More efficient photocatalysts for new green technologies

Foto: pulses of visible light (blue) excite a silver nanoparticle; the electron transfer to the surrounding oxide is studied by means of ultra-short and intense (yellow) X-ray pulses generated by the free electron laser (courtesy of S.Pelli Cresi)


Modena - 22.03.2021 - More efficient photocatalysts for new green technologies

Rome, March 22, 2021

A study conducted by CnrNano researchers in collaboration with University of Modena and Reggio Emilia, University of Bologna, Cnr-ISM, Cnr-IOM, and Elettra Sincrotrone Trieste investigates the ultra-fast electron transfer process within materials for photocatalysis. The results, published in Nano Letters, will help develop novel hybrid photocatalysts for environmental and energy applications

Researchers coordinated by Paola Luches of Cnr-Nano, studied hybrid photocatalysts consisting of metal nanoparticles combined with semiconductor oxides. In these materials the nanoparticles absorb light through collective oscillations of electrons, known as plasmonic resonances, and transfer the absorbed energy to the oxide with a mechanism not fully understood, although fundamental to determine the good or bad efficiency of the catalyst. "We have now shown that metal nanoparticles transfer electrons to the oxide through an ultra-fast and very efficient process, which occurs within 200 femtoseconds (1 femtosecond is equal to one millionth of a billionth of a second) from the moment the light is absorbed" says Paola Luches of Cnr-Nano.
Such precise measurements were made possible thanks to one of the most advanced instruments: the FERMI free electron laser from Elettra Sincrotrone Trieste. "A unique light source worldwide, capable of emitting extremely short and intense pulses in the X-ray range that make it the brightest and most powerful probe to study dynamic processes" says Stefano Pelli Cresi of Elettra Sincrotrone Trieste, first author of the Research. "FERMI has made it possible to study for the first time the dynamics of energy transfer between nanoparticles and semiconductors thanks to a technique that is extremely sensitive to chemistry and with a very high temporal resolution", explains Daniele Catone of Cnr-Ism.
These finding will help develop materials with better photoreactivity to be used for technologies in the environmental field, such as in applications such as water splitting ti produce hydrogen, and CO2 reduction, and water purification.
This research began by traveling between the laboratories of Modena, Rome and Trieste and ended by adapting to the restrictions imposed by the pandemic. "Access to the FERMI laser in Trieste is extremely limited, given its uniqueness. The second measure was scheduled for the first days of March 2020, but we were forced to cancel the trip a few hours from the start of the experiment, which took place for the first time in smart mode. The success was possible thanks to the determination and skills of the FERMI staff who made it possible to implement a remote contact system in a recordi time already during the first Italian lockdown ", says Luches.



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