19.02.2009
РОССИЙСКАЯ АКАДЕМИЯ НАУК

УРАЛЬСКОЕ ОТДЕЛЕНИЕ

ИНСТИТУТ ХИМИИ TBEPДОГО ТЕЛА
   
| | | | |
| | | | | |
 19.02.2009   Карта сайта     Language По-русски По-английски
Новые материалы
Экология
Электротехника и обработка материалов
Медицина
Статистика публикаций


19.02.2009



Single nanocatalyst behaviour revealed



18 February 2009



Before you can design the perfect nanoparticle catalyst, you first need to understand the fundamental science that governs their reactivity, say scientists from the US. And they claim to have done just that, using single molecule spectroscopy to reveal that nanocatalyst surface properties respond to changes to the concentration of reactants. 


The team led by Peng Chen at Cornell University, Ithaca, have devised a technique for studying the catalytic properties of individual gold nanoparticles - which gets around the traditional problem with studying nanocatalysts, says Chen. 'No matter how good a synthetic chemist you are, the nanoparticles you make will have slightly different sizes and shapes, and this is why you need to study one particle at a time, so you don't have to average all of them.'


Using single molecule fluorescence, Chen could 'watch' single nanoparticles react with single reactants, and quantify the heterogeneity between different particles. 'We knew nanoparticle behaviours were different among at population, but just how different they are has been challenging to quantify before now,' says Chen.


However, while studying the catalytic redox conversion of resazurin to resorufin, the team also found that each nanoparticle changes its surface catalytic properties in response to the concentration of reactants. 'This has never been discovered before,' says Chen. 'We found that nanoparticles surfaces can change from "type A" to "type B", and these two types have different reactivities. Type B that occurs at high concentrations is more reactive and binds to reactants weakly, and type A that occurs at low concentrations is lower in reactivity and binds to the reactants strongly.' It is not yet understood, however, why the switching of behaviours occurs.


The ultimate nanocatalysis would be designed to combine these two types of behaviour, says Chen. 'Ideally you want a nanoparticle that binds to the reactant strongly so you can scavenge all the reactants from solution, and you also want reactivity to be high so the catalysis goes faster.' 


Look closer


Robert Rioux, an expert in heterogeneous catalysis at Pennsylvania State University, US, says that Chen's findings 'will have vast implications in terms of designing catalysts'. 'Studies like these will be critical for the design of the materials and understanding how catalysts behave under reaction conditions,' he adds. 


Until last year - when two new techniques were announced - the catalytic properties of nanoparticles couldn't be studied on a single molecule level. One of these is Chen's, and the other, which uses surface plasmon resonance (SPR) spectroscopy, was designed by Paul Mulvaney at the University of Melbourne, Australia. Chen says that the main advantage of his technique is that it 'can monitor reactions one reaction at a time, and count reactions in real time. And Mulvaney's technique can not do this.'


Another advantage of Chen's technique, explains Rioux, is that unlike SPR spectroscopy it can be used for any type of metal nanoparticle - not just SPR-responsive metals such as gold and silver. 


Next Chen plans to make use of this advantage and switch from studying gold to platinum nanoparticles - as he feels a better understanding of these is could help for fuel cell applications.


Nina Notman


 


Interesting story? Spread the word using the 'tools' menu on the left.



References


 




Probing the catalytic activity and heterogeneity of Au-nanoparticles at the single-molecule level
Weilin Xu, Jason S. Kong and Peng Chen, Phys. Chem. Chem. Phys., 2009
DOI: 10.1039/b820052a


Дизайн и программирование N-Studio 
А Б В Г Д Е Ё Ж З И Й К Л М Н О П Р С Т У Ф Х Ц Ч Ш Щ Ъ Ы Ь Э Ю Я
  • Chen Wev   honorary member of ISSC science council

  • Harton Vladislav Vadim  honorary member of ISSC science council

  • Lichtenstain Alexandr Iosif  honorary member of ISSC science council

  • Novikov Dimirtii Leonid  honorary member of ISSC science council

  • Yakushev Mikhail Vasilii  honorary member of ISSC science council

  • © 2004-2024 ИХТТ УрО РАН
    беременность, мода, красота, здоровье, диеты, женский журнал, здоровье детей, здоровье ребенка, красота и здоровье, жизнь и здоровье, секреты красоты, воспитание ребенка рождение ребенка,пол ребенка,воспитание ребенка,ребенок дошкольного возраста, дети дошкольного возраста,грудной ребенок,обучение ребенка,родить ребенка,загадки для детей,здоровье ребенка,зачатие ребенка,второй ребенок,определение пола ребенка,будущий ребенок медицина, клиники и больницы, болезни, врач, лечение, доктор, наркология, спид, вич, алкоголизм православные знакомства, православный сайт творчeства, православные рассказы, плохие мысли, православные психологи рождение ребенка,пол ребенка,воспитание ребенка,ребенок дошкольного возраста, дети дошкольного возраста,грудной ребенок,обучение ребенка,родить ребенка,загадки для детей,здоровье ребенка,зачатие ребенка,второй ребенок,определение пола ребенка,будущий ребенок