Name: a rapid synthesis method for au, pd, and pt aerogels via direct solution-based reduction
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Yazarlar Stephen Steiner adlı onun ilham ve teknik anlayışlar Aerogel teknolojileri ve Dr Deryn Chu ordu araştırma laboratuvarı-sensörler ve elektron cihazları Müdürlüğü, Dr Christopher Haines, silah araştırma minnettarız, Geliştirme ve Mühendislik Merkezi, ABD Ordusu RDECOM-ARDEC ve Dr. Stephen Bartolucci onların yardım için ABD Ordusu Benet laboratuarlarında. Bu eser desteklenmiştir Amerika Birleşik Devletleri Askeri Akademisi, West Point bir öğretim kalkınma Araştırma Fonu Hibe tarafından.

Dikkat: tüm ilgili güvenlik bilgi formları (SDS) kullanmadan önce danışın. Uygun güvenlik uygulamaları kimyasal reaksiyonlar, bir duman hood ve kişisel koruyucu ekipman kullanımı dahil etmek için kullanırlar. Hızlı Hidrojen gaz evrim yüksek basınç pop için kapaklar neden tepki tüpler ve çözümleri sprey dışarı neden olabilir. Tepki tüp kapakları açık olarak belirtilen iletişim kuralı kalmadığından emin olun.
1. metal jel hazırlık
<ol><li>
Metal iyon çözümleri hazırlanması.
	<ol>
<li>2 mL 0.1 M çözümleri aşağıdaki tuzları, hazırlamak: HAuCl4•3H2O Na ve2PdCl4 deiyonize su. 2 mL 0.1 M K2PtCl6 bir 1:1 (v/v) su hazırlamak ve etanol çözücü. Tuz dağılmasına yardımcı olmak için şiddetle sallamak ve girdap çözümleri.</li>
	</ol>
</li>
	<li>
İndirgeyici çözüm hazırlanması.
	<ol>
<li>10 mL 0.1 M çözümleri aşağıdaki azalan bakiyeli ajanların hazırlamak: dimethylamine borane (DMAB) ve NaBH4 (sodyum borhidrür).</li>
	</ol>
</li>
	<li>
Au hazırlanması jelleri.
	<ol>
<li>0.5 mL 0.1 M HAuCl4•3H2O çözeltisi 1.7 mL veya 2.0 mL microcentrifuge tüp içine pipet. Zorla DMAB 0.5 mL tuz ve indirgeyici çözümleri hızlı bir karışımını sağlamak için altın çözüm ile microcentrifuge tüp içine pipet. Çözümler karışınca microcentrifuge tüp dikey olarak açık tüp kapaklı tüp raf yerleştirin. Not: Eğer tüp kapağı sol kapalı, Hidrojen gaz evrim içinde basınç kapağı açık pop zorlamak ve potansiyel olarak azaltma karışımı sprey için neden olur.</li>
	</ol>
</li>
	<li>
Pd hazırlanması jelleri.
	<ol>
<li>0.5 mL 0.1 M Na2PdCl4 çözeltisi 1.7 mL veya 2.0 mL microcentrifuge tüp içine pipet. Zorla NaBH4 0.5 mL Paladyum çözüm ile microcentrifuge tüp içine pipet. Yer microcentrifuge tüpü bir tüp raf tüp kapaklı dikey olarak açın.</li>
	</ol>
</li>
	<li>
Pt hazırlanması jelleri.
	<ol>
<li>0.5 mL 0.1 M K2PtCl6 çözüm 1.7 mL veya 2.0 mL microcentrifuge tüp içine pipet. Zorla DMAB 0.5 mL platin çözüm ile microcentrifuge tüp içine pipet. Yer microcentrifuge tüpü bir tüp raf tüp kapaklı dikey olarak açın.</li>
	</ol>
</li>
	<li>
Tüp inversiyon.
	<ol>
<li>Yaklaşık 5 dk microcentrifuge tüpleri kap ve için 3 - 5 kez yavaşça tersine çevirin yardım metal parçacıklar metal jel parçası değil birleştirme içinde. Emin olun tüp kapaklar hemen olan kapağını tüpler ters çevirme sonra ve Değiştir tüpleri bir rafa tüp dikey yönünü korumak için.</li>
	</ol>
</li>
	<li>
Denge.<ol>
<li>Otomatik Güncelleştirmeler, Pd ve Pt jelleri başlangıçta birkaç dakika içinde sahipken doğmakta olan jeller indirgeyici çözüm tam metal iyonları azalma ve gerçekleşmesi yüzey serbest enerji minimizasyonu için izin vermek 3-6 h için bırakın. Not: Metal jelleri karma metal iyon ve indirgeyici çözüm ilk hacmi daha küçük bir hacim kaplar. Bazı ek hafif cilt daralma denge dönemde gözlenen daha altın tırnaklar için jeller telaffuz ve25olgunlaşma Ostwald nedeniyle olduğuna inanılan.</li>
	</ol>
</li>
	<li>
Jel durulama.<ol>
<li>Otomatik Güncelleştirmeler, Pd ve Pt jelleri denge dönemi nden sonra için aşırı indirgeyici çözüm kaldırmayı ancak metal jel su altında kalması yeterli çözüm hacim bırakmak. Çözüm menisküs ile temas metal jel gelmez emin olun. Not: her ne kadar jelleri kılcal bir spatula ile çözüm arasında aktarmak için yeterince kararlı metal çözüm menisküs ile temas nedeniyle zorlar deforme ve son aerogel yoğunluk artışı sonuçlanan jelleri sıkıştırmak. Bu bazı indirgeyici çözüm ne zaman transfer deiyonize su batık jel ile tüp kalmasını gerektirir.</li>
		<li>Yavaş yavaş tepki microcentrifuge tüpler tepesine deiyonize su pipet. Bir 50 mL konik tüp deiyonize su dolu microcentrifuge tüpte daldırın ve jel microcentrifuge tüp dışarı slayt sağlar.</li>
