High surface area alumina aerogel at elevated temperatures

Abstract Single-atom catalysts (SACs) exhibit unique catalytic property and maximum atom efficiency of rare, expensive metals. A critical barrier to applications of SACs is sintering of active metal atoms under operating conditions. Anchoring metal atoms onto oxide supports via strong metal-support bonds may alleviate sintering. Such an approach, however, usually comes at a cost: stabilization results from passivation of metal sites by excessive oxygen ligation—too many open coordination sites taken up by the support, too few left for catalytic action. Furthermore, when such stabilized metal atoms are activated by reduction at elevated temperatures they become unlinked and so move and sinter, leading to loss of catalytic function. We report a new strategy, confining atomically dispersed metal atoms onto functional oxide nanoclusters (denoted as nanoglues) that are isolated and immobilized on a robust, high-surface-area support—so that metal atoms do not sinter under conditions of catalyst activation and/or operation. High-number-density, ultra-small and defective CeOx nanoclusters were grafted onto high-surface-area SiO2 as nanoglues to host atomically dispersed Pt. The Pt atoms remained on the CeOx nanoglue islands under both O2 and H2 environment at high temperatures. Activation of CeOx supported Pt atoms increased the turnover frequency for CO oxidation by 150 times. The exceptional stability under reductive conditions is attributed to the much stronger affinity of Pt atoms for CeOx than for SiO2—the Pt atoms can move but they are confined to their respective nanoglue islands, preventing formation of larger Pt particles. The strategy of using functional nanoglues to confine atomically dispersed metal atoms and simultaneously enhance catalytic performance of localized metal atoms is general and takes SACs one major step closer to practical applications as robust catalysts for a wide range of catalytic transformations

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Converting Stöber Silica and Mediterranean Sand to High Surface Area Silicon by a Reaction under Autogenic Pressure at Elevated Temperatures

The Journal of Physical Chemistry C ◽

10.1021/jp809432t ◽

2009 ◽

Vol 113 (24) ◽

pp. 10521-10526 ◽

Cited By ~ 37

Author(s):

N. H. Hai ◽

I. Grigoriants ◽

A. Gedanken

Keyword(s):

Surface Area ◽

Elevated Temperatures ◽

High Surface ◽

High Surface Area

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2021 F. M. Becket Fellowship – Summary Report Measuring Transient Electrochemistry of Lithium Metal Anodes under Varying External Stack Pressures

The Electrochemical Society Interface ◽

10.1149/2.f06214if ◽

2021 ◽

Vol 30 (4) ◽

pp. 32-33

Author(s):

Wesley Chang

Keyword(s):

Surface Area ◽

Elevated Temperatures ◽

High Surface ◽

High Surface Area ◽

Lithium Metal ◽

Summary Report ◽

Electrochemical Reactivity ◽

Lithium Metal Anodes ◽

Area Deposition ◽

Metal Anodes

Lithium metal anodes are challenged by the inherent chemical and electrochemical reactivity of lithium metal, which is further exacerbated by non-uniform high surface area deposition. Recently, lithium difluoro(oxalato)borate (LiDFOB) salt coupled with a fluorinated solvent has been demonstrated to result in densely deposited lithium morphology along with high Coulombic efficiencies due to a stable solidelectrolyte-interphase. Along with other newly discovered electrolyte compositions for stable lithium deposition, these studies typically utilize high stack pressures and elevated temperatures. These developments are promising, and would further benefit from a study that maps out the effects of varying stack pressure and temperature on lithium anode mechanics, chemistry, and electrochemistry.

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Tenacious Mass Transfer Limitations Drive Catalytic Selectivity during Electrochemical Carbon Dioxide Reduction

10.26434/chemrxiv.7770338.v1 ◽

2019 ◽

Cited By ~ 1

Author(s):

Kailun Yang ◽

Recep Kas ◽

Wilson A. Smith

Keyword(s):

Surface Area ◽

High Surface ◽

High Surface Area ◽

Catalyst Layer ◽

Active Surface ◽

Active Surface Area ◽

High Concentration ◽

Copper Electrodes ◽

Surface Enhanced ◽

Local Current

This study evaluated the performance of the commonly used strong buffer electrolytes, i.e. phosphate buffers, during CO2 electroreduction in neutral pH conditions by using in-situ surface enhanced infrared absorption spectroscopy (SEIRAS). Unfortunately, the buffers break down a lot faster than anticipated which has serious implications on many studies in the literature such as selectivity and kinetic analysis of the electrocatalysts. Increasing electrolyte concentration, surprisingly, did not extend the potential window of the phosphate buffers due to dramatic increase in hydrogen evolution reaction. Even high concentration phosphate buffers (1 M) break down within the potentials (-1 V vs RHE) where hydrocarbons are formed on copper electrodes. We have extended the discussion to high surface area electrodes by evaluating electrodes composed of copper nanowires. We would like highlight that it is not possible to cope with high local current densities on these high surface area electrodes by using high buffer capacity solutions and the CO2 electrocatalysts are needed to be evaluated by casting thin nanoparticle films onto inert substrates as commonly employed in fuel cell reactions and up to now scarcely employed in CO2 electroreduction. In addition, we underscore that normalization of the electrocatalytic activity to the electrochemical active surface area is not the ultimate solution due to concentration gradient along the catalyst layer.This will “underestimate” the activity of high surface electrocatalyst and the degree of underestimation will depend on the thickness, porosity and morphology of the catalyst layer.

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Rugae-like FeP nanocrystal assembly on a carbon cloth: an exceptionally efficient and stable cathode for hydrogen evolution

Nanoscale ◽

10.1039/c5nr02375k ◽

2015 ◽

Vol 7 (25) ◽

pp. 10974-10981 ◽

Cited By ~ 95

Author(s):

Xiulin Yang ◽

Ang-Yu Lu ◽

Yihan Zhu ◽

Shixiong Min ◽

Mohamed Nejib Hedhili ◽

...

Keyword(s):

Gas Phase ◽

Surface Area ◽

Hydrogen Evolution ◽

Hydrogen Generation ◽

High Surface ◽

High Surface Area ◽

Catalytic Efficiency ◽

Carbon Cloth ◽

Nanocrystal Assembly

High surface area FeP nanosheets on a carbon cloth were prepared by gas phase phosphidation of electroplated FeOOH, which exhibit exceptionally high catalytic efficiency and stability for hydrogen generation.

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