciacquo con acqua deionizzata e acetone consecutivamente, prima della deposizione di film. Essiccare le piastre pulite in un forno a 80 ° C per 1 ora. </li><li> Spruzzare ricoprire la piastra di quarzo da un lato, posizionando la piastra di quarzo orizzontalmente su un foglio di alluminio e spruzzare tre volte (3 sec ogni volta) da una distanza di circa 20 cm. Posizionare la piastra rivestita all&#39;interno di un forno di essiccazione a 50 ° C per 30 min. </li><li> Ripetere il punto 4.2.2 altre 4 volte fino a quando il film è uniforme. </li></ol></li><li> Idratazione / disidratazione del prototipo di sensore. <ol><li> Posizionare la piastra di quarzo rivestito nel vano campione di una cella di riscaldamento / vuoto in-house. 5 </li><li> Chiudere la camera del campione della cella inserendo una lastra di quarzo pulito in combinazione con un anello di gomma sulla parte superiore della piastra rivestita e sigillare la cella utilizzando un tappo di Teflon e viti come illustrato nella figura 2. </li><li> Applicare alto vuoto, noiing una pressione inferiore a 10 -3 mbar, alla notte cellula per disidratare il campione. </li><li> monitorare visivamente i cambiamenti di colore di emissione (nella regione visibile) del film depositato utilizzando una lampada UV. </li><li> Aprire la camera del campione di monitorare i cambiamenti di colore di emissione, nella regione del visibile, sulla reidratazione del film utilizzando una lampada UV. </li><li> Ripetere il ciclo più volte a partire dal punto 4.3.2 a 4.3.5 per testare la reversibilità del film LTA (Li) -AG / PEI. </li></ol></li></ol>

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The authors have nothing to disclose.

A simple device to demonstrate the proof of concept of using LTA(Li)-Ag as a luminescence based humidity sensor was produced by spray coating the LTA(Li)-Ag powder suspended in a PEI solution onto a quartz plate. The PEI solution produces a polymer layer with homogenous thickness when the water is evaporated. The polymer-zeolite composite layer displays similar luminescent properties as that of the zeolite in powder form. The PEI/LTA(Li)-Ag zeolite composite displays the expected water-responsive luminescent properties, whose emission color changes upon variations in the water content present in the composite at relatively low humidity scale. 
Replacing Na with Li ions in LTA zeolites (calculated exchange rate 33%) has a notable impact on the self-assembly and stabilization of luminescent silver clusters in the LTA(Li) scaffolds leading to unique optical properties. The EQE of LTA(Li)-Ag as compared to LTA(Na)-Ag samples is enhanced by more than one order of magnitude. Moreover, the emission colors displayed by the LTA(Li)-Ag samples have a water-dependence, providing a potential application of the samples as luminescence based humidity sensors. 
We have thus demonstrated an easy method to fabricate a luminescent film-like humidity sensor through which changes in hydration levels can be visually monitored simply by using a UV lamp. The availability of the raw materials, the direct visualization of the color changes correlated with humidity content, the photo-stability of the films, and the relative ease of fabricating cost-effective devices make these luminescent materials potential candidates to compete with state-of-the-art humidity sensors based upon electrical responses. The procedure described in this report could also be applied and extended to different substrates, at different micro and macro scales, to make the sensor more flexible. Additionally, several critical steps during the fabrication of Ag-zeolites, which play an important role in determining the final optical properties of such materials, were discussed in this protocol. For instance, the pre-cleaning of the raw zeolite material leads to the removal of optical and chemical impurities, as well as to homogenous zeolite crystal size distribution. This is crucial for the incorporation of zeolites into functional devices. One limitation of the present methodology is the restriction on the use of thin film sensors beyond 75 &#176;C. This is mainly due to the decomposition of the PEI polymer, rather than to the degradation of the LTA(Li)-Ag zeolites, which can withstand up to 500 &#176;C. The use of heat-resistant polymers, such as polyvinyl alcohol, could expand the temperature range up to 200 &#176;C. We expect that further investigations will be directed to the development of methodologies for the synthesis of nanostructured Ag-zeolite composites with (multi)functional properties and finally to the design of advanced sensor prototypes.