		<li>Deiyonize su 24 h için jel bırakın ve 12 h su değiştirin. Jel ile temas gelmek sıvı bir menisküs izin vermemek için yapın.</li>
	</ol>
</li>
</ol>2. ıslak Metal jelleri karakterizasyonu elektrokimyasal yüzey alanı (ECSA)
Not: Elektrokimyasal karakterizasyonu donma kurutma iletken önce ıslak metal jelleri gerçekleştirilir. Elde edilen ECSA sonra son aerogel yapısı ve yüzey bir tahmindir. Azot adsorpsiyon ölçümleri kurutulmuş aerogels yüzey alanı tahmin etmek için kullanılır.
<ol><li>
Solvent Satım.<ol>
<li>Büyük bir kısmını Au deiyonize su kaldırmak için Pd ve Pt çözümler mümkün olduğunca durulama ve sıvı menisküs jel ile temas gelmediğinden emin olun.</li>
		<li>50 mL, 0,5 M KCl jel gözenekleri içinde elektrolit destekleyici deiyonize su alışverişi için konik tüpler için ekleyin. Jelleri KCl çözelti için 24 saat içinde bırakın.</li>
	</ol>
</li>
	<li>
Çalışma elektrodu hazırlanması.
	<ol>
<li>1 mm platin tel elektrot iyi bir fırça veya maruz tel ucu 4-5 mm uzunluğu bırakarak diğer kullanma aygıt kullanma non-reaktif cila ile kat.</li>
		<li>Kuru cila için 20 dakika izin verin.</li>
		<li>En az iki kat vernik uygulayın.</li>
	</ol>
</li>
	<li>
3-Elektrot Hücre set-up.
	<ol>
<li>3-Elektrot Hücre set-up bir Ag/AgCl ile (3 doymuş M) kullanmak referans elektrot, 0,5 mm çap Pt tel yardımcı/sayaç elektrot ve Lake boyalı çalışma elektrot.</li>
		<li>Bir plastik 50 mL konik tüp yarıya ve elektrokimyasal bir şişe kullanın.</li>
		<li>Jel çalışma elektrodu ile iki yöntemden biri ile başvurun: 1) Impaled jel veya 2) iletişim modu.<ol>
<li>
Elektrot - Impaled jel çalışma.<ol>
<li>Alt kısmındaki değiştirilmiş 50 mL konik tüp jel ile hafifçe cila kaplanmış elektrot jel yerleştirin. Not: Pd ve Pt elektrot ekleme daha sık üzerine kırık jelleri ise Impaled jel yöntemi Au jelleri ile daha etkili olmaktadır.</li>
			</ol>
</li>
			<li>
Çalışma elektrot - modu başvurun.<ol>
<li>Konik Boru iç yüzeyi boyunca Lake kaplamalı çalışma elektrot yerleştirin ve metal jel maruz Pt tel çalışma elektrot üstünde bekletin.</li>
			</ol>
</li>
		</ol>
</li>
	</ol>
</li>
	<li>
Elektrokimyasal empedans spektroskopisi (EIS).<ol>
<li>EIS frekansları 100 MHz ve 1 10 mV genlik sinüs dalga kullanarak mHz arasında inceden inceye gözden geçirmek potentiostatic gerçekleştirin. Geçerli taşmaları durumunda galvanostatic EIS aynı frekans aralığı ve 100-200 mA genlik sinüs dalga ile kullanın.</li>
	</ol>
</li>
	<li>
EIS verilerden elektrokimyasal yüzey alanı (ECSA) belirlenmesi.<ol>
<li>İçin Z ", empedans, en düşük fiyat EIS frekans f 1 mHz ve örnek kitle tarafından m, bölen sanal bileşeni belirli kapasitans, Cspbelirlemek için aşağıdaki denklemi kullanabilir: C SP = 1 / (2πfZ "m) (1) Not: Tüm çözümde metal iyonlarının jel oluşturmak için azaltılır varsayarak tarafından verilen bu ECSA adım 3'te aşağıdaki kurutma dondurmak için bir ıslak jel önceden belirlenir, kitle belirleyin. Bu duymadığını, herhangi bir gerçek verim az %100 Cspküçümseyen neden olur.</li>
	</ol>
</li>
	<li>
Çevrimsel voltammetry (CV).<ol>
<li>Tarama gore 100, 75, 50, 25, 10, 5 ve 1 mV/s CV ölçümleri için kullanın. Voltaj aralığı için 0,2 V-0.2 (vs Ag/AgCl) Au tırnaklar için jeller kullanın ve 0,1 için 0,4 V Pd ve Pt jelleri hidrojen adsorpsiyon ve desorpsiyon ve korunmada gereken indirgeme potansiyelini metal önlemek için seçin.</li>
	</ol>
</li>
	<li>
Elektrokimyasal yüzey alanı (ECSA) CV verilerden belirlenmesi.<ol>
<li>En yavaş CV tarama hızı 1 mV/s kullanın ve özel kapasite ile denklemi hesaplamak: C SP = (∫ivdv) / (2μmΔV) (2) Not: Burada ben ve v akım ve CV tarama (A ve V) potansiyel vardır, tarama oranıdır μ (V/s), jel kütlesi m (g) ise ΔV deşarj (vs Ag/AgCl) potansiyel pencere.</li>
	</ol>
</li>
</ol>3. Aerogel hazırlanması ve karakterizasyonu.
<ol><li>Adım 1.8 otomatik güncelleştirmeler, Pd ve Pt jelleri deiyonize suyla durulama su kaldırmak ve su menisküs metal jellerin ile temas halinde gelir değil emin olun.</li>
	<li>En az 30 dk Transfer için bir donma kurutma makinesi 4 set noktası basınçla donmuş metal jelleri-80 ° C dondurucuya jelleri yer Pa veya daha düşük.</li>
</ol>

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Computations from Nitrogen Isotherms.</a> Journal of the American Chemical Society. 73, 373-380 (1951).</li><li>Brunauer, B., Emmett, P., Teller, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adsorption+of+Gases+in+Multimolecular+Layers.">Adsorption of Gases in Multimolecular Layers.</a> Journal of the American Chemical Society. 60, 309-319 (1938).</li><li>Herrmann, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multimetallic+Aerogels+by+Template-Free+Self-Assembly+of+Au,+Ag,+Pt,+and+Pd+Nanoparticles.">Multimetallic Aerogels by Template-Free Self-Assembly of Au, Ag, Pt, and Pd Nanoparticles.</a> Chemistry of Materials. 26, 1074-1083 (2014).</li><li>Kornyshev, A., Irbakh, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Double-layer+capacitance+on+a+rough+metal+surface.">Double-layer capacitance on a rough metal surface.</a> Physical Review E. 53, 6192-6199 (1996).</li><li>Bisquert, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Influence+of+the+boundaries+in+the+impedance+of+porous+film+electrodes.">Influence of the boundaries in the impedance of porous film electrodes.</a> Physical Chemistry Chemical Physics. 2, 4185-4192 (2000).</li><li>Bisquert, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Theory+of+the+Impedance+of+Electron+Diffusion+and+Recombination+in+a+Thin+Layer.">Theory of the Impedance of Electron Diffusion and Recombination in a Thin Layer.</a> Journal of Physical Chemistry B. 106, 325-333 (2002).</li><li>Lu, K., Yuan, L., Xin, X., Xu, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hybridization+of+graphene+oxide+with+commercial+graphene+for+constructing+3D+metal-free+aerogel+with+enhanced+photocatalysis.">Hybridization of graphene oxide with commercial graphene for constructing 3D metal-free aerogel with enhanced photocatalysis.</a> Applied Catalysis B. 226, 16-22 (2018).</li><li>Nystron, G., Roder, L., Fernandez-Ronco, M., Mezzenga, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Amyloid+Templated+Organic+Inorganic+Hybrid+Aerogels.">Amyloid Templated Organic Inorganic Hybrid Aerogels.</a> Advanced Functional Materials. , 1703609-1703620 (2017).</li></ol>

Yazarlar ifşa gerek yok.

Noble metal aerogel sentez yöntemi sonuçları daha yavaş sentez teknikleri için karşılaştırılabilir gözenekli, yüksek yüzey alanı yekpare hızlı oluşumunda burada sundu. İndirgeyici çözüm oranı 1:1 (v/v) metal iyon eriyik önerilen jel oluşumu modeli kolaylaştırmak önemlidir. Hızlı Hidrojen gaz evrim metal iyonları elektrokimyasal azalma bir yan ürün olarak ikincil bir indirgeyici hizmet vermektedir ve yoğunlaştırılması ve nano tanecikleri jel oluşumu sırasında büyüyen füzyon birli...

