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

저자는 그의 영감과 기술 통찰력, Aerogel 기술에서 스티븐 스타 이너와 육군 연구 실험실-센서와 전자 장치 스파이, 군비 연구, 박사 크리스토퍼 하인즈 박사 Deryn 추 감사 개발 및 엔지니어링 센터, ARDEC-미국 육군 RDECOM, 및 그들의 지원에 대 한 미국 육군 Benet 실험실에서 박사 스티븐 Bartolucci 이 작업을 지원 했다 미국 미국 육군 사관 학교, 웨스트 포인트에서에서 교수 개발 연구 기금 교부 금에 의해.

주의: 사용 하기 전에 모든 관련 안전 데이터 시트 (SDS)를 참조 하십시오. 증기 두건 및 개인 보호 장비를 사용 하 여 포함 하도록 적절 한 안전 관행 화학 반응, 수행할 때 사용 합니다. 급속 한 수소 가스 진화 팝 캡을 일으키는 반응 튜브 및 밖으로 스프레이 솔루션에서 높은 압력을 발생할 수 있습니다. 반응 관 모자 프로토콜에 지정 된 대로 열어 확인 합니다.
1. 금속 젤 준비
<ol><li>
금속 이온 솔루션의 준비입니다.
	<ol>
<li>다음 소금의 0.1 M 솔루션의 2 개 mL를 준비: HAuCl4•3H2O와 나2PdCl4 에서 저온. 준비 2 mL의 0.1 M K2PtCl6 1:1 (v/v)에 물과 에탄올 용 매. 적극적으로 악수와 소용돌이 솔루션 소금의 해산에 도움.</li>
	</ol>
</li>
	<li>
감소 에이전트 솔루션의 준비입니다.
	<ol>
<li>다음 감소 시키는 대리인의 0.1 M 솔루션의 10 mL를 준비: dimethylamine borane (DMAB)와 NaBH4 (나트륨 borohydride).</li>
	</ol>
</li>
	<li>
Au의 준비 젤.
	<ol>
<li>1.7 mL 또는 2.0 mL microcentrifuge 관으로 0.1 m M HAuCl4•3H2O 솔루션의 0.5 mL를 플라스틱. 소금 및 감소 에이전트 솔루션의 빠른 조합을 보장 하기 위해 골드 솔루션 microcentrifuge 튜브에 DMAB의 0.5 mL를 플라스틱 강제로. 일단 솔루션은 혼합 장소 microcentrifuge 튜브 튜브 캡 튜브 랙에 수직으로 엽니다. 참고: 경우 튜브 캡 마감, 수소 가스 진화 뚜껑 팝 열기를 강제 하 고 잠재적으로 감소 혼합물 스프레이를 내부 압력을 발생 합니다.</li>
	</ol>
</li>
	<li>
Pd의 준비 젤.
	<ol>
<li>1.7 mL 또는 2.0 mL microcentrifuge 관으로 0.1 m M 나2PdCl4 솔루션의 0.5 mL를 플라스틱. 강제로 팔라듐 솔루션 microcentrifuge 튜브에 NaBH4 의 0.5 mL를 플라스틱. 장소 microcentrifuge 튜브 튜브 캡 튜브 랙에 수직으로 엽니다.</li>
	</ol>
</li>
	<li>
Pt 준비 젤.
	<ol>
<li>1.7 mL 또는 2.0 mL microcentrifuge 튜브로 0.1 M K2PtCl6 솔루션의 0.5 mL를 플라스틱. 강제로 플래티넘 솔루션 microcentrifuge 튜브에 DMAB의 0.5 mL를 플라스틱. 장소 microcentrifuge 튜브 튜브 캡 튜브 랙에 수직으로 엽니다.</li>
	</ol>
</li>
	<li>
반전 관.
	<ol>
