Name: a rapid synthesis method for au, pd, and pt aerogels via direct solution-based reduction
Uploaded: 2018-06-18T15:00:00.000+00:00
Duration: 10 min 37 s
Description: Watch this Scientific Journal Video about A Rapid Synthesis Method for Au, Pd, and Pt Aerogels Via Direct Solution-Based Reduction at JoVE.com

著者らは、彼のインスピレーションと技術的な洞察力のためのエアロジェル テクノロジーでスティーブン ・ シュタイナーと陸軍研究所センサーと電子デバイス本部兵器研究で博士クリストファー ・ ヘインズでデリン チュ博士に感謝開発技術センター、米国陸軍 RDECOM ARDEC、・彼らの支援のため米国陸軍ベネット研究所で博士スティーブン ・ Bartolucci。この作品が支持されたアメリカ合衆国陸軍士官学校ウェスト ポイントから部開発研究基金助成金によって。

注意: 使用する前にすべての関連する安全性データ シート (SDS) を参照してください。ヒューム フードや個人用保護具の使用を含むように適切な安全対策の化学反応を実行するときを使用します。急速な水素ガス発生では、高圧をポップにキャップを引き起こす反応管とをスプレーするソリューションに可能性があります。反応チューブ キャップままオープン プロトコルで指定されていることを確認します。
1. 金属のゲルの準備
<ol><li>
金属イオン溶液の調製。
	<ol>
<li>0.1 M 以下の塩溶液 2 mL を準備: HAuCl4•3H2O および Na2PdCl4の脱イオン水。準備 2 mL 0.1 M K21:1 (v/v) 白金6の水とエタノール溶剤。塩の溶解の援助を積極的に振ると渦ソリューション。</li>
	</ol>
</li>
	<li>
還元剤の溶液の調製。
	<ol>
<li>0.1 M 以下の還元剤溶液の 10 mL を準備: ジメチルアミンボラン (と) と NaBH4 (水素化ホウ素ナトリウム)。</li>
	</ol>
</li>
	<li>
ゲルの Au の準備。
	<ol>
<li>1.7 mL、2.0 mL 遠心チューブに 0.1 M HAuCl4•3H2O 溶液 0.5 mL をピペットします。力をこめてピペット 0.5 mL と塩と還元剤溶液の急速なミックスを確保するため金の溶液を遠心管に。ソリューションを混ぜ、一度チューブ キャップとチューブのラックに垂直方向に遠心チューブの場所を開きます。 注: 場合は、チューブのキャップを左を閉じると、水素ガスの発生は強制的に開くにキャップと潜在的削減混合物をスプレー内の圧力を引き起こします。</li>
	</ol>
</li>
	<li>
ゲルの Pd の準備。
	<ol>
<li>1.7 mL、2.0 mL 遠心チューブに 0.1 M Na2PdCl4溶液 0.5 mL をピペットします。パラジウム溶液で遠心管にピペット NaBH4の 0.5 mL の強制的。チューブ キャップとチューブのラックに垂直方向に遠心チューブの場所を開きます。</li>
	</ol>
</li>
	<li>
ゲルの Pt の準備。
	<ol>
<li>1.7 mL、2.0 mL 遠心チューブに 0.1 M K2白金6ソリューションの 0.5 mL のピペットします。強制的とプラチナのソリューションと遠心チューブに 0.5 mL のピペットします。チューブ キャップとチューブのラックに垂直方向に遠心チューブの場所を開きます。</li>
	</ol>
</li>
	<li>
管反転。
	<ol>
<li>約 5 分でマイクロ遠心チューブ用キャップし、軽く逆転して 3-5 回金属のゲルの一部ではなく金属粒子の合体を支援します。確保するチューブを反転後脱帽チューブ キャップがすぐにされ、置換チューブ チューブの垂直方向を維持するためにラックに。</li>
	</ol>
</li>
	<li>
平衡。<ol>
<li>Au, Pd, Pt のゲルは最初数分フォーム、完全に金属イオンの還元と発生する表面自由エネルギー最小化を許可する 3-6 h 還元剤溶液初期ゲルを残します。 注: 金属のゲル混合金属イオン、還元剤の溶液の体積よりも小さいボリュームを占めます。いくつかの追加のわずかな体積収縮平衡時間の間に観察される可能性がありますより金のゲルの発音し、25のオストワルド成長が原因であると考えられています。</li>
	</ol>
</li>
	<li>
ゲルの洗浄をします。<ol>
<li>平衡期間後 Au, Pd, Pt ジェル、過剰の還元剤のソリューションを削除が、金属のゲルのまま湛水解決の十分な容積を残します。ソリューションの半月板は、金属のゲルを接触しないを確認します。 注: ソリューション半月板との接触による強制的にゲルがへらで、キャピラリー ソリューション間の転送に十分な安定している金属が変形が、最終的なエアロゲル密度の増加の結果ゲルを圧縮します。これは、いくつかの還元剤の溶液がゲルを脱イオン水を転送するときに沈めとチューブに、必要です。</li>