Piccolo sub-nanometrica grappoli d&#39;argento oligoatomic formati da auto-assemblaggio in matrici zeolite ristretti visualizzare le proprietà ottiche uniche. 1-5 Tali composti d&#39;argento-zeolite hanno alta chimica e la foto-stabilità. Tuttavia, le proprietà di fotoluminescenza sono fortemente dipendenti l&#39;ambiente locale dei cluster argento. Le condizioni ambientali che influenzano le caratteristiche ottiche in compositi argento zeolite possono essere suddivisi in proprietà intrinseche ed estrinseche. Proprietà intrinseche sono legati alla topologia zeolite, il tipo di ioni di controbilanciamento, e il carico di argento. 1 D&#39;altra parte, proprietà estrinseche sono associate ai cambiamenti post-sintetici, quali la presenza di adsorbati o molecole di acqua nella zeolite cavità. 3,4 quest&#39;ultima proprietà conferiscono ad argento-zeolite Panelli la capacità di rispondere otticamente a stimoli esterni, quali variazioni di umidità all&#39;interno della zeolite scaffold 6-8 </sup&gt; o la presenza di gas determinati; pertanto il loro uso come sensori vapore acqueo e gas è stato suggerito. 9,10 In un recente studio abbiamo dimostrato che la risposta ottica di Ag-zeoliti di umidità non solo è correlato ai cambiamenti nell&#39;assorbimento o tempra della loro emissione, ma anche alla comparsa di diversi colori di emissione rispetto al loro contenuto di acqua. 5 La stabilizzazione dei cluster d&#39;argento in parte Li scambiati zeoliti LTA portato alla formazione di un materiale di umidità-sensibile in cui le variazioni di scala relativa bassa umidità sono riflesse in un cambio dinamico del colore da blu a emissione verde / giallo in campioni disidratati e idrati, rispettivamente, . Pertanto è stato proposto l&#39;uso di questi materiali come sensori di umidità luminescenza-based. Fino ad oggi, i diversi tipi di materiali come elettroliti, ceramiche, polimeri e compositi nanostrutturati sono stati proposti per il monitoraggio dei cambiamenti di umidità based sulle risposte elettriche e ottiche. 11,12 In questo protocollo dettagliato ci proponiamo di dare prova di una proof-of-concept per l&#39;applicazione delle zeoliti LTA (Li) -AG come sensori di umidità e per ulteriori sviluppi prototipo. Grazie alla versatilità di LTA zeoliti (Li) -ag essere incorporati in diversi substrati, il loro potenziale scalabilità e fabbricazione economica, la progettazione del prototipo potrebbe essere facilitato. 13 Tali sensori potrebbero avere potenziale applicabilità in diversi settori industriali, come ad esempio in agricoltura, così come l&#39;industria automobilistica e della carta. 14

<table><tbody><tr><td>LTA(Na) zeolite</td><td>UOP</td><td>Molsiv adsorbent 4A</td><td></td></tr><tr><td>Silver nitrate</td><td>Sigma Aldrich</td><td>209139</td><td>&amp;ge;99.0%</td></tr><tr><td>Lithium nitrate</td><td>Sigma Aldrich</td><td>62574</td><td>&amp;ge;99.0%, calc. on dry substances</td></tr><tr><td>Polyethyleneimine solution</td><td>Sigma Aldrich</td><td>3880</td><td>~50% H&lt;sub&gt;2&lt;/sub&gt;O</td></tr><tr><td>Scanning electron microscope (SEM)</td><td>JEOL</td><td>JSM-6010LV</td><td></td></tr><tr><td>Thermogravimetric analyzer</td><td>TA instruments</td><td>Q500</td><td></td></tr><tr><td>Spectrofluorimeter</td><td>Edinburgh instruments</td><td>FLS980-s</td><td></td></tr><tr><td>Integrating sphere</td><td>Labsphere</td><td>4P-GPS-033-SL</td><td></td></tr></tbody></table>

nanostructured ag-zeolite composites as luminescence-based humidity sensors

Small silver clusters confined inside zeolite matrices have recently emerged as a novel type of highly luminescent materials. Their emission has high external quantum efficiencies (EQE) and spans the whole visible spectrum. It has been recently reported that the UV excited luminescence of partially Li-exchanged sodium Linde type A zeolites [LTA(Na)] containing luminescent silver clusters can be controlled by adjusting the water content of the zeolite. These samples showed a dynamic change in their emission color from blue to green and yellow upon an increase of the hydration level of the zeolite, showing the great potential that these materials can have as luminescence-based humidity sensors at the macro and micro scale. Here, we describe the detailed procedure to fabricate a humidity sensor prototype using silver-exchanged zeolite composites. The sensor is produced by suspending the luminescent Ag-zeolites in an aqueous solution of polyethylenimine (PEI) to subsequently deposit a film of the material onto a quartz plate. The coated plate is subjected to several hydration/dehydration cycles to show the functionality of the sensing film.

SEM micrografie della zeolite LTA-Ag sono stati registrati dopo la fase di scambio cationico e trattamento termico. Successivamente la fotoluminescenza bidimensionali (2D) di eccitazione / trame di emissione sono stati misurati sia per il idratata LTA (Na) -AG e LTA (Li) zeoliti -AG (Figura 1). Analisi elementare è stata eseguita sul XPS Ag scambiate zeoliti per determinare la loro composizione chimica. L&#39;analisi mostra che lo scambio d&#39;argento su LTA (Na) e LTA zeoliti (Li) è molto stretto con una percentuale in peso di argento del 19,6% in peso e 21,5% in peso, rispettivamente. La differenza in percentuale in peso potrebbe essere ascritta al peso atomico inferiore atomi Li. Inoltre l&#39;analisi elementare ha anche mostrato che, dopo lo scambio Li 33% di Na è sostituito. Lo scambio cationico e la successiva fase di trattamento termico eseguito sui campioni non sembrano influenzare la struttura dei cristalli LTA, come dimostrato da SEM. Inoltre, la formazione di argento ingrandisci nanoparticles sulla superficie dei cristalli di zeolite non era visualizzate. Le proprietà luminescenti in gran parte differiscono sia la LTA (Li) -AG e campioni LTA (Na) -AG nel loro stato idratato. Incorporando litio nell&#39;ambito zeolite come catione controbilanciamento, uno spostamento blu in eccitazione massima si verifica da 370 nm a 260 nm, per LTA (Na) -ag e LTA (Li) -ag rispettivamente. In contrasto massimo di emissione subisce un piccolo spostamento rossa da 550 al 565 nm aggiungendo Li nel sistema. La più grande differenza tra questi campioni si osserva nelle loro efficienza quantica esterna (EQE). LTA (Na) zeoliti -ag possiedono un EQE di circa 4% al massimo di eccitazione (370 nm), mentre la EQE per LTA (Li) zeoliti -ag raggiunge 62% (quando eccitato a 260 nm). Questo si traduce in un giallo brillante Emitting polvere sotto 254 nm UV illuminazione. Le proprietà luminescenti del campione LTA (Li) -ag dipendono anche il contenuto di acqua delsistema. Questo è stato dimostrato da una combinazione di TGA e temperatura dipendente esperimenti luminescenza, TGA correla la temperatura al livello di idratazione della zeolite. Inoltre, la temperatura sia indirettamente correlata al colore di emissione mostrata dal campione LTA (Li) -ag utilizzando una cella di riscaldamento interno (figura 2). Le variazioni di colore dal giallo delle emissioni oltre verde al blu, quando si rimuove l&#39;acqua dal sistema di LTA (Li) -AG. Il EQE scende costantemente dal 62% (stato idratato) al 21% (stato di disidratazione). A causa del comportamento reattivo in acqua di LTA (Li) -ag, questo materiale è stato usato per fabbricare un prototipo di sensore di umidità luminescenza basato sospendendo la polvere in una soluzione PEI e successivamente spruzzare rivestimento composito su una piastra di quarzo. Immagini (sotto la luce del giorno e UV illuminazione) e SEM micrografie del film LTA (Li) -AG / PEI spruzzo rivestite vengono visualizzati in figura 3. Abbiamo osservato che da USI<html> ng questa procedura di rivestimento, uno strato relativamente omogenea del composito polimero zeolite in termini di luminescenza è stata ottenuta. La micrografia SEM mostra che i cristalli di zeolite non sono alterati dalla procedura di rivestimento. Utilizzando un riscaldamento / cella a vuoto in casa è stato anche dimostrato che il film polimerico-zeolite mantiene le proprietà reattivo in acqua che sono stati osservati nella zeolite in forma di polvere. <img alt="Figura 1" src="/files/ftp_upload/54674/54674fig1.jpg" /> Figura 1: foto SEM e proprietà luminescenti dell&#39;argento scambiati zeoliti LTA micrografie SEM e 2D trame eccitazione-emissione di LTA (Na) -ag (a, b) e LTA (Li) -ag (c, d).. Gli inserti nelle trame di eccitazione-emissione 2D lo schermo a colori di emissione simulati dei campioni in diverse lunghezze d&#39;onda di eccitazione (254, 300, 366 e 450 nm).<html> OAD / 54674 / 54674fig1large.jpg &quot;target =&quot; _ blank &quot;&gt; Clicca qui per vedere una versione più grande di questa figura. <img alt="figura 2" src="/files/ftp_upload/54674/54674fig2.jpg" /> Figura 2: Effetto del livello di idratazione sulle proprietà luminescenti di LTA (Li) -AG. a) Rappresentazione schematica della cella di riscaldamento / vuoto internamente impiegato in questo studio b) terreno TGA per la LTA (Li) -ag campione c) spettri di emissione normalizzato (su 260 nm eccitazione) della LTA (Li).. - campione Ag misurata a diverse temperature. d) Schema di visualizzazione del cambiamento di colore emissione di campioni reali rispetto al contenuto di acqua. <a href="https://ecsource-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/54674/54674fig2large.jpg" target="_blank">Si prega di cliccare qui per vedere una versione più grande di questa figura.</a> ftp_upload / 54674 / 54674fig3.jpg &quot;/&gt; Figura 3: sensore di umidità luminescente sulla base di un composito LTA (Li) -AG / PEI. a) Le fotografie della piastra rivestita sotto illuminazione diurna. (B, c) Immagini di piastra disidratata e idratata rivestito sotto 254 nm UV-irradiazione di luce rispettivamente. D) Micrografia SEM del film depositato mostra la distribuzione dei LTA (Li) cristalli -ag sulla superficie del quarzo. L&#39;inserto mostra un ingrandimento di un&#39;area selezionata della microfotografia SEM originale. E) Emissione Maxima dei idratata e disidratato PEI / LTA (Li) -AG zeolite composito, durante 10 idratazione / disidratazione cicli utilizzando 260 nm come eccitazione lunghezza d&#39;onda. F) trama visualizzare l&#39;emissione profili Maxima comportamento del PEI / LTA (Li) -AG zeolite composito dopo cicli di 10 idratazione / disidratazione. <a href="https://ecsource-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/54674/54674fig3large.jpg" target="_blank">clicca qui a vi</a>ew una versione più grande di questa figura.

Watch this Scientific Journal Video about Nanostructured Ag-zeolite Composites as Luminescence-based Humidity Sensors at JoVE.com

Nanostructured Ag-zeolite Composites as Luminescence-based Humidity Sensors

A protocol for the synthesis of moisture-responsive luminescent Ag-zeolite composites is described in this report.

Compositi nanostrutturati Ag-zeolite come Sensori di umidità a base di luminescenza

Small silver clusters confined inside zeolite matrices have recently emerged as a novel type of highly luminescent materials. Their emission has high ...

nanostructured-ag-zeolite-composites-as-luminescence-based-humidity

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10.1K Views.  KU Leuven. A protocol for the synthesis of moisture-responsive luminescent Ag-zeolite composites is described in this report.

Video: Nanostructured Ag-zeolite Composites as Luminescence-based Humidity Sensors

Preparation and Use of Photocatalytically Active Segmented Ag|ZnO and Coaxial TiO2-Ag Nanowires Made by Templated Electrodeposition

Photocatalytically active nanostructures require a large specific surface area with the presence of many catalytically active sites for the oxidation and reduction half reactions, and fast electron (hole) diffusion and charge separation. Nanowires present suitable architectures to meet these requirements. Axially segmented Ag|ZnO and radially segmented (coaxial) TiO2-Ag nanowires with a diameter of 200 nm and a length of 6-20 &#181;m were made by templated electrodeposition within the pores of polycarbonate track-etched (PCTE) or anodized aluminum oxide (AAO) membranes, respectively. In the photocatalytic experiments, the ZnO and TiO2 phases acted as photoanodes, and Ag as cathode. No external circuit is needed to connect both electrodes, which is a key advantage over conventional photo-electrochemical cells. For making segmented Ag|ZnO nanowires, the Ag salt electrolyte was replaced after formation of the Ag segment to form a ZnO segment attached to the Ag segment. For making coaxial TiO2-Ag nanowires, a TiO2 gel was first formed by the electrochemically induced sol-gel method. Drying and thermal annealing of the as-formed TiO2 gel resulted in the formation of crystalline TiO2 nanotubes. A subsequent Ag electrodeposition step inside the TiO2 nanotubes resulted in formation of coaxial TiO2-Ag nanowires. Due to the combination of an n-type semiconductor (ZnO or TiO2) and a metal (Ag) within the same nanowire, a Schottky barrier was created at the interface between the phases. To demonstrate the photocatalytic activity of these nanowires, the Ag|ZnO nanowires were used in a photocatalytic experiment in which H2 gas was detected upon UV illumination of the nanowires dispersed in a methanol/water mixture. After 17 min&#160;of illumination, approximately 0.2 vol% H2 gas was detected from a suspension of ~0.1 g of Ag|ZnO nanowires in a 50 ml 80 vol% aqueous methanol solution.

Preparation and Use of Photocatalytically Active Segmented Ag|ZnO and Coaxial TiO2-Ag Nanowires Made by Templated Electrodeposition

Procedures are outlined to prepare segmented and coaxial nanowires via templated electrodeposition in nanopores. As examples, segmented nanowires consisting of Ag and ZnO segments, and coaxial nanowires consisting of a TiO2 shell and a Ag core were made. The nanowires were used in photocatalytic hydrogen formation experiments.

Preparazione e utilizzo di fotocataliticamente attivo segmentata Ag | ZnO e coassiale TiO<sub&gt; 2</sub&gt;-Ag Nanowires Made by Templated Electrodeposition

Photocatalytically active nanostructures require a large specific surface area with the presence of many catalytically active sites for the oxidation and ...

