When Ange Nzihou, an expert in converting public waste into useful products, visited Princeton in 2022, he brought with him a method to convert waste biomass into graphene (Green Graphene Secret Revealed), a material with many uses, from batteries to solar cells. He knows that his method of using non-toxic metals offers advantages over existing methods that rely on dangerous chemicals, precious metals or fossil fuels.
There’s just one problem: Nzihou doesn’t know exactly how the system works.
Nzihou, distinguished professor of chemical engineering at IMT Mines Albi – CNRS in France said, “In my work as a chemical engineer, I am interested in the final properties of materials and how they are applied in the real world attended Princeton as part of the Fulbright Visiting Scholar Program. “But if you want to improve the properties of the things you create, you need to understand what’s happening at the nano and atomic scales to make that change.”
That’s where Claire White, assistant professor of civil and environmental engineering at the Andlinger Center for Energy and the Environment, steps in to help.
As a visiting faculty member, White brings her expertise in nanoscale and atomic-scale characterization to unravel the process that helped iron-assisted conversion of waste biomass into graphene.
The result was not only two papers, the first published in ChemSusChem and the other in Applied Nano Materials, which detailed the process and promise of using iron as a catalyst to transform biomass free, such as woodchips and other biomass rich in cellulose, and useful carbonaceous matter. It is also the first demonstration for an ongoing collaboration between the two groups, which combines the expertise of each group to add new dimensions to their research activities.
Detection of nanometric parameters
Graphene, a sheet of pure carbon only one atom thick, is made by chemical etching, a process commonly used in the semiconductor industry to produce single layers. However, Nzihou said the installation of air chemicals often relies on dangerous chemicals and expensive technology. Similarly, he said that alternative methods for graphene production often use toxic or cost-limiting materials, as well as the use of petroleum-based fuels.
In search of an environmentally friendly way to produce graphene, Nzihou and White turned to unused biomass sources as feedstock for the process. Unfortunately, most of this biomass is rich in cellulose, a rich polymer found in plant cell walls. Cellulose has proven difficult to convert into a solid carbonaceous material such as graphene without using toxic metals or rare earths due to the structure and composition of its chemical bonds.
But Nzihou discovered that metal oxide catalysts could do the trick. By adding iron to the biomass and heating it with oxygen through a process known as carbonization, Nzihou demonstrated that it is possible to transform the cellulose-containing biomass into a final material with a large area of graphene sheets. law.
“Ange has shown that it is possible to use iron as a catalyst,” White said. “But the real question is trying to understand how iron provides this catalytic behavior.”
White turned to his expertise in atomic and nanoscale properties to find the answer. Using methods such as total X-ray scattering, Raman spectroscopy, transmission electron microscopy, and magnetic measurements, researchers found that during the heating process, the iron oxide catalyst breaks down d first to produce nanoparticles and biomass. As the cellulose-rich biomass begins to melt at high temperatures, it rises as a sheet of graphene on top of the metal surface.
“We can see the ordered carbon shell that forms around these metal nanoparticles during this process,” White said.
Interestingly, Nzihou and White found that a few heavy metal nanoparticles support a large area of graphene formation rather than many small ones, a useful clue that can inform future efforts cost-free biomass conversion process. and graphene. Researchers continue to refine the process to make the graphene area purer and reduce the number of defects in the final product.
Nzihou said, “Now that we understand the process, we can determine how to improve this process and improve the properties of graphene sheets compared to the conventional process of liquid medicine, and even consider ways to increase it in the near future.” “Because ultimately our mission is to create a high carbon product that is environmentally friendly and closes the carbon loop and reduces carbon dioxide emissions.”
A primer for fruitful collaboration
The researchers said the project helped them leverage each other’s expertise to advance the field of sustainable carbon use, and the initial collaboration has led to several ongoing research projects.
“It’s an exciting partnership,” White said. “I would never see myself working with these carbon-sustainable materials, but these projects with Ange provided a great opportunity to expand my work and add new dimensions to my research.”
For Nzihou, his time as a Fulbright visiting scholar is just a glimpse of what is to come. It will return to the Andlinger Center in March 2024 as Gerhard R. Andlinger Visiting Fellow to continue researching ways to convert low-value biomass sources into high-carbonaceous materials with specific properties for applications ranging from agriculture to energy storage and CO2 processes.
At White, he plans to expand his scope of work by combining the expertise of other Princeton faculty members such as Craig Arnold, Michele Sarazen and Rodney Priestley to develop strategies for sustainable carbon use. He is also looking to collaborate with the Princeton Plasma Physics Laboratory (PPPL) to explore the use of plasma to power various manufacturing processes.
“I believe that the carbon research we are doing will have a great impact, because there are still many exciting challenges to overcome in the field,” said Nzihou. I believe Princeton is the right place to do it. When I saw the organization of the Andlinger Center, I saw that it had everything I needed to develop my research.
Source: Princeton University