		<li>ゆっくりとピペットの脱イオン水反応マイクロ遠心チューブ用のトップに。50 mL の円錐管の脱イオン水でいっぱいで遠心管を水没し、ゲルを許可する遠心チューブからのスライドします。</li>
		<li>24 時間、脱イオン水でゲルを残し、12 h で水を取り替えます。ゲルと接触する液体メニスカスを許可しないでください。</li>
	</ol>
</li>
</ol>2. 電気化学的面積 (ECSA) 湿式金属ゲル特性
注: 電気化学的特性評価は、凍結乾燥を行う前に濡れた金属ゲルで実行されます。結果 ECSA、最終的なエアロゲル構造の表面の推定値になります。窒素吸着測定を用いて乾燥エアロゲル表面積を推定する.
<ol><li>
溶媒交換。<ol>
<li>Au から脱イオン水の多くを削除、Pd, Pt 可能なソリューションをすすいでくださいし、液体のメニスカスは、ゲルを接触しないことを確認します。</li>
		<li>50 mL の 0.5 M 支持電解質ゲルの細孔内に脱イオン水を交換するために円錐形のチューブに KCl を追加します。24 h KCl 溶液、ゲルを残します。</li>
	</ol>
</li>
	<li>
働く電極の準備。
	<ol>
<li>1 mm の白金線電極を微細毛ブラシまたは公開ワイヤ先端の 4-5 の mm 長さを残して他のアプリケーション デバイスを使用して非反応性のラッカーでコートします。</li>
		<li>漆乾燥に 20 分を許可します。</li>
		<li>ラッカーの少なくとも 2 つのコートを適用します。</li>
	</ol>
</li>
	<li>
3 電極セルを設置しました。
	<ol>
<li>3 電極セルの設定を使用して、Ag/agcl (飽和 3 M) と電極、0.5 mm 径 Pt 線補助/カウンター電極、ラッカー コーティング作用電極を参照します。</li>
		<li>プラスチック製 50 mL コニカル チューブを半分にカットし、電気化学のバイアルとして使用します。</li>
		<li>2 つの方法の 1 つと作用電極とゲルの接触: 1) impaled ゲル、または 2) 接触モード。<ol>
<li>
電極 - impaled ゲルを使用します。<ol>
<li>変更された 50 mL の円錐管の下部にゲル、ゲル ラッカー コーティング電極そっと挿入します。 注: impaled ゲル法を Pd, Pt ゲル電極挿入時より頻繁の破壊に対し Au ゲルでより効果的な証明します。</li>
			</ol>
</li>
			<li>
働く電極 - コンタクト モード。<ol>
<li>内面に沿って円錐管にラッカー コーティング作用電極を挿入し、作用電極の露出 Pt 線の上に金属のゲルを置きます。</li>
			</ol>
</li>
		</ol>
</li>
	</ol>
</li>
	<li>
電気化学インピー ダンス分光法 (EIS)。<ol>
<li>定 100 MHz と 10 mV の振幅の正弦波を用いた 1 mHz の間の周波数で EIS をスキャンを実行します。現在オーバーフローが発生した場合、同じ周波数範囲 100-200 mA 振幅正弦波と定電流 EIS を使用します。</li>
	</ol>
</li>
	<li>
電気化学的面積 (ECSA) EIS データからの決定。<ol>
<li>Z"、1 mHz、サンプルの質量、 m、除算の最低の EIS 周波数fでのインピー ダンスの虚数部Csp、特定の容量を決定する次の式を使用します。 Csp = 1/(2 πfZ"m) (1) 注: ことを考えると、ECSA は湿潤ゲル前からステップ 3 以下のフリーズドライを決意し、ゲルを形成する金属イオン濃度のすべてが減少した質量が決定します。この仮定に基づく、100% よりも小さい任意の実際の収量になります Cspを過小評価しています。</li>
	</ol>
</li>
	<li>
サイクリックボルタンメトリー (CV)。<ol>
<li>CV 測定用 100、75、50、25、10、5、1 mV/秒のスキャン レートを使用します。Au ゲルの (対銀/塩化銀)-0.2 0.2 V の電圧範囲を使用し、水素の吸着と脱離・金属の酸化還元を避けるために Pd, Pt ジェルの 0.1 から 0.4 V を選択します。</li>
	</ol>
</li>
	<li>
電気化学的面積 (ECSA) 履歴書データからの決定。<ol>
<li>1 mV/s の遅い CV スキャン レートを使用し、方程式の固有容量を計算します。 Csp = (∫ivdv)/(2μmΔV) (2) 注: ここで私とvは現在と CV スキャン (A と V) の潜在的なスキャン レートはμ (V ・ s)、ジェルの質量はm (g)、 ΔV放電 (対銀/塩化銀) の潜在的な窓であります。</li>
	</ol>
</li>
</ol>3. エアロゲルの調製とキャラクタリゼーション。
<ol><li>ステップ 1.8 Au, Pd, Pt のゲルを脱イオン洗浄水を削除し、水のメニスカスは、金属のゲルに接触しないことを確認します。</li>
	<li>凍結乾燥機の 4 接点圧力で 30 分以上転送冷凍金属ゲル ゲル-80 ° C のフリーザーの場所 Pa または低い。</li>
</ol>