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Synthesis of Zeolites Using the ADOR (Assembly-Disassembly-Organization-Reassembly) Route

Zeolites are an important class of materials that have wide ranging applications such as heterogeneous catalysts and adsorbents which are dependent on their framework topology. For new applications or improvements to existing ones, new zeolites with novel pore systems are desirable. We demonstrate a method for the synthesis of novel zeolites using the ADOR route. ADOR is an acronym for Assembly, Disassembly, Organization and Reassembly. This synthetic route takes advantage of the assembly of a relatively poorly stable that which can be selectively disassembled into a layered material. The resulting layered intermediate can then be organized in different manners by careful chemical manipulation and then reassembled into zeolites with new topologies. By carefully controlling the organization step of the synthetic pathway, new zeolites with never before seen topologies are capable of being synthesized. The structures of these new zeolites are confirmed using powder X-ray diffraction and further characterized by nitrogen adsorption and scanning electron microscopy. This new synthetic pathway for zeolites demonstrates its capability to produce novel frameworks that have never been prepared by traditional zeolite synthesis techniques.

Synthesis of Zeolites Using the ADOR Assembly-Disassembly-Organization-Reassembly Route

A protocol for the preparation of novel zeolites by the ADOR (Assembly-Disassembly-Organization-Reassembly) synthetic route is presented.

Sintesi di zeoliti Uso del ADOR (Assembly-smontaggio-Organizzazione-riassemblaggio) Percorso

Zeolites are an important class of materials that have wide ranging applications such as heterogeneous catalysts and adsorbents which are dependent on ...

Chimica

Detection and Recovery of Palladium, Gold and Cobalt Metals from the Urban Mine Using Novel Sensors/Adsorbents Designated with Nanoscale Wagon-wheel-shaped Pores

Developing low-cost, efficient processes for recovering and recycling palladium, gold and cobalt metals from urban mine remains a significant challenge in industrialized countries. Here, the development of optical mesosensors/adsorbents (MSAs) for efficient recognition and selective recovery of Pd(II), Au(III), and Co(II) from urban mine was achieved. A simple, general method for preparing MSAs based on using high-order mesoporous monolithic scaffolds was described. Hierarchical cubic Ia3d wagon-wheel-shaped MSAs were fabricated by anchoring chelating agents (colorants) into three-dimensional pores and micrometric particle surfaces of the mesoporous monolithic scaffolds. Findings show, for the first time, evidence of controlled optical recognition of Pd(II), Au(III), and Co(II) ions and a highly selective system for recovery of Pd(II) ions (up to ~95%) in ores and industrial wastes. Furthermore, the controlled assessment processes described herein involve evaluation of intrinsic properties (e.g., visual signal change, long-term stability, adsorption efficiency, extraordinary sensitivity, selectivity, and reusability); thus, expensive, sophisticated instruments are not required. Results show evidence that MSAs will attract worldwide attention as a promising technological means of recovering and recycling palladium, gold and cobalt metals.

Because of the importance and extensive use of palladium, gold and cobalt metals in high-technology equipment, their recovery and recycling constitute an important industrial challenge. The metal recovery system described herein is a simple, low-cost means for the effective detection, removal, and recovery of these metals from the urban mine.

Rilevamento e recupero di palladio, oro e metalli di cobalto dalla miniera urbana Utilizzando novelli Sensori / Adsorbenti designate con nanoscala Wagon a forma di ruote pori

Developing low-cost, efficient processes for recovering and recycling palladium, gold and cobalt metals from urban mine remains a significant challenge in ...

Iridium Oxide-reduced Graphene Oxide Nanohybrid Thin Film Modified Screen-printed Electrodes as Disposable Electrochemical Paper Microfluidic pH Sensors

A facile, controllable, inexpensive and green electrochemical synthesis of IrO2-graphene nanohybrid thin films is developed to fabricate an easy-to-use integrated paper microfluidic electrochemical pH sensor for resource-limited settings. Taking advantages from both pH meters and strips, the pH sensing platform is composed of hydrophobic barrier-patterned paper micropad (&#181;PAD) using polydimethylsiloxane (PDMS), screen-printed electrode (SPE) modified with IrO2-graphene films and molded acrylonitrile butadiene styrene (ABS) plastic holder. Repetitive cathodic potential cycling was employed for graphene oxide (GO) reduction which can completely remove electrochemically unstable oxygenated groups and generate a 2D defect-free homogeneous graphene thin film with excellent stability and electronic properties. A uniform and smooth IrO2 film in nanoscale grain size is anodically electrodeposited onto the graphene film, without any observable cracks. The resulting IrO2-RGO electrode showed slightly super-Nernstian responses from pH 2-12 in Britton-Robinson (B-R) buffers with good linearity, small hysteresis, low response time and reproducibility in different buffers, as well as low sensitivities to different interfering ionic species and dissolved oxygen. A simple portable digital pH meter is fabricated, whose signal is measured with a multimeter, using high input-impedance operational amplifier and consumer batteries. The pH values measured with the portable electrochemical paper-microfluidic pH sensors were consistent with those measured using a commercial laboratory pH meter with a glass electrode.

