Chemical reactions powered by electricity are essential for the production of various products in industries.
Manufacturing of aluminum, PVC pipe, soap, and paper relies on these electrochemical reactions, which are also integral to the functioning of batteries in electronic devices, cars, pacemakers, and more. Furthermore, they have the potential to revolutionize sustainable energy production and resource utilization.
Copper and similar catalysts play a crucial role in driving these reactions and are extensively used in industrial electrochemistry applications. However, the lack of understanding about the behavior of catalysts during reactions has hindered the development of improved catalysts. Until now, researchers have only been able to image catalysts before and after reactions, leaving a gap in comprehending the processes that occur in between.
A collaboration between the California NanoSystems Institute at UCLA and Lawrence Berkeley National Laboratory has eliminated that limitation. The team utilized a specially engineered electrochemical cell to observe the atomic structure of a copper catalyst during a reaction that decomposes carbon dioxide.
This method poses a potential avenue for converting the greenhouse gas into fuel or other valuable substances. The researchers recorded instances of copper forming liquid-like masses and then vanishing at the surface of the catalyst, resulting in noticeable pitting.
“For something that is all over our lives, we actually understand very little about how catalysts work in real-time,” said co-author Pri Narang, a professor of physical sciences at UCLA College and a CNSI member. “We now have the ability to look at what’s happening at an atomic level and understand it from a theoretical standpoint.
“Everyone would benefit from turning carbon dioxide straight to fuel, but how do we do it, and do it cheaply, reliably, and at scale?” added Narang, who also holds an appointment in electrical and computer engineering at the UCLA Samueli School of Engineering. “This is the type of fundamental science that should move the needle in addressing those challenges.”
The discoveries in sustainability research carry significant implications, and the technology enabling these findings has the potential to improve the effectiveness of electrochemical processes across various applications that affect daily life.
According to Yu Huang, co-author of the study and the Traugott and Dorothea Frederking Endowed Professor and chair of the materials science and engineering department at UCLA Samueli, the study may assist scientists and engineers in transitioning from trial and error to a more systematic catalyst design approach.
“Any information we can get about what really happens in electrocatalysis is a tremendous help in our fundamental understanding and search for practical designs,” said Huang, who is a member of the CNSI. “Without that information, it’s as if we’re throwing darts blindfolded, and hoping that we hit somewhere close to the target.”
High-power electron microscope at Berkeley Lab’s Molecular Foundry was used to capture images. This microscope utilizes a beam of electrons to delve into samples with a level of detail smaller than the length of a light wave.
Challenges have been encountered in electron microscopy when attempting to uncover the atomic structure of materials in liquid environments, such as the briny electrolyte bath required for an electrochemical reaction.
Adding electricity to a sample further complicates the process. Haimei Zheng, the corresponding author, a senior scientist at Berkeley Lab and adjunct professor at UC Berkeley, and her colleagues developed a hermetically sealed device to overcome these obstacles.
The scientists carried out tests to ensure that the flow of electricity in the system did not impact the resulting image. Focusing on the specific location where the copper catalyst met the liquid electrolyte, the team recorded the changes that occurred over approximately four seconds.
Throughout the reaction, the structure of the copper transitioned from a regular crystal lattice, commonly found in metals, to an irregular mass. This unordered bundle, composed of copper atoms and positively charged ions along with a few water molecules, then moved across the catalyst surface. While doing so, atoms were swapped between the regular and irregular copper, resulting in the pitting of the catalyst surface. Eventually, the irregular mass vanished.
“We never expected the surface to turn amorphous and then return back to the crystalline structure,” said co-author Yang Liu, a UCLA graduate student in Huang’s research group. “Without this special tool for watching the system in operation, we would never be able to capture that moment. The advancement of characterization tools like this enables new fundamental discoveries, helping us understand how materials work under realistic conditions.”
Journal reference:
- Qiubo Zhang, Zhigang Song, Xianhu Sun, Yang Liu, Jiawei Wan, Sophia B. Betzler, Qi Zheng, Junyi Shangguan, Karen C. Bustillo, Peter Ercius, Prineha Narang, Yu Huang & Haimei Zheng. Atomic dynamics of electrified solid–liquid interfaces in liquid-cell TEM. Nature, 2024; DOI: 10.1038/s41586-024-07479-w