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I. 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>

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金属エアロゲルの合成法は、低速の合成技術に匹敵する多孔質で高表面積モノリスの急速な形成の結果を紹介しました。還元剤ソリューション比に 1:1 (v/v) 金属イオン溶液が提案ゲル形成モデルを促進する上で重要です。金属イオンの電気化学的還元の副産物として急速な水素ガスはセカンダリ還元剤として機能し、緻密化、およびゲル形成過程におけるナノ粒子の成長の融合が容易になり?...

エネルギー貯蔵・変換、触媒、センサーの用途の広い範囲の恩恵を化学反応と物質移動特性1,2、制御を提供する三次元金属ナノ構造体 3,4,5。このような 3 次元金属ナノ構造さらには、導電性、延性、展性、強度8,9を強化します。デバイスへの統合には、フリースタンディングまたはサポート材料と複合材料であることが必要となります。サポート構造体にナノ材料の取り込み活物質を最小限に抑える手段を提供しますが、弱い吸着と最終的な集積デバイス操作10,11の間に苦しむことがあります。
個々 のナノ粒子のサイズと形状を制御する合成法の様々 ないくつかのアプローチは連続した 3 次元ナノ材料12,13,14制御を有効にします。ジチオール単分散ナノ粒子、ゾル-ゲル形成、ナノ粒子の合体、複合材料、ナノ粒子チェーン、biotemplating15,16の連携による貴金属 3 次元ナノ構造が形成されています。,17,18. これらのアプローチの多くは、数日から数週間ご希望の材料を生成するための順序の合成時間を必要とします。貴金属 nanofoams 前駆体塩溶液の還元から合成される高速合成スケールと数百 μ m の長さの短距離秩序に用意されているが、デバイス統合の押す機械を必要とします。19,20。
キスラーによって報告された最初、エアロゲルは、桁違いのバルク材料対応21,22,23より密度が低く、高い比表面積を持つ多孔質の構造を達成するために合成ルートを提供します。.バルク材料の巨視的長さスケールを 3 次元構造を拡張するナノ粒子凝集体または nanofoams サポート材料や機械加工を必要とする以上の利点を提供しています。エアロゲルは、合成時間を拡張気孔率と粒子径の機能、ただし、制御への合成ルートを提供しながら、いくつかのエージェントまたはリンカー分子、全体的な処理の手順と時間の増加の上限の使用をケースします。
ここで急速に、直接ソリューション ベースの還元によるエアロゲルはプラチナ、パラジウム、金を合成する方法には、24が表示されます。1:1 の還元剤と様々 な前駆体金属イオンを組み合わせること (v/v) 比数秒 ~ 数分以内金属ゲルの形成に比べてゾル-ゲルなど他の技術の合成時間が長いくらい。提案の核形成、成長、緻密化、融合、ゲル形成のための平衡モデルを促進する削減ステップの副産物として積極的な水素ガスの微量遠心チューブまたは少量の円錐管の使用を活用します。エアロゲルのナノ構造機能サイズに密接な相関関係は、走査型電子顕微鏡画像の解析、x 線回折、窒素ガス吸着、電気化学インピー ダンス分光法、サイクリックボルタンメトリーで決まります。電気化学インピー ダンス分光法とサイクリックボルタンメトリー溶剤アクセス可能な表面積が決定されます。金属エアロゲルのこの合成法では、その高い比表面積のモノリスは、急速に、直接削減アプローチと達成されるかもしれないを示します。