<li>약 5 분, microcentrifuge 튜브 뚜껑과 부드럽게 3-5 시간을 반전 금속 젤의 일부가 아닌 금속 입자의 접착에 도움. 확인 튜브, 반전 후 세척제는 튜브 캡은 즉시 및 바꾸기 튜브 튜브의 수직 방향 유지 선반에.</li>
	</ol>
</li>
	<li>
재래식.<ol>
<li>동안 Au, Pd, Pt 젤 처음 몇 분 안에 형성, 금속 이온의 완전 한 감소 및 표면 자유 에너지를 최소화를 위한 3-6 h 원제 솔루션에서 초기 젤을 둡니다. 참고: 금속 젤 혼합된 금속 이온 및 환 원제 솔루션의 초기 볼륨 보다 작은 볼륨을 차지합니다. 몇 가지 추가적인 약간의 볼륨 수축 평형 시간 동안 관찰 될 수 있습니다 그리고 더 골드 젤에 대 한 발음 이며 오 스 트 발트25숙성 인 것으로.</li>
	</ol>
</li>
	<li>
젤 rinsing.<ol>
<li>재래식 기간 후 Au, Pd, Pt 젤, 초과 감소 에이전트 솔루션을 제거 하지만 금속 젤 침수 되도록 충분 한 솔루션 볼륨을 둡니다. 솔루션 초승달 모양 금속 젤 연락 오지 않는다 있는지 확인 합니다. 참고: 비록 젤은 주걱, 모 세관으로 솔루션 사이의 전송 충분히 안정적인 금속 세력 솔루션 초승달 모양 접촉으로 인해 변형 되며 젤 마지막 aerogel 밀도 증가에 따른 압축. 이 일부 감소 에이전트 솔루션 빠져들 때 전송 저온 젤 튜브에 남아 해야 합니다.</li>
		<li>천천히 반응 microcentrifuge 튜브의 상단에 이온된 물 플라스틱. 이온된 수의 전체 50 mL 원뿔 튜브에 microcentrifuge 튜브 잠수함 고 microcentrifuge 튜브 슬라이드 젤.</li>
		<li>24 h에 대 한 이온된 수에 젤 두고 12 h 물 대체. 젤과 접촉 하는 액체 초승달을 허용 하지 마십시오.</li>
	</ol>
</li>
</ol>2. 전기 화학 표면 영역 (ECSA) 젖은 금속 젤의 특성
참고: 전기 화학 특성 젖은 금속 젤 동결 건조를 실시 이전에 수행 됩니다. 결과 ECSA 다음 최종 aerogel 구조의 표면의 예상 시간입니다. 질소 흡착 측정 말린된 aerogels의 노출 영역을 추정 하는 데 사용 됩니다.
<ol><li>
용 매 교환.<ol>
<li>Au에서 이온된 수의 제거, Pd, 및 태평양 표준시 가능한 솔루션 린스 액체 초승달 모양 젤 연락 오지 않는 확인 하십시오.</li>
		<li>50 mL, 0.5 M KCl 지원 젤 모 공 내의 전해질 이온된 수를 교환 하려면 원뿔 관에 추가 합니다. 24 h를 위한 KCl 해결책에 있는 젤을 둡니다.</li>
	</ol>
</li>
	<li>
작업 전극 준비입니다.
	<ol>
<li>좋은 브러쉬 또는 노출 하는 와이어 끝의 4-5 m m 길이 떠나 다른 응용 프로그램 장치를 사용 하 여 비 반응성 래커로 플래티넘 1 m m 와이어 전극 코트.</li>
		<li>건조 래커에 대 일 분을 허용 합니다.</li>
		<li>옻 칠의 적어도 2 개의 외 투를 적용 하십시오.</li>
	</ol>
</li>
	<li>
3 전극 셀 설정 했다입니다.
	<ol>
<li>3 전극 셀 설정 Ag/AgCl (3m 포화)와 함께 사용 하 여 참조 전극는 0.5 m m 직경 Pt 와이어 보조/카운터 전극 및 래커 코팅된 작업 전극.</li>
		<li>플라스틱 50 mL 원뿔 튜브 반으로 잘라 고 전기 유리병으로 사용 합니다.</li>
		<li>두 가지 방법 중 하나로 작업 전극과 젤 문의: 1) 찔 려 젤, 또는 2) 연락처 모드.<ol>
<li>
작업 전극-찔 려 젤.<ol>
<li>수정 된 50 mL 원뿔 튜브의 하단에 젤으로 부드럽게 삽입 래커 코팅된 전극 젤. 반면 Pd 및 Pt 젤 전극 삽입 시 더 자주 골절 참고: 찔 젤 방법 Au 젤, 더 효과적인 증명 한다.</li>
			</ol>
</li>
			<li>
작업 전극-모드 문의입니다.<ol>
<li>래커 코팅된 작업 전극 내부 표면 따라 원뿔 관으로 삽입 하 고 나머지 작업 전극의 노출된 Pt 와이어 위에 금속 젤.</li>
			</ol>
</li>
		</ol>
</li>
	</ol>
</li>
	<li>
전기 화학 임피던스 분광학 (EIS)입니다.<ol>
<li>Potentiostatic EIS 100 MHz와 10 mV 진폭 사인파를 사용 하 여 1 mHz 사이의 주파수를 사용 하 여 검색을 수행 합니다. 현재 오버플로 경우 동일한 주파수 범위는 100-200 mA 진폭 사인파와 galvanostatic EIS를 사용 합니다.</li>
	</ol>
</li>
	<li>
EIS 데이터에서 전기 화학 표면 영역 (ECSA)의 결정.<ol>
<li>대 한 Z ", 1mhz, 그리고 샘플 질량, m, 분할의 최저 EIS 주파수 f 에서 임피던스의 허수부 다음 방정식 결정 특정 커패시턴스, Csp를 사용 하 여: C sp = 1 / (2 πfZ "m) (1) 참고: 아래 3 단계에서에서 건조 동결 하는 ECSA 젖은 젤 사전에서 결정을 모든 솔루션에서 금속 이온의 젤을 형성 하기 위하여 감소 된다 가정 하 여 질량을 결정 합니다. 이 가정에 따라, 100% 미만 어떤 실제 수익률 발생 합니다 Csp를 과소 평가.</li>
	</ol>
</li>
	<li>
주기적 voltammetry (CV)입니다.<ol>
<li>100, 75, 50, 25, 10, 5, 및 1 mV/s의 스캔 속도 사용 하 여 CV 측정. Au 젤에 대 한 (vs Ag/AgCl)-0.2 0.2 V의 전압 범위를 사용 하 고 0.4에 0.1 V 수소 흡착 및 탈 착, 및 금속의 oxidation-reduction을 피하기 위해 Pd 및 Pt 젤에 대 한 선택.</li>
	</ol>
</li>
	<li>
이력서 데이터에서 전기 화학 표면 영역 (ECSA)의 결정.<ol>
<li>1 mV/s의 느린 이력서 스캔 속도 사용 하 고 특정 커패시턴스는 방정식을 계산: C sp = (∫ivdv) / (2μmΔV) (2) 참고: 여기 i 와 v 는 전류와 잠재력 (A와 V) 이력서 검색, 스캔 속도 μ (V/s), 젤의 질량은 m (g) 이며 δ 는 방전 (vs Ag/AgCl)의 잠재적인 창입니다.</li>
	</ol>
</li>
</ol>3. Aerogel 준비와 특성입니다.
<ol><li>단계 1.8에서 Au, Pd, Pt 젤에 대 한 이온된 린스 물을 제거 하 고 물 초승달 모양 금속 젤 연락 오지 않는다 합니다.</li>
	<li>이상 30 분 전송 냉동된 금속 4의 세트 포인트 압력으로 건조 기 동결으로 젤은 젤-80 ° C 냉동 고에 장소 Pa 또는 낮은.</li>
</ol>