The study demonstrates the growth of iridium oxide-reduced graphene oxide (IrO2-RGO) nanohybrid thin films on irregular and rough screen-printed carbon substrate through a green electrochemical synthesis, and their implementation as a pH sensor with a patterned paper-fluidic platform.

Grafene ossido nanoibrido film sottile elettrodi serigrafati Iridium ossido-riduzione modificato come usa e getta di carta elettrochimica microfluidici pH Sensori

A facile, controllable, inexpensive and green electrochemical synthesis of IrO2-graphene nanohybrid thin films is developed to fabricate an easy-to-use ...

Adsorption Device Based on a Langatate Crystal Microbalance for High Temperature High Pressure Gas Adsorption in Zeolite H-ZSM-5

We present a high-temperature and high-pressure gas adsorption measurement device based on a high-frequency oscillating microbalance (5 MHz langatate crystal microbalance, LCM) and its use for gas adsorption measurements in zeolite H-ZSM-5. Prior to the adsorption measurements, zeolite H-ZSM-5 crystals were synthesized on the gold electrode in the center of the LCM, without covering the connection points of the gold electrodes to the oscillator, by the steam-assisted crystallization (SAC) method, so that the zeolite crystals remain attached to the oscillating microbalance while keeping good electroconductivity of the LCM during the adsorption measurements. Compared to a conventional quartz crystal microbalance (QCM) which is limited to temperatures below 80 &#176;C, the LCM can realize the adsorption measurements in principle at temperatures as high as 200-300 &#176;C (i.e., at or close to the reaction temperature of the target application of one-stage DME synthesis from the synthesis gas), owing to the absence of crystalline-phase transitions up to its melting point (1,470 &#176;C). The system was applied to investigate the adsorption of CO2, H2O, methanol and dimethyl ether (DME), each in the gas phase, on zeolite H-ZSM-5 in the temperature and pressure range of 50-150 &#176;C and 0-18 bar, respectively. The results showed that the adsorption isotherms of these gases in H-ZSM-5 can be well fitted by Langmuir-type adsorption isotherms. Furthermore, the determined adsorption parameters, i.e., adsorption capacities, adsorption enthalpies, and adsorption entropies, compare well to literature data. In this work, the results for CO2 are shown as an example.

A protocol for high-temperature and high-pressure gas adsorption measurements on zeolite H-ZSM-5 using an adsorption measurement device based on a langatate crystal microbalance is presented. Prior to the adsorption measurements, the synthesis of zeolite H-ZSM-5 on the langatate crystal microbalance sensor by the steam-assisted crystallization (SAC) method is demonstrated.

Dispositivo adsorbimento Sulla base di un Langatate cristallo Microbilancia per ALTA TEMPERATURA ALTA PRESSIONE adsorbimento di gas a Zeolite H-ZSM-5

We present a high-temperature and high-pressure gas adsorption measurement device based on a high-frequency oscillating microbalance (5 MHz langatate ...

TiO2-coated Hollow Glass Microspheres with Superhydrophobic and High IR-reflective Properties Synthesized by a Soft-chemistry Method

This manuscript proposes a soft-chemistry method to develop superhydrophobic and highly IR-reflective hollow glass microspheres (HGM). The anatase TiO2 and a superhydrophobic agent were coated on the HGM surface in one step. TBT and PFOTES were selected as the Ti source and the superhydrophobic agent, respectively. They were both coated on the HGM, and after the hydrothermal process, the TBT turned to anatase TiO2. In this way, a PFOTES/TiO2-coated HGM (MCHGM) was prepared. For comparison, PFOTES single-coated HGM (F-SCHGM) and TiO2 single-coated HGM (Ti-SCHGM) were synthesized as well. The PFOTES and TiO2 coatings on the HGM surface were demonstrated through X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive detector (EDS) characterizations. The MCHGM showed a higher contact angle (153&#176;) but a lower sliding angle (16&#176;) than F-SCHGM, with a contact angle of 141.2&#176; and a sliding angle of 67&#176;. In addition, both Ti-SCHGM and MCHGM displayed similar IR reflectivity values, which were about 5.8% higher than the original HGM and F-SCHGM. Also, the PFOTES coating barely changed the thermal conductivity. Therefore, F-SCHGM, with a thermal conductivity of 0.0479 W/(m&#183;K), was quite like the original HGM, which was 0.0475 W/(m&#183;K). MCHGM and Ti-SCHGM were also similar. Their thermal conductivity values were 0.0543 W/(m&#183;K) and 0.0543 W/(m&#183;K), respectively. The TiO2 coating slightly increased the thermal conductivity, but with the increase in reflectivity, the overall heat-insulation property was enhanced. Finally, since the IR-reflecting property is provided by the HGM coating, if the coating is fouled, the reflectivity decreases. Therefore, with the superhydrophobic coating, the surface is protected from fouling, and its lifetime is also prolonged.