<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

ここでは、金、パラジウム、および急速に、直接ソリューション ベースの減少によってプラチナ エアロゲルを合成する手法を提案します。数秒 ~ 数分以内金属ゲルの形成に 1:1 (v/v) 比の結果の還元剤に様々 な前駆体金属イオンの組み合わせは、ゾル-ゲルなど他の技術の多く合成時間が長いと比較。遠心機の削減ステップを行う管または少量の円錐管提案の核形成、成長、緻密化、融合、最終的なゲル ジオメトリの最初の反応量よりも小さいと、ゲル形成のための平衡モデルを促進します。このメソッドは、削減ステップの試薬濃度の結果としての副産物として積極的な水素ガスの利点を受け取ります。電気化学インピー ダンス分光法とサイクリックボルタンメトリー溶剤アクセス可能な表面積が決定されます。洗浄と凍結乾燥、走査電子顕微鏡、x 線回折法と窒素ガス吸着の結果のエアロゲルの構造が調べられます。合成手法と評価手法は、エアロゲル靭帯サイズの近い対応。金属エアロゲルのこの合成法では、その高い比表面積のモノリスは、急速に、直接削減アプローチと達成されるかもしれないを示します。

一緒に金属イオン、還元剤液の添加はすぐに積極的なガス発生濃いブラック色のソリューションの結果します。反応の進行の観察では、図 1に示すように, ゲル形成機構を示唆しています。ゲル形成 1) ナノ粒子の核形成、成長 2)、3) 緻密化、4) 融合、5) 平衡の 5 つのステップを通過します。最初の 4 つの手順に従って平衡ゲルが還元剤の溶液中?...

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

Au、Pd、およびソリューションに基づく還元を介して Pt エアロゲルの迅速合成法

Au, Pd, Pt のエアロゲルを取得するソリューション ベースの削減が急速に、直接合成する方法が表示されます。

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 ビュー.  United States Military Academy, West Point. Au, Pd, Pt のエアロゲルを取得するソリューション ベースの削減が急速に、直接合成する方法が表示されます。

ビデオ: 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.

急速な超臨界抽出方法によるシリカエアロゲルモノリスを準備

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

化学

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.

プロパン脱水素のためのPt-Cu固溶体ナノ粒子触媒の合成と試験

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.

急速な超臨界抽出法によって作製した触媒のエアロゲルの作製と試験

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.

金属ナノ粒子の正確に制御された沈着量の連続的な流れの光触媒反応

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.

セルロースナノファイバーバイオテンプレートパラジウム複合エアロゲルの合成法

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.

表面プラズモン励起によるコロイドAuナノロッドへのPdの光堆積

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.

多孔質白金ベースマクロビームおよびマクロチューブの塩鋳合成法

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.

可視光照明下におけるプラスモニック触媒のための銀パラジウム合金ナノ粒子の調製

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.

レーザーエッチングと染料の組み込みによる美的強化シリカ・アエロゲル

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

工学

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.

アルケンおよびアルデヒドの水素化反応におけるチタニアに担持されたアミン安定化および配位子フリー白金ナノ粒子における触媒反応

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