At present, we are applying this catalyst to commercial scenarios. The co-first author of this paper has already established a startup company and has obtained financing to build a commercial-grade reactor based on this catalytic system, thereby achieving large-scale production of electrocatalytic carbon dioxide to methanol.

Zhejiang University undergraduate alumnus and Ohio State University Ph.D. graduate Zhu Quansong (who has now returned to China to take up a position) said:

Through this research, he and his collaborators have highlighted the importance of uniformly dispersing molecular catalysts in a single molecular state on the catalyst support.

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In the past, people mainly focused on synthesizing molecular catalysts with better performance. However, this study proves that dispersing molecular catalysts as much as possible on the support is equally important.

The reason is that in the natural state, molecular catalysts are prone to aggregation. Previously, people did not pay enough attention to this issue and believed that dispersion would only increase the electrochemical active area.The study presented here, however, indicates that there is more to it than that: namely, dispersion can increase the coupling interaction with the cations within the Stern layer, thereby producing different selectivities.

As a simple chemical strategy, the advantage of the dispersion strategy over the synthesis strategy lies in the fact that the same effect can be achieved even without using more expensive and better catalysts.

Moreover, in this study, Zhu Quansong and others not only tested the electrocatalytic reduction of carbon dioxide but also tested the electrocatalytic reduction of oxygen and nitrate reduction.

Through this, it was found that single-molecule dispersion can increase the selectivity and activity of catalysis, thus bringing universal guidance to heterogeneous molecular electrocatalytic systems.

Further understanding of heterogeneous molecular electrocatalytic systems.It is reported that using renewable energy to generate electrical energy to catalyze the reduction of carbon dioxide is a sustainable way to prepare carbon-based chemicals, and it is also a potential effective way to achieve "carbon neutrality". The electrocatalyst is the key to this transformation.

Heterogeneous molecular electrocatalysts are a new type of catalyst that has emerged in recent years. It can achieve electrocatalysis by loading molecular catalysts on conductive carriers, thus achieving the combination of homogeneous catalysis and heterogeneous catalysis.

For heterogeneous molecular electrocatalysts, it can retain the respective advantages of homogeneous and heterogeneous catalysis at the same time. Not only is the reaction rate high, but the products and catalysts are also easier to separate.

At the same time, the structure of each catalytic active site is uniform, so it can achieve efficient operation, and it is easy to be modified and adjusted.

In 2019, Professor Hailiang Wang of Yale University in the United States reported a cobalt phthalocyanine/carbon nanotube heterogeneous molecular catalyst, and the relevant paper was published in Nature[1].When the cobalt phthalocyanine molecule is dispersed uniformly on multi-walled carbon nanotubes in an approximate monomeric state, the heterogeneous electrocatalyst can effectively reduce carbon dioxide to methanol.

At the same time, it can achieve selectivity of more than 40% and activity greater than 10 mA/cm². After modification with amino groups, it can still maintain stability for more than 12 hours.

However, when this cobalt phthalocyanine catalyst is mixed with carbon nanotubes in a multi-molecular aggregated state, the main products are carbon monoxide and hydrogen, with only a very small amount of methanol produced.

That is to say: when the same molecular catalyst is distributed on the same carrier in different dispersion forms, it can produce such a huge difference in catalytic performance.

This significant difference has attracted the attention of Zhu Quansong and his doctoral supervisor, and has also facilitated their cooperation with the team of Hailiang Wang from Yale University.Zhu Quansong stated that if an answer to this question can be found, it will lead to a deeper understanding of heterogeneous molecular electrocatalytic systems, thereby laying a theoretical foundation for the application of heterogeneous molecular catalysis.

For many years, Zhu Quansong's research group during his doctoral studies has accumulated a wealth of experience in nonlinear in-situ spectroscopy technology.

Sum frequency vibrational spectroscopy technology is highly selective for interfaces. Therefore, they decided to use this technology to study the interfacial process.

The guidance of the mentor is indispensable.In addition to the team Zhu Quansong was part of at the time and the Yale University team participating in this research, this study also brought together collaborators from the State University of New York and the Hebrew University of Israel.

The Yale University team was responsible for conducting research on the catalytic performance of dispersed and aggregated cobalt phthalocyanine catalysts.

The Hebrew University team was primarily responsible for characterizing the state of cobalt phthalocyanine molecules using atomic force microscopy-infrared technology.