TiO2-coated Hollow Glass Microspheres with Superhydrophobic and High IR-reflective Properties Synthesized by a Soft-chemistry Method

This manuscript proposes a soft-chemistry method to synthesize superhydrophobic, TiO2-coated hollow glass microspheres (HGM) with high IR-reflective properties.

TiO<sub&gt; 2</sub&gt; Rivestiti microsfere cave di vetro con proprietà superidrofobiche e High IR-riflettenti sintetizzato da un metodo Soft-chimica

This manuscript proposes a soft-chemistry method to develop superhydrophobic and highly IR-reflective hollow glass microspheres (HGM). The anatase TiO2 ...

Aerosol-assisted Chemical Vapor Deposition of Metal Oxide Structures: Zinc Oxide Rods

Whilst columnar zinc oxide (ZnO) structures in the form of rods or wires have been synthesized previously by different liquid- or vapor-phase routes, their high cost production and/or incompatibility with microfabrication technologies, due to the use of pre-deposited catalyst-seeds and/or high processing temperatures exceeding 900 &#176;C, represent a drawback for a widespread use of these methods. Here, however, we report the synthesis of ZnO rods via a non-catalyzed vapor-solid mechanism enabled by using an aerosol-assisted chemical vapor deposition (CVD) method at 400 &#176;C with zinc chloride (ZnCl2) as the precursor and ethanol as the carrier solvent. This method provides both single-step formation of ZnO rods and the possibility of their direct integration with various substrate types, including silicon, silicon-based micromachined platforms, quartz, or high heat resistant polymers. This potentially facilitates the use of this method at a large-scale, due to its compatibility with state-of-the-art microfabrication processes for device manufacture. This report also describes the properties of these structures (e.g., morphology, crystalline phase, optical band gap, chemical composition, electrical resistance) and validates its gas sensing functionality towards carbon monoxide.

Columnar zinc oxide structures in the form of rods are synthesized via aerosol-assisted chemical vapor deposition without the use of pre-deposited catalyst-seed particles. This method is scalable and compatible with various substrates based on either silicon, quartz or polymers.

Aerosol-assisted Chemical Vapor Deposition di strutture in ossido di metallo: aste di ossido di zinco

Whilst columnar zinc oxide (ZnO) structures in the form of rods or wires have been synthesized previously by different liquid- or vapor-phase routes, ...

Resource Recycling of Red Soil to Synthesize Fe2O3/FAU-type Zeolite Composite Material for Heavy Metal Removal

Heavy metal-polluted water is of great concern to human health and the eco-environment. In situ water remediation techniques enabled by highly efficient adsorption materials are of great importance in these circumstances. Among all the materials used in water remediation, iron-based nanomaterials and porous materials are of great interest, benefiting from their rich redox reactivity and adsorption function. Here, we developed a facile protocol to directly convert the widely spread red soil in south China to fabricate the Fe2O3/faujasite (FAU)-type zeolite composite material. 
The detailed synthesis procedure and synthesis parameters, such as reaction temperature, reaction time, and the Si/Al ratio in the raw materials, have been carefully tuned. The as-synthesized composite materials show good adsorption capacity for typical heavy metal(loid) ions. With 0.001 g/mL Fe2O3/FAU-type zeolite composite material added to different heavy metal(loid)-polluted aqueous solutions (single type of heavy metal(loid) concentration: 1,000 mg/L [ppm]), the adsorption capacity was shown to be 172, 45, 170, 40, 429, 693, 94, and 133 mg/g for Cu (II), Cr (III), Cr (VI), As (III), Cd (II), Pb (II), Zn (II), and Ni (II) removal, respectively, which can be further expanded for heavy metal-polluted water and soil remediation.

Resource Recycling of Red Soil to Synthesize Fe2O3/FAU-type Zeolite Composite Material for Heavy Metal Removal

This article presents a novel and convenient route to synthesize Fe2O3/faujasite (FAU)-type zeolite composite material from red soil. The detailed synthesis parameters have been finely tuned. The obtained composite material can be used for efficient heavy metal-contaminated water remediation, indicating its potential applications in environmental engineering.

Riciclaggio delle risorse della terra rossa per sintetizzare materiale composito di zeolite di tipo Fe2O3/FAU per la rimozione di metalli pesanti

Heavy metal-polluted water is of great concern to human health and the eco-environment. In situ water remediation techniques enabled by highly efficient ...