Enerji depolama ve dönüşüm, kataliz ve sensör uygulamaları geniş bir yarar--dan kimyasal reaktivite ve toplu taşıma özellikleri1,2üzerinde kontrol sağlayan üç boyutlu metalik nanoyapıların 3,4,5. Böyle daha fazla 3 boyutlu metalik nanoyapıların iletkenlik, süneklik, yumuşaklık ve gücü8,9geliştirmek. Entegrasyon cihazların içine malzeme müstakil veya destek malzemeleri ile birlikte olmasını gerektirir. Nanomalzemeler destek yapıları üzerine birleşme etkin malzeme en aza indirmek için bir yol sağlar, ancak zayıf adsorpsiyon ve aygıt işlemi10,11sırasında nihai Aglomerasyon muzdarip olabilir.
Bireysel nanopartikül boyutunu ve şeklini denetlemek için sentez yöntemleri çeşitli olmakla birlikte, birkaç yaklaşımlar bitişik 3 boyutlu Nanomalzemeler12,13,14üzerinde denetim sağlar. Noble metal 3 boyutlu nanoyapıların monodisperse nano tanecikleri, sol-jel oluşumu, nanopartikül birleştirme, kompozit malzemeler, nanosphere zincirler ve biotemplating15,16 dithiol bağlantı oluşturulmuştur , 17 , 18. çoğu bu yaklaşımlar, sentez kez gün ile istenen malzeme vermeye hafta sırasına gerektirir. Noble metal nanofoams habercisi tuz çözümleri doğrudan azalma sentezlenmiş mikrometre uzunluğunda yüzlerce kısa menzilli sırasını ve daha hızlı bir sentez zaman ölçeği ile hazırlanan, ancak aygıt tümleştirmesi için tuşuna basarak mekanik gerektirir 19 , 20.
İlk Kistler tarafından rapor, aerogels gözenekli yapıları ile büyüklük onların toplu malzeme karşıtları21,22,23 daha az yoğun olan yüksek belirli yüzey alanları elde etmek için bir sentez yol sağlamak . 3 boyutlu yapılara makroskopik uzunluk ölçek toplu malzemelerin uzanan nanopartikül toplamları veya destek malzemeleri veya mekanik işleme gerektiren nanofoams üzerinde bir avantaj sunuyor. Aerogels porozite ve parçacık özellik boyutu, ancak, kontrol etmek için bir sentez yol sentez zaman, sunarken ve bazı ajanlar veya bağlayıcı molekülleri, artar genel işlem adımları ve zaman sınırı kullanımını durumda.
Burada altın, paladyum, platin aerogels üzerinden bir hızlı, doğrudan çözüm tabanlı azaltma sentezlemek için bir yöntem24sunulmuştur. Azalan bakiyeli ajanlar bir 1:1 ile çeşitli öncü noble metal iyonları birleştirerek (v/v) oranı sonuçları saniye dakika içinde metal jelleri oluşumunda çok uzun sol-jel gibi diğer teknikleri sentezi süreleri karşılaştırıldığında. Microcentrifuge tüp veya küçük hacimli konik tüp kullanımı güçlü Hidrojen gaz evrim kolaylaştıran bir önerilen çekirdekleşme, büyüme, yoğunlaştırılması, Füzyon, jel oluşumu için denge modeli azaltma adım bir yan ürün olarak yararlanır. Aerogel nanostructure özelliği boyutlarda yakın bir ilişki elektron mikroskobu görüntü analizi, x-ışını diffractometry, azot gazı adsorpsiyon, elektrokimyasal empedans spektroskopisi ve çevrimsel voltammetry tarama ayarlarıyla belirlenir. Solvent erişilebilir belirli yüzey alanı elektrokimyasal empedans spektroskopisi ve çevrimsel voltammetry ile belirlenir. Bu sentez yöntemi noble metal aerogels için yüksek o belirli yüzey alanı yekpare bir hızlı ve doğrudan azaltma yaklaşımla elde gösterir.

<table><tbody><tr><td>HAuCl&lt;sub&gt;4&lt;/sub&gt;&amp;Yuml;&amp;bull;3H&lt;sub&gt;2&lt;/sub&gt;O&amp;nbsp;</td><td>Sigma-Aldrich</td><td>16961-25-4</td><td></td></tr><tr><td>Na&lt;sub&gt;2&lt;/sub&gt;PdCl&lt;sub&gt;4&lt;/sub&gt;</td><td>Sigma-Aldrich</td><td>13820-40-1</td><td></td></tr><tr><td>K&lt;sub&gt;2&lt;/sub&gt;PtCl&lt;sub&gt;6&lt;/sub&gt;</td><td>Sigma-Aldrich</td><td>16921-30-5</td><td></td></tr><tr><td>Pd(NH&lt;sub&gt;3&lt;/sub&gt;)&lt;sub&gt;4&lt;/sub&gt;Cl&lt;sub&gt;2&lt;/sub&gt;</td><td>Sigma-Aldrich</td><td>13933-31-8</td><td></td></tr><tr><td>K&lt;sub&gt;2&lt;/sub&gt;PtCl&lt;sub&gt;4&lt;/sub&gt;</td><td>Sigma-Aldrich</td><td>10025-99-7</td><td></td></tr><tr><td>Pt(NH&lt;sub&gt;3&lt;/sub&gt;)&lt;sub&gt;4&lt;/sub&gt;Cl&lt;sub&gt;2&lt;/sub&gt;&amp;Yuml;&amp;bull;H&lt;sub&gt;2&lt;/sub&gt;O</td><td>Sigma-Aldrich</td><td>13933-31-8</td><td></td></tr><tr><td>dimethylamine borane (DMAB)</td><td>Sigma-Aldrich</td><td>74-94-2</td><td></td></tr><tr><td>NaBH&lt;sub&gt;4&lt;/sub&gt;</td><td>Sigma-Aldrich</td><td>16940-66-2</td><td></td></tr><tr><td>NaH&lt;sub&gt;2&lt;/sub&gt;PO&lt;sub&gt;2&lt;/sub&gt;&amp;Yuml;&amp;bull;H&lt;sub&gt;2&lt;/sub&gt;O</td><td>Sigma-Aldrich</td><td>10039-56-2</td><td></td></tr><tr><td>Ethanol</td><td>Sigma-Aldrich</td><td>792780</td><td></td></tr><tr><td>Snap Cap Microcentrifuge Tubes, 2.0 mL</td><td>Cole Parmer</td><td>UX-06333-70</td><td></td></tr><tr><td>Snap Cap Microcentrifuge Tubes, 1.7 mL</td><td>Cole Parmer</td><td>UX-06333-60</td><td></td></tr><tr><td>Conical Centrifuge Tubes 15mL</td><td>Stellar Scientific</td><td>T15-101&amp;nbsp;</td><td></td></tr><tr><td>Ag/AgCl Reference Electrode</td><td>BASi</td><td>MF-2052</td><td></td></tr><tr><td>Pt wire electrode</td><td>BASi</td><td>MF-4130</td><td></td></tr><tr><td>Miccrostop Lacquer</td><td>Tober Chemical Division</td><td>NA</td><td></td></tr><tr><td>Potentiostat</td><td>Biologic-USA</td><td>VMP-3</td><td>Electrochemical analysis-EIS, CV</td></tr><tr><td>Freeze Dryer</td><td>Labconco</td><td>Freezone 2.5 Liter</td><td>Aerogel freeze drying</td></tr><tr><td>XRD</td><td>PanAlytical</td><td>Empyrean</td><td>X-ray diffractometry</td></tr><tr><td>Surface and Pore Analyzer</td><td>Quantachrome</td><td>NOVA 4000e</td><td>Nitrogen gas adsorption</td></tr><tr><td>ImageJ, Image analysis software</td><td>National Institute of Health</td><td>NA</td><td>SEM image analysis</td></tr></tbody></table>