During the research, Zhu Quansong and the team he was part of at the time were responsible for using sum frequency vibrational spectroscopy technology to conduct in situ studies on the reaction mechanism of cobalt phthalocyanine molecules.

During this period, he used the reflective configuration spectroelectrochemical cell independently built by the team he was part of at the time. This cell allows the laser to reflect from the back of the electrode without having to pass directly through the electrolyte, and can also perform in situ tests by applying voltage.Although this configuration can avoid the restriction on the thickness of the electrolyte layer, thus enabling true in-situ research,

however, it must rely on the plasma enhancement effect, that is, a specific metal thin film with surface plasmon enhancement effect must be used as the substrate, only in this way can sufficient gain be achieved for the signal.

Thus, how to load the heterogeneous molecular catalyst cobalt phthalocyanine/carbon nanotubes onto the metal thin film substrate for testing is one of the problems encountered by Zhu Quansong.

He found that: the gold and copper thin films commonly used by people before have a strong adsorption effect on the reaction intermediates, that is, on the carbon monoxide molecules.

This leads to easy interference with the spectrum, so that it is impossible to determine whether the observed carbon monoxide signal comes from the substrate thin film or from the heterogeneous molecular catalyst.Later, Zhu Quansong used an ultra-thin layer of aluminum oxide to perform surface passivation treatment on the silver film substrate, which ensured conductivity while avoiding interference from the substrate to the signal.

Subsequently, he confirmed the differences in spectral results between dispersed cobalt phthalocyanine and aggregated cobalt phthalocyanine, and proposed a theoretical speculation.

To further verify the above speculation, collaborators from the State University of New York began theoretical calculations. Through a large number of density functional calculations, the rationality of the speculation was confirmed.

That is: the active and inactive CO signals of methanol come from the single-molecule state cobalt phthalocyanine adsorbed in the Stern layer, and the aggregated cobalt phthalocyanine located in the Diffuse layer, respectively.

This further led to the following conclusion: that cations may couple with the CO reaction intermediates in the Stern layer, thereby reducing the reaction barrier and promoting the reduction of CO to methanol.To verify the impact of cations on the heterogeneous molecular electrocatalytic system, Zhu Quansong and his collaborators conducted research on catalysis and spectroscopy for lithium ions and potassium ions complexed with crown ethers.

By testing different electrolyte compositions, they found that the electrolyte also affects the catalytic performance of the reaction, and this effect occurs by changing the solvation structure at the interface.

This once again confirms their speculation: that the carbon monoxide intermediate in the Stern layer is the true active intermediate.

The solvation structure of the Stern layer, which is the cation composition, has a significant impact on its activity, which in turn affects the yield of methanol.

Of course, the successful completion of this study is also inseparable from the timely guidance of Zhu Quansong's mentor.After observing different spectra from the dispersed and aggregated cobalt phthalocyanines, I spent a long time pondering and trying to understand the spectral results, but I could not come up with a good explanation, said Zhu Quansong.

At that time, the mentor gave such a reminder: "Perhaps it can be considered from the different positions of the double electric layer, as well as from the presence or absence of hydrogen bonds."

The strategy of aluminum oxide surface passivation used by Zhu Quansong was also an idea proposed by the mentor. "His opinion profoundly inspired me and played an important role in the completion of this work," said Zhu Quansong.

Recently, the related paper was published in Nature Catalysis (IF 42.8) with the title "The solvation environment of molecularly dispersed cobalt phthalocyanine determines methanol selectivity during electrocatalytic CO2 reduction."

Zhu Quansong is the first author, Professor Julien A. Panetier from the State University of New York, Professor Elad Gross from the Hebrew University of Israel, Hailiang Wang from Yale University, and Professor L. Robert Baker from Ohio State University served as co-corresponding authors [2].It is also reported that this study was funded by the National Science Foundation of the United States and the U.S.-Israel Binational Science Foundation.

Furthermore, Zhu Quansong and others have found that different functional group modifications of cobalt phthalocyanine molecules can bring about different stabilities. For instance, the stability of amino groups is significantly enhanced.

Therefore, they plan to conduct more in-depth research on the failure mechanism of this system in the next step.

For example, by conducting in-situ spectroscopic studies, they aim to better understand the impact of each functional group in order to optimize the reaction system more effectively.