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저자는 공개 없다.

고귀한 금속 aerogel 합성 방법 느린 합성 기법에 버금가 다공성, 높은 표면적 monoliths의 급속 한 형성에 결과 여기 발표. 감소 에이전트 솔루션 비율을 1:1 (v/v) 금속 이온 솔루션 제안된 젤 형성 모델을 용이 하 게 중요 하다. 금속 이온의 전기 화학 감소의 결과로 급속 한 수소 가스 진화 보조 원제 역할 densification, 그리고 젤 형성 동안 성장 하는 나노 입자의 융합을 촉진 한다. 표 1 에 표?...

에너지 저장 및 변환, 촉매, 센서 응용 프로그램의 다양 한 화학 반응성, 및 대량 전송 속성1,2,제어를 제공 하는 3 차원 금속 nanostructures에서 혜택 3,,45. 이러한 3 차원 금속 nanostructures 추가 향상 전도도, 연 성가 단성, 그리고 강도8,9. 장치에 통합 자료 무료 서 또는 지원 자료와 결합 된 것 필요로 한다. 지원 구조에 나노 재료의 활성 소재, 최소화 하는 수단을 제공 하지만 약한 흡착 및 장치 작업10,11동안 궁극적인 덩어리에서 고통을 수 있습니다.
다양 한 합성 방법 개별 나노 입자 크기와 모양을 제어 하는, 몇 가지 접근 연속 3 차원 나노 소재12,,1314제어 가능 고귀한 금속 3 차원 nanostructures의 단 분산 나노 입자, 졸-겔 형성, 나노 접착, 복합 재료, 나노, 체인과 biotemplating15,16 dithiol 결합을 통해 형성 된 , 17 , 18. 이러한 방법의 많은 합성 시간 일 원하는 자료를 주 순서 필요. 선구자 소금 솔루션의 직접적인 감소에서 합성 하는 고귀한 금속 nanofoams 길이, 마이크로미터의 수백의 단거리 순서와 빠른 합성 날짜 표시줄 함께 준비 된 하지만 기계 장치 통합을 위한 눌러 필요 19 , 20.
Kistler에 의해 처음 보고, aerogels 높은 특정 표면 영역 크기 순서 그들의 대량 소재 대응21,,2223 보다 적게 조밀한과 다공성 구조를 달성 하기 위해 합성 경로 제공 . 벌크 재료의 거시적인 길이 규모에 3 차원 구조를 확장 나노 집계 또는 지원 자료 또는 기계 가공을 필요로 하는 nanofoams에 이점을 제공 합니다. 그러나 Aerogels 제공 다공성 및 입자 기능 크기,, 제어 합성 경로 확장 합성 시간, 그리고 일부 경우 대리인 또는 링커 분자, 증가 전반적인 처리 단계 및 시간 상한의 사용.
여기 금, 팔라듐, 그리고 신속 하 고 직접적인 솔루션 기반 감소를 통해 플래티넘 aerogels를 합성 하는 방법24를제공 됩니다. 1: 1에서 감소 시키는 대리인으로 다양 한 전조 고귀한 금속 이온을 결합 분 초 이내 금속 젤의 형성에 (v/v) 비 결과 비교 솔-젤 같은 다른 기술에 대 한 합성 시간이 훨씬 더 오래. Microcentrifuge 튜브 또는 작은 볼륨 원뿔 튜브의 사용 감소 단계 촉진 제안된 nucleation, 성장, densification, 퓨전, 젤 형성에 대 한 평형 모델의 부산물로 서 활발 한 수소 가스 진화를 활용 합니다. Aerogel nanostructure 기능 크기에 가까운 상관 전자 현미경 이미지 분석, x 선 diffractometry, 질소 가스 흡착, 전기 화학 임피던스 분광학, 및 순환 voltammetry 스캔으로 결정 됩니다. 솔벤트 액세스할 수 특정 표면 영역 전기 화학 임피던스 분광학 및 주기적 voltammetry 결정 됩니다. 이 합성 방법 고귀한 금속 aerogels monoliths는 신속 하 고 직접적인 감소 방식으로 얻을 수 있습니다 그 높은 특정 표면 영역을 보여 줍니다.