a rapid synthesis method for au, pd, and pt aerogels via direct solution-based reduction

Burada, altın, paladyum, platin aerogels üzerinden bir hızlı, doğrudan çözüm tabanlı azaltma sentezlemek için bir yöntem sunulur. Çeşitli öncü noble metal iyonları saniye dakika içinde metal jelleri oluşumunda bir 1:1 (v/v) oranı sonuçlarında azalan bakiyeli ajanlar ile kombinasyonu çok uzun sol-jel gibi diğer teknikleri sentezi süreleri karşılaştırıldığında. Bir microcentrifuge azaltma adımda iletken tüp ya da küçük hacimli konik tüp kolaylaştırır bir önerilen çekirdekleşme, büyüme, yoğunlaştırılması, Füzyon, denge modeli ile son jel geometri ilk tepki ses daha küçük jel oluşumu için. Bu yöntem, güçlü Hidrojen gaz evrim azaltma adım ve reaktif konsantrasyonları bir sonucu olarak bir yan ürün olarak yararlanır. Solvent erişilebilir belirli yüzey alanı elektrokimyasal empedans spektroskopisi ve çevrimsel voltammetry ile belirlenir. Sonra durulama ve kurutma donma, elektron mikroskobu, x-ışını diffractometry ve azot gazı adsorpsiyon tarama ile elde edilen aerogel yapısı incelenir. Sentez yöntemi ve karakterizasyonu teknikleri aerogel bağ boyutları bir yakın yazışmalarda neden. Bu sentez yöntemi noble metal aerogels için yüksek o belirli yüzey alanı yekpare bir hızlı ve doğrudan azaltma yaklaşımla elde gösterir.

Metal iyon ve indirgeyici çözümleri birlikte sonuçları hemen dinç gaz evrim ile koyu siyah renk dönüm çözümlerinde eklenmesi. Şekil 1' de gösterilen önerilen jel oluşumu mekanizması gözlem reaksiyon ilerleme göstermektedir. Jel oluşumu 1) nanopartikül çekirdekleşme, 2) büyüme, 3) yoğunlaştırılması, 4) füzyon ve 5) denge beş adımları boyunca devam eder. İlk dört adımları ilk birkaç dakika boyunca 3-6 jel indirgeyici çöz?...

Watch this Scientific Journal Video about A Rapid Synthesis Method for Au, Pd, and Pt Aerogels Via Direct Solution-Based Reduction at JoVE.com

A Rapid Synthesis Method for Au, Pd, and Pt Aerogels Via Direct Solution-Based Reduction

Otomatik Güncelleştirmeler, Pd ve Pt Aerogels üzerinden doğrudan çözüm tabanlı azaltma için hızlı sentez yöntemi

Otomatik Güncelleştirmeler, Pd ve Pt aerogels elde etmek için hızlı, doğrudan çözüm tabanlı azaltma sentez yöntemi gösterilir.

Here, a method to synthesize gold, palladium, and platinum aerogels via a rapid, direct solution-based reduction is presented. The combination of various ...

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8.6K Görüntüleme.  United States Military Academy, West Point. Otomatik Güncelleştirmeler, Pd ve Pt aerogels elde etmek için hızlı, doğrudan çözüm tabanlı azaltma sentez yöntemi gösterilir.

Video: A Rapid Synthesis Method for Au, Pd, and Pt Aerogels Via Direct Solution-Based Reduction

Preparing Silica Aerogel Monoliths via a Rapid Supercritical Extraction Method

A procedure for the fabrication of monolithic silica aerogels in eight hours or less via a rapid supercritical extraction process is described. The procedure requires 15-20 min of preparation time, during which a liquid precursor mixture is prepared and poured into wells of a metal mold that is placed between the platens of a hydraulic hot press, followed by several hours of processing within the hot press. The precursor solution consists of a 1.0:12.0:3.6:3.5 x 10-3 molar ratio of tetramethylorthosilicate (TMOS):methanol:water:ammonia. In each well of the mold, a porous silica sol-gel matrix forms. As the temperature of the mold and its contents is increased, the pressure within the mold rises. After the temperature/pressure conditions surpass the supercritical point for the solvent within the pores of the matrix (in this case, a methanol/water mixture), the supercritical fluid is released, and monolithic aerogel remains within the wells of the mold. With the mold used in this procedure, cylindrical monoliths of 2.2 cm diameter and 1.9 cm height are produced. Aerogels formed by this rapid method have comparable properties (low bulk and skeletal density, high surface area, mesoporous morphology) to those prepared by other methods that involve either additional reaction steps or solvent extractions (lengthier processes that generate more chemical waste).The rapid supercritical extraction method can also be applied to the fabrication of aerogels based on other precursor recipes.

