Atomic view of a chemical catalyst during electrically charged reaction is a scientific first – Technology Org

There are products all around us that depend on chemical reactions aided by electricity.

These electrochemical reactions are involved in the manufacturing of everything from aluminum and PVC pipes to soap and paper. They’re inside batteries that power electronics, automobiles, pacemakers and other things. And they may hold the key to the sustainable production of energy and other resources on which society depends.

At left, a red arrow tracks the movement of an individual copper atom during an electrochemical reaction. On the right, yellow arrows point to pits left behind in the catalyst surface. Image credit: Qiubo Zhang/Lawrence Berkeley National Laboratory

Catalysts such as copper help drive reactions, so they are used in most industrial applications of electrochemistry. Efforts to develop better catalysts have been hampered because what happens to these catalysts during reactions is poorly understood. Until now, atomic imaging of catalysts could only be done before and after reactions, leaving researchers to figure out what happened in between.

That limitation has been overcome thanks to cooperation between California Nanosystems Institute at UCLA And Lawrence Berkeley National Laboratory. one in new study Published in the journal Nature, the team used a specially designed electrochemical cell to look at the atomic details of a copper catalyst during a reaction that breaks down carbon dioxide – a greenhouse gas that can be recycled into fuel or other useful substances. One possible way to do it. Scientists documented a liquid-like mass of copper appearing and disappearing on the catalyst surface, causing it to crater.

“For so much of what we have in our lives, we actually understand very little about how catalysts work in real time,” said co-author Dr. Dear Narang, Professor of Physics at UCLA College and in Electrical and Computer Engineering UCLA Samueli School of Engineering. “We now have the ability to see what is happening at the atomic level and understand it from a theoretical perspective.

“Turning carