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Recently, Professor Liu Detao and his team from South China University of TechnologyA new method has been developed to improve the efficiency of electrosynthetic hydroperoxide production.

In the study, the research team started from the molecular, nano, millimeter and other material scales, and provided a new development path for the design of a new generation of biomass-based 2e electrocatalytic materials.

After optimizing the gas diffusion electrode preparation method, the team found that the synthesis yield of hydroperoxide could reach 510.58 mg·L -1 ·cm -2 ·h -1 .

This yield is dozens of times higher than that of other biomass carbon-based catalytic materials currently available, and is also several times higher than that of petroleum carbon-based catalytic materials.

Figure | Group photo (Source: Data map)

Nanocellulose is the main object of this study. It has the advantages of high porosity and high specific surface area, and can be used to coordinate three-dimensional aerogel structures with oxygen-containing functional groups.

By utilizing the special metal ion coordination on the surface of one-dimensional nanocellulose and combining it with freeze-drying technology, a material called "zeolite imidazole skeleton-nanocellulose foam" can be created.

The material has a bright purple appearance and a relatively stable structure. After carbonization and other processes, it can produce abundant oxygen capture active sites.

Figure | Nanocellulose-zeolite imidazole framework-nanocellulose foam aerogel sample synthesized by cobalt coordination (Source: Small)

Moreover, it can also form a nano-composite cobalt tetroxide structure, which is very beneficial to improving the efficiency of electron migration, thereby improving the efficiency of electrosynthesized hydrogen peroxide generation.

In the study, the team also designed a dual-cathode electro-Fenton technology device, which has the ability to synergize.It can decompose common organic pollutants with high efficiency, with a removal rate of 99.43% within 30 minutes.

For other wastewaters such as aquaculture wastewater, paint wastewater, papermaking wastewater, etc., this technology can also achieve efficient and rapid pollution removal and purification functions.

Therefore, it is very promising to replace the existing chemical disinfection tablet technology and play a role in healthy drinking water and outdoor portable water purification and disinfection.

It is reported that as an extremely important green chemical, hydrogen peroxide has broad application prospects in semiconductors, healthcare, environmental control, fine chemicals and other fields.

At present, in the industrial-scale production of hydroperoxides, people mainly use a method called "anthraquinone method".

It has problems such as high cost, complex operation, environmental pollution, and unsafe transportation and storage, which makes it difficult to use in wild and remote areas.

The 2e−ORR electrochemical method for synthesizing hydroperoxides is not only easy to operate and has high production efficiency, but also has excellent electrochemical stability, making it particularly suitable for some portable application scenarios.

However, most of the current cathode electrocatalysts often rely on precious metals and petroleum carbon-based materials, which are not only limited by the supply of raw materials but also incur high economic costs.

However, the current global utilization of renewable biomass cellulose resources provides a very valuable opportunity for the development of next-generation alternative cathode materials. At the same time, these materials have the advantages of low price, wide supply, and ecological protection.

However, for existing biomass-derived 2e electrocatalysts, satisfactory hydroperoxide production efficiency has not been achieved due to problems such as few carbon defects, insufficient oxygen vacancies, and poor electron transfer ability.

Therefore, designing a biomass-based 2-electron electrocatalytic material that can be used for the efficient electrochemical synthesis of hydroperoxides has important practical significance and can achieve important application prospects in the fields of disinfection and advanced oxidation technology.

(Source: Small)

As mentioned above, nanocellulose plays an important role in this project. Biomass nanocellulose is not only abundant in nature, but also renewable.

Qian Zhiyun, a master's student in the team, started working on material screening and structural design as soon as he received the project.

She has made many attempts, from micron-grade cellulose powder to dissolved regenerated cellulose to ordinary paper fiber, but has not been able to achieve good results.

Later, she began to try to improve the 2e selectivity of nanocellulose and increase the yield of hydroperoxide at the molecular and nanoscale.

The surface of nanocellulose contains a large number of hydrophilic oxygen-containing groups, and its specific surface area is also relatively large.

At the molecular level, hydrophilic cellulose microfibrils or nanofibrils have a large number of oxygen-containing hydroxyl groups and cellulose molecular chains with sub-nanometer sizes.

Based on the above advantages, they can be easily surface functionalized, so that the functional structure of cellulose at the nanoscale or microscale can also be artificially adjusted.

Figure | Structural diagram (Source: Small)

Based on this, by cobalt-coordinating one-dimensional nanocellulose, a zeolite imidazole skeleton-nanocellulose foam with a nanostructure can be directly grown around the nanocellulose.

At the same time, Qian Zhiyun and others used nanocellulose aerogel as the substrate. For zeolite imidazole framework-nanocellulose foam nanoparticles, the advantage of doing so is that it can achieve uniform growth on the surface of nanocellulose.

In addition, these nanoparticles are able to achieve tight interconnection, which ensures the dimensional stability of the original structure without any falling off and deformation.

Through this, cobalt-nanocellulose aerogel samples can be made using a simple and low-cost method.

Figure | Catalyst microstructure (Source: Small)

Subsequently, by using molecular engineering and high-temperature pyrolysis, the above samples can fully generate high oxygen capture active sites within the dense nanocellulose network structure.

At this point, electrons can be transferred along the nanostructured cobalt tetroxide anchored on the one-dimensional biochar, resulting in excellent hydroperoxide yields.

Figure | Hydroperoxide synthesis yield and Faraday effect (Source: Small)

In general, from the initial directionless exploration to the design of metal coordination molecular engineering, the team has made nanocellulose, a biocarbon resource, realize its great potential.

Recently, a related paper titled "Scalable Cathodic H2O2 Electrosynthesis using Cobalt-Coordinated Nanocellulose Electrocatalyst" was published in Small (IF 13).

Figure | Related papers (Source: Small)

Qian Zhiyun, a master's student at South China University of Technology, is the first author, and Professor Liu Detao is the corresponding author.

Figure | Qian Zhiyun, the first author of the paper (Source: Data map)

It is reported that electrochemical synthesis is an ancient yet novel key technology. It is simple and efficient, green and safe, low-cost and easy to scale up, showing very attractive commercial value.

Over the years, Chinese scientists have solved many technical challenges that are difficult to overcome by other methods by developing new electrochemical synthesis technologies.

Many previous technological achievements have been applied on a large scale, providing new solutions to common technical problems in the industry.

Functional materials, including cathodes and anodes, have always been the key core of electrochemical synthesis, and to a certain extent determine the efficiency, cost and working life of electrochemical synthesis.

Therefore, the continuous research and development of new alternative high-performance electrocatalytic materials is a goal that scientific researchers have always pursued.

Therefore, in the future, the team will focus on the modification of cellulose molecules to prepare some new high-level 2e-ORR materials.

In order to reduce costs and simplify the preparation process, they will also carry out industry-university-research cooperation with external companies to put the thesis into practice and solve the bottleneck problems in the development of the industry.

"At present, many companies have called and visited us looking for cooperation," said the researchers.

References:

1.Qian, Z., Liu, D., Liu, D., Luo, Y., Ji, W., Wang, Y., ... & Duan, Y. (2024). Scalable Cathodic H2O2 Electrosynthesis using Cobalt‐Coordinated Nanocellulose Electrocatalyst.Small, 2403947.

Layout: Chu Jiashi

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