This article describes a rapid supercritical extraction method for fabricating silica aerogels. By utilizing a confined mold and hydraulic hot press, monolithic aerogels can be made in eight hours or less.

Bir Rapid Süperkritik Ekstraksiyon Yöntemi ile Silika AEROJEL Monoliths hazırlanıyor

A procedure for the fabrication of monolithic silica aerogels in eight hours or less via a rapid supercritical extraction process is described. The ...

Kimya

Synthesis and Testing of Supported Pt-Cu Solid Solution Nanoparticle Catalysts for Propane Dehydrogenation

A convenient method for the synthesis of bimetallic Pt-Cu catalysts and performance tests for propane dehydrogenation and characterization are demonstrated here. The catalyst forms a substitutional solid solution structure, with a small and uniform particle size around 2 nm. This is realized by careful control over the impregnation, calcination, and reduction steps during catalyst preparation and is identified by advanced in situ synchrotron techniques. The catalyst propane dehydrogenation performance continuously improves with increasing Cu:Pt atomic ratio.

A convenient method for the synthesis of 2 nm supported bimetallic nanoparticle Pt-Cu catalysts for propane dehydrogenation is reported here. In situ synchrotron X-ray techniques allow for the determination of the catalyst structure, which is typically unobtainable using laboratory instruments.

Propan Dehidrojenasyon için Desteklenen Pt-Cu Katı Solüsyon Nanopartikül Katalizörlerinin Sentezi ve Testi

A convenient method for the synthesis of bimetallic Pt-Cu catalysts and performance tests for propane dehydrogenation and characterization are ...

Fabrication and Testing of Catalytic Aerogels Prepared Via Rapid Supercritical Extraction

Protocols for preparing and testing catalytic aerogels by incorporating metal species into silica and alumina aerogel platforms are presented. Three preparation methods are described: (a) the incorporation of metal salts into silica or alumina wet gels using an impregnation method; (b) the incorporation of metal salts into alumina wet gels using a co-precursor method; and (c) the addition of metal nanoparticles directly into a silica aerogel precursor mixture. The methods utilize a hydraulic hot press, which allows for rapid (&#60;6 h) supercritical extraction and results in aerogels of low density (0.10 g/mL) and high surface area (200-800 m2/g). While the work presented here focuses on the use of copper salts and copper nanoparticles, the approach can be implemented using other metal salts and nanoparticles. A protocol for testing the three-way catalytic ability of these aerogels for automotive pollution mitigation is also presented. This technique uses custom-built equipment, the Union Catalytic Testbed (UCAT), in which a simulated exhaust mixture is passed over an aerogel sample at a controlled temperature and flow rate. The system is capable of measuring the ability of the catalytic aerogels, under both oxidizing and reducing conditions, to convert CO, NO and unburned hydrocarbons (HCs) to less harmful species (CO2, H2O and N2). Example catalytic results are presented for the aerogels described.

Here we present protocols for preparing and testing catalytic aerogels by incorporating metal species into silica and alumina aerogel platforms. Methods for preparing materials using copper salts and copper-containing nanoparticles are featured. Catalytic testing protocols demonstrate the effectiveness of these aerogels for three-way catalysis applications.

İmalat ve katalitik Aerogels hızlı süperkritik ayıklama hazırlanan test

Protocols for preparing and testing catalytic aerogels by incorporating metal species into silica and alumina aerogel platforms are presented. Three ...

A Continuous-flow Photocatalytic Reactor for the Precisely Controlled Deposition of Metallic Nanoparticles

In this work, a novel photocatalytic reactor for the pulsed and controlled excitation of the photocatalyst and the precise deposition of metallic nanoparticles is developed. Guidelines for the replication of the reactor and its operation are provided in detail. Three different composite systems (Pt/graphene, Pt/TiO2, and Au/TiO2) with monodisperse and uniformly distributed particles are produced by this reactor, and the photodeposition mechanism, as well as the synthesis optimization strategy, are discussed. The synthesis methods and their technical aspects are described comprehensively. The role of the ultraviolet (UV) dose (in each excitation pulse) on the photodeposition process is investigated and the optimum values for each composite system are provided.

For a continuous and scalable synthesis of noble-metal-based nanocomposites, a novel photocatalytic reactor is developed and its structure, operation principles, and product quality optimization strategies are described.

Metalik nano tanecikleri tam kontrollü birikimi için sürekli akış Fotokatalitik reaktör

In this work, a novel photocatalytic reactor for the pulsed and controlled excitation of the photocatalyst and the precise deposition of metallic ...