<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

여기, 금, 팔라듐, 그리고 신속 하 고 직접적인 솔루션 기반 감소를 통해 플래티넘 aerogels를 합성 하는 방법을 제시 합니다. 감소 시키는 대리인 분 초 이내 금속 젤의 형성에서 1:1 (v/v) 비율 결과에 다양 한 전조 고귀한 금속 이온의 조합에 비해 솔-젤 같은 다른 기술에 대 한 합성 시간이 훨씬 더 오래. microcentrifuge에서 감소 단계를 실시 튜브 또는 작은 볼륨 원뿔 튜브 용이 제안된 nucleation, 성장, densification, 퓨전, 젤 형성, 초기 반응 볼륨 보다 작은 마지막 젤 형상에 대 한 평형 모델. 이 메서드는 부산물로 감소 단계, 그리고 시 약 농도 결과로 서 활발 한 수소 가스의 활용. 솔벤트 액세스할 수 특정 표면 영역 전기 화학 임피던스 분광학 및 주기적 voltammetry 결정 됩니다. 헹 구 고 동결 건조, 후 스캐닝 전자 현미경, x 선 diffractometry, 및 질소 가스 흡착과 결과 aerogel 구조를 검사 합니다. 합성 방법 및 특성화 기술 결과에 가까운 통신 aerogel 인 대 크기의. 이 합성 방법 고귀한 금속 aerogels monoliths는 신속 하 고 직접적인 감소 방식으로 얻을 수 있습니다 그 높은 특정 표면 영역을 보여 줍니다.

금속 이온과 환 원제 솔루션 함께 결과의 즉시 격렬 한 가스 발전으로 어두운 블랙 색상을 선회 하는 솔루션에 추가. 반응 진행의 그림 1에 표시 된 제안 된 젤 형성 메커니즘을 제안 합니다. 젤 대형 1) 나노 nucleation, 2) 성장, 3) densification, 4) 융합, 및 5) 평형의 5 단계까지 진행합니다. 처음 네 단계는 반응, 평형 젤 원제 솔루션에 남아 하 고 이온된 수 ?...

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

Au, Pd, Pt Aerogels 직접 솔루션 기반 감소를 통해 빠른 합성 방법

Au, Pd, Pt aerogels를 신속 하 고 직접적인 솔루션 기반 감소 합성 방법은 제공 됩니다.

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 조회수.  United States Military Academy, West Point. Au, Pd, Pt aerogels를 신속 하 고 직접적인 솔루션 기반 감소 합성 방법은 제공 됩니다.

비디오: 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.

빠른 초 임계 추출 방법을 통해 실리카 에어로젤, 모노 리드 (monolith)를 준비

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

연구

화학

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.

프로판 탈수 소화를위한 Pt-Cu 고용체 나노 입자 촉매 합성 및 시험

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.

제조 및 급속 한 초 임계 추출 통해 준비 촉매 Aerogels의 테스트

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.

금속 나노 입자의 정확 하 게 제어 증 착에 대 한 연속 흐름 촉매 반응 기

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.

셀룰로오스 나노 섬유 바이오 템플릿 팔라듐 복합 에어로겔에 대한 합성 방법

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.

표면 플라스몬 여기에 의해 콜로이드 Au 나노로드에 Pd의 포토포지션

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.

다공성 플래티넘 기반 매크로빔 및 매크로튜브용 염식 합성 방법

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.

가시광선 조명 아래 플라스모닉 촉매용 실버 팔라듐 합금 나노 입자 의 준비

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.

레이저 에칭과 염료의 통합을 통해 미학적으로 향상된 실리카 에어로겔

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

공학

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.

알켄과 알데히드의 수소화 동안 티타니아에 지지된 아민 안정화 및 리간드가 없는 백금 나노입자에서의 촉매 반응

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