Ambiente

Luminescence Lifetime Imaging of O2 with a Frequency-Domain-Based Camera System

We describe a method to image dissolved oxygen (O2), in 2D at high spatial (&#60; 50-100 &#181;m) and temporal (&#60; 10 s) resolution. The method employs O2 sensitive luminescent sensor foils (planar optodes) in combination with a specialized camera system for imaging luminescence lifetime in the frequency-domain. Planar optodes are prepared by dissolving the O2-sensitive indicator dye in a polymer and spreading the mixture on a solid support in a defined thickness via knife coating. After evaporation of the solvent, the planar optode is placed in close contact with the sample of interest - here demonstrated with the roots of the aquatic plant Littorella uniflora. The O2 concentration-dependent change in the luminescence lifetime of the indicator dye within the planar optode is imaged via the backside of the transparent carrier foil and aquarium wall using a special camera. This camera measures the luminescence lifetime (&#181;s) via a shift in phase angle between a modulated excitation signal and emission signal. This method is superior to luminescence intensity imaging methods, as the signal is independent of the dye concentration or intensity of the excitation source, and solely relies on the luminescence decay time, which is an intrinsically referenced parameter. Consequently, an additional reference dye or other means of referencing are not needed. We demonstrate the use of the system for macroscopic O2 imaging of plant rhizospheres, but the camera system can also easily be coupled to a microscope.

Luminescence Lifetime Imaging of O2 with a Frequency-Domain-Based Camera System

We describe the use of a novel, frequency-domain luminescence lifetime camera for mapping 2D O2 distributions with optical sensor foils. The camera system and image analysis procedures are described along with the preparation, calibration and application of sensor foils for visualizing the O2 microenvironment in the rhizosphere of aquatic plants.

Luminescenza Lifetime Imaging di O2 con un sistema di telecamere basato su frequenza-dominio

We describe a method to image dissolved oxygen (O2), in 2D at high spatial (&#60; 50-100 &#181;m) and temporal (&#60; 10 s) resolution. The method employs ...

Encapsulating Cytochrome c in Silica Aerogel Nanoarchitectures without Metal Nanoparticles while Retaining Gas-phase Bioactivity

Applications such as sensors, batteries, and fuel cells have been improved through the use of highly porous aerogels when functional compounds are encapsulated within the aerogels. However, few reports on encapsulating proteins within sol&#8211;gels that are processed to form aerogels exist. A procedure for encapsulating cytochrome c (cyt. c) in silica (SiO2) sol-gels that are supercritically processed to form bioaerogels with gas-phase activity for nitric oxide (NO) is presented. Cyt. c is added to a mixed silica sol under controlled protein concentration and buffer strength conditions. The sol mixture is then gelled and the liquid filling the gel pores is replaced through a series of solvent exchanges with liquid carbon dioxide. The carbon dioxide is brought to its critical point and vented off to form dry aerogels with cyt. c encapsulated inside. These bioaerogels are characterized with UV-visible spectroscopy and circular dichroism spectroscopy and can be used to detect the presence of gas-phase nitric oxide. The success of this procedure depends on regulating the cyt. c concentration and the buffer concentration and does not require other components such as metal nanoparticles. It may be possible to encapsulate other proteins using a similar approach making this procedure important for potential future bioanalytical device development.

Encapsulating Cytochrome c in Silica Aerogel Nanoarchitectures without Metal Nanoparticles while Retaining Gas-phase Bioactivity

This procedure describes how to encapsulate cytochrome c (cyt. c) in silica (SiO2) sol-gels, process these gels to form bioaerogels, and use these bioaerogels to rapidly recognize nitric oxide (NO) through a gas-phase reaction. This type of protocol may aid in the future development of biosensors or other bioanalytical devices.

Compositi nanostrutturati Ag-zeolite come Sensori di umidità a base di luminescenza

Riepilogo

Esplora Altri Video

Capitoli in questo video

Preparazione e utilizzo di fotocataliticamente attivo segmentata Ag | ZnO e coassiale TiO

Sintesi di zeoliti Uso del ADOR (Assembly-smontaggio-Organizzazione-riassemblaggio) Percorso

Rilevamento e recupero di palladio, oro e metalli di cobalto dalla miniera urbana Utilizzando novelli Sensori / Adsorbenti designate con nanoscala Wagon a forma di ruote pori

Grafene ossido nanoibrido film sottile elettrodi serigrafati Iridium ossido-riduzione modificato come usa e getta di carta elettrochimica microfluidici pH Sensori

Dispositivo adsorbimento Sulla base di un Langatate cristallo Microbilancia per ALTA TEMPERATURA ALTA PRESSIONE adsorbimento di gas a Zeolite H-ZSM-5

TiO

Aerosol-assisted Chemical Vapor Deposition di strutture in ossido di metallo: aste di ossido di zinco

Riciclaggio delle risorse della terra rossa per sintetizzare materiale composito di zeolite di tipo Fe₂O₃/FAU per la rimozione di metalli pesanti

Luminescenza Lifetime Imaging di O₂ con un sistema di telecamere basato su frequenza-dominio

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