Synthesis Method for Cellulose Nanofiber Biotemplated Palladium Composite Aerogels

Here, a method to synthesize cellulose nanofiber biotemplated palladium composite aerogels is presented. Noble metal aerogel synthesis methods often result in fragile aerogels with poor shape control. The use of carboxymethylated cellulose nanofibers (CNFs) to form a covalently bonded hydrogel allows for the reduction of metal ions such as palladium on the CNFs with control over both nanostructure and macroscopic aerogel monolith shape after supercritical drying. Crosslinking the carboxymethylated cellulose nanofibers is achieved using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) in the presence of ethylenediamine. The CNF hydrogels maintain their shape throughout synthesis steps including covalent crosslinking, equilibration with precursor ions, metal reduction with high concentration reducing agent, rinsing in water, ethanol solvent exchange, and CO2 supercritical drying. Varying the precursor palladium ion concentration allows for control over the metal content in the final aerogel composite through a direct ion chemical reduction rather than relying on the relatively slow coalescence of pre-formed nanoparticles used in other sol-gel techniques. With diffusion as the basis to introduce and remove chemical species into and out of the hydrogel, this method is suitable for smaller bulk geometries and thin films. Characterization of the cellulose nanofiber-palladium composite aerogels with scanning electron microscopy, X-ray diffractometry, thermal gravimetric analysis, nitrogen gas adsorption, electrochemical impedance spectroscopy, and cyclic voltammetry indicates a high surface area, metallized palladium porous structure.

A synthesis method for cellulose nanofiber biotemplated palladium composite aerogels is presented.The resulting composite aerogel materials offer potential for catalysis, sensing, and hydrogen gas storage applications.

Selüloz nanofiber Biotemkaplama Palladium kompozit Aerogels için sentez yöntemi

Here, a method to synthesize cellulose nanofiber biotemplated palladium composite aerogels is presented. Noble metal aerogel synthesis methods often ...

Photodeposition of Pd onto Colloidal Au Nanorods by Surface Plasmon Excitation

A protocol is described to photocatalytically guide Pd deposition onto Au nanorods (AuNR) using surface plasmon resonance (SPR). Excited plasmonic hot electrons upon SPR irradiation drive reductive deposition of Pd on colloidal AuNR in the presence of [PdCl4]2-. Plasmon-driven reduction of secondary metals potentiates covalent, sub-wavelength deposition at targeted locations coinciding with electric field &#8220;hot-spots&#8221; of the plasmonic substrate using an external field (e.g., laser). The process described herein details a solution-phase deposition of a catalytically-active noble metal (Pd) from a transition metal halide salt (H2PdCl4) onto aqueously-suspended, anisotropic plasmonic structures (AuNR). The solution-phase process is amenable to making other bimetallic architectures. Transmission UV-vis monitoring of the photochemical reaction, coupled with ex situ XPS and statistical TEM analysis, provide immediate experimental feedback to evaluate properties of the bimetallic structures as they evolve during the photocatalytic reaction. Resonant plasmon irradiation of AuNR in the presence of [PdCl4]2- creates a thin, covalently-bound Pd0 shell without any significant dampening effect on its plasmonic behavior in this representative experiment/batch. Overall, plasmonic photodeposition offers an alternative route for high-volume, economical synthesis of optoelectronic materials with sub-5 nm features (e.g., heterometallic photocatalysts or optoelectronic interconnects).

A protocol for anisotropic photodeposition of Pd onto aqueously-suspended Au nanorods via localized surface plasmon excitation is presented.

Yüzey Plazmon Uyarma tarafından Kolloidal Au Nanorods üzerine Pd Photodeposition

A protocol is described to photocatalytically guide Pd deposition onto Au nanorods (AuNR) using surface plasmon resonance (SPR). Excited plasmonic hot ...

A Salt-Templated Synthesis Method for Porous Platinum-based Macrobeams and Macrotubes

The synthesis of high surface area porous noble metal nanomaterials generally relies on time consuming coalescence of pre-formed nanoparticles, followed by rinsing and supercritical drying steps, often resulting in mechanically fragile materials. Here, a method to synthesize nanostructured porous platinum-based macrotubes and macrobeams with a square cross section from insoluble salt needle templates is presented. The combination of oppositely charged platinum, palladium, and copper square planar ions results in the rapid formation of insoluble salt needles. Depending on the stoichiometric ratio of metal ions present in the salt-template and the choice of chemical reducing agent, either macrotubes or macrobeams form with a porous nanostructure comprised of either fused nanoparticles or nanofibrils. Elemental composition of the macrotubes and macrobeams, determined with x-ray diffractometry and x-ray photoelectron spectroscopy, is controlled by the stoichiometric ratio of metal ions present in the salt-template. Macrotubes and macrobeams may be pressed into free standing films, and the electrochemically active surface area is determined with electrochemical impedance spectroscopy and cyclic voltammetry. This synthesis method demonstrates a simple, relatively fast approach to achieve high-surface area platinum-based macrotubes and macrobeams with tunable nanostructure and elemental composition that may be pressed into free-standing films with no required binding materials.

A synthesis method to obtain porous platinum-based macrotubes and macrobeams with a square cross section through chemical reduction of insoluble salt-needle templates is presented.

Gözenekli Platin Bazlı Makrobeamler ve Makrotüpler için Tuz Şablonlu Sentez Yöntemi

The synthesis of high surface area porous noble metal nanomaterials generally relies on time consuming coalescence of pre-formed nanoparticles, followed ...

Preparation of Silver-Palladium Alloyed Nanoparticles for Plasmonic Catalysis under Visible-Light Illumination

Localized surface plasmon resonance (LSPR) in plasmonic nanoparticles (NPs) can accelerate and control the selectivity of a variety of molecular transformations. This opens possibilities for the use of visible or near-IR light as a sustainable input to drive and control reactions when plasmonic nanoparticles supporting LSPR excitation in these ranges are employed as catalysts. Unfortunately, this is not the case for several catalytic metals such as palladium (Pd). One strategy to overcome this limitation is to employ bimetallic NPs containing plasmonic and catalytic metals. In this case, the LSPR excitation in the plasmonic metal can contribute to accelerate and control transformations driven by the catalytic component. The method reported herein focuses on the synthesis of bimetallic silver-palladium (Ag-Pd) NPs supported on ZrO2 (Ag-Pd/ZrO2) that acts as a plasmonic-catalytic system. The NPs were prepared by co-impregnation of corresponding metal precursors on the ZrO2 support followed by simultaneous reduction leading to the formation of bimetallic NPs directly on the ZrO2 support. The Ag-Pd/ZrO2 NPs were then used as plasmonic catalysts for the reduction of nitrobenzene under 425 nm illumination by LED lamps. Using gas chromatography (GC), the conversion and selectivity of the reduction reaction under the dark and light irradiation conditions can be monitored, demonstrating the enhanced catalytic performance and control over selectivity under LSPR excitation after alloying non-plasmonic Pd with plasmonic metal Ag. This technique can be adapted to a wide range of molecular transformations and NPs compositions, making it useful for the characterization of the plasmonic catalytic activity of different types of catalysis in terms of conversion and selectivity.

Presented here is a protocol for the synthesis of silver-palladium (Ag-Pd) alloy nanoparticles (NPs) supported on ZrO2 (Ag-Pd/ZrO2). This system allows for harvesting energy from visible light irradiation to accelerate and control molecular transformations. This is illustrated by nitrobenzene reduction under light irradiation catalyzed by Ag-Pd/ZrO2 NPs.

Görünür-Işık Aydınlatması Altında Plazmonik Kataliz için Gümüş-Paladyum Alaşımlı Nanopartiküllerin Hazırlanması

Localized surface plasmon resonance (LSPR) in plasmonic nanoparticles (NPs) can accelerate and control the selectivity of a variety of molecular ...

Aesthetically Enhanced Silica Aerogel Via Incorporation of Laser Etching and Dyes

A procedure for aesthetically enhancing silica aerogel monoliths by laser etching and incorporation of dyes is described in this manuscript. Using a rapid supercritical extraction method, large silica aerogel monolith (10 cm x 11 cm x 1.5 cm) can be fabricated in about 10 h. Dyes incorporated into the precursor mixture result in yellow-, pink- and orange-tinged aerogels. Text, patterns, and images can be etched onto the surface (or surfaces) of the aerogel monolith without damaging the bulk structure. The laser engraver can be used to cut shapes from the aerogel and form colorful mosaics.

This protocol describes a method for etching text, patterns, and images onto the surface of silica aerogel monoliths in native and dyed form and assembling the aerogels into mosaic designs.

Lazer Gravür ve Boyaların Dahili Yoluyla Estetik Olarak Geliştirilmiş Silika Aerogel

A procedure for aesthetically enhancing silica aerogel monoliths by laser etching and incorporation of dyes is described in this manuscript. Using a rapid ...

Mühendislik

Catalytic Reactions at Amine-Stabilized and Ligand-Free Platinum Nanoparticles Supported on Titania During Hydrogenation of Alkenes and Aldehydes

Ligands like amines are used in the colloidal synthesis approach to protect platinum nanoparticles (Pt NP&#39;s) from agglomeration. Normally, ligands like amines are removed by diverse pre-treatment procedures before use in heterogeneous catalysis as amines are considered as a catalyst poison. However, a possible beneficial influence of these surface modifiers on hydrogenation reactions, which is known from spectator species on metal surfaces, is often neglected.
Therefore, amine-stabilized Pt nanoparticles supported by titania (P25) were used without any pre-treatment in order to elucidate a possible influence of the ligand in liquid phase hydrogenation reactions. The catalytic activity of amine-stabilized Pt nanoparticles of two different sizes was investigated in a double-walled stirring tank reactor at 69 &#176;C to 130 &#176;C and 1 atm hydrogen pressure. The conversion of cyclohexene to cyclohexane was determined by gas chromatography (GC) and was compared to ligand-free Pt particles. All catalysts were checked before and after reaction by transmission electron spectroscopy (TEM) and X-ray photoelectron spectroscopy (XPS) for possible changes in size, shape, and ligand shell. The hydrogenation of cyclohexene in liquid phase revealed a higher conversion for amine-stabilized Pt nanoparticles on titania than the ligand-free particles. The hydrogenation of 5-methylfurfural (5-MF) was chosen for a further test reaction, since the hydrogenation of &#945;, &#946;-unsaturated aldehydes is more complex and exhibits various reaction paths. However, XPS and infrared spectroscopy (IR) proved that 5-MF acts as catalyst poison at the given reaction conditions.

This protocol shows a convenient method for comparing the catalytic properties of supported platinum catalysts, synthesized by deposition of nanosized colloids or by impregnation. The hydrogenation of cyclohexene serves as a model reaction to determine the catalytic activity of the catalysts.

Alkenlerin ve Aldehitlerin Hidrojenasyonu Sırasında Titania'da Desteklenen Amin Stabilize ve Ligandsız Platin Nanopartiküllerinde Katalitik Reaksiyonlar

Ligands like amines are used in the colloidal synthesis approach to protect platinum nanoparticles (Pt NP&#39;s) from agglomeration. Normally, ligands ...