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A molecular platform for heterogeneous OER electrocatalysis based on double-atom catalysts

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Operando XAS examine of Ni–Fe–N–C. a. This analysis crew devised a platform of double-atom catalysts for basic research of heterogeneous OER electrocatalysts, offering a mannequin of complete operando research on how atomic-configuration and chemical state can have an effect on their ensuing catalytic nature. Even although the idea of bifunctional catalysis in OER is proposed in just a few primarily theoretical papers, this work offers the primary experimental demonstration of a secure and non-precious double-atom catalyst that’s superior to the very best standard catalysts. The crew thinks their work might encourage quite a few follow-up research using double-atom catalysis as a brand new design technique, resulting in the following technology of superior OER catalysts. Credit: Bai et al.

The oxygen evolution response (OER) is a chemical response that permits the technology of oxygen fuel. This response is essential for producing fuels by water splitting or by the electroreduction of CO2.

So far, combined metallic oxides containing Co, Fe or Ni have been discovered to be probably the most promising electrocatalysts for eliciting this response. However, on account of their heterogeneity, these catalysts and their response mechanisms will be tough to review.

In latest years, scientists have additionally been carefully inspecting atomically dispersed catalysts, an rising class of heterogeneous electrocatalysts with a excessive atomic effectivity, which embody and discrete sub-nano clusters. This new kind of catalyst is characterised by uniform and well-defined lively websites, which is likely to be simpler to probe and look at.

Researchers at Ecole Polytechnique Federale de Lausanne (EPFL) and National Taiwan University have just lately launched a brand new molecular platform that may very well be used to immediate and examine heterogeneous OER electrocatalysis. This platform, launched in a paper printed in Nature Energy, is based on double-atom catalysts, catalysts through which all lively metallic species exist as two outlined atoms.

“Although a few atomically dispersed OER catalysts were recently reported, the structures of their during OER remained unclear,” Hao Ming Chen, one of many researchers who carried out the examine, informed TechXplore. “In our previous work, we showed that we could transform a single-atom Co pre-catalyst into a Co-Fe double atom catalyst for OER in-situ. This catalyst exhibits one of the highest turnover frequencies among metal oxides.”

Using a way generally known as operando X-ray absorption spectroscopy (XAS), Chen and his colleagues confirmed that the lively web site of the catalyst they created was a dimeric Co-Fe moiety. Their findings finally proved the potential of double-atom molecular platforms for the event of outlined and extremely lively OER catalysts.

“We believe that one of the most important subjects in heterogeneous oxygen evolution electrocatalysis today is to develop new approaches that facilitate the understanding of active heterogeneous catalysts,” Chen mentioned. “However, in our previous work, we only demonstrated the Co-Fe double-atom catalysts.”

To show the general effectiveness of double-atom catalysts for heterogeneous OER electrocatalysis, the researchers confirmed that the transformation into double-atom catalysts is feasible for Co, Fe, and Ni containing single-atom pre-catalysts. They thus created varied double-atom catalysts and characterised their buildings utilizing operando XAS and high-energy-resolution fluorescence detected (HERFD) XAS. In addition, they examined them utilizing a technique generally known as aberration-corrected scanning transmission electron microscopy evaluation.

“These iso-structural and defined catalysts provide a rare molecular framework for the mechanistic study of heterogeneous OER catalysts,” Chen mentioned. “The double-atom catalysts presented here can be considered as molecular models of the active site of mixed metal oxides, which are among the most active catalysts for OER.”

The latest work by Chen and his colleagues introduces double-atom catalysts as a brand new worthwhile platform for OER catalysis. In addition, the researchers outlined a easy and simple methodology for synthesizing these catalysts.

“By utilizing operando X-ray absorption studies and performing electrokinetic analyses on all catalysts, we can deduce catalytic cycles for OER, which is extremely challenging and has not been realized to date,” Chen mentioned. “Because our catalysts have molecularly defined active site, they bridge molecular and heterogeneous solid-state catalysts. The corresponding mechanistic study should have a far-reaching impact.”

In the long run, the brand new molecular platform proposed by this crew of researchers may very well be used to review heterogenous OER electrocatalysts extra in depth. For occasion, it might assist materials scientists to higher perceive how a ‘s atomic configuration and chemical state have an effect on its catalytic nature.

“We believe that our work will inspire numerous follow-up studies employing double-atom catalysis as a new design strategy and may also be applicable to other heterogeneous electrocatalysts,” Chen added. “For example, in the electrochemical CO2 reduction, it can be speculated that the C-C coupling has to occur on the catalytic surface to form the C-C bonding formation for generating C2 products, such as C2H4 and C2H5OH. We are planning to develop the double-atom electrocatalysts for heterogeneous electrochemical CO2 reduction.”


Large-scale synthesis strategies for single-atom catalysts for alkaline gasoline cells


More info:
Lichen Bai et al, Double-atom catalysts as a molecular platform for heterogeneous oxygen evolution electrocatalysis, Nature Energy (2021). DOI: 10.1038/s41560-021-00925-3

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A molecular platform for heterogeneous OER electrocatalysis based on double-atom catalysts (2021, December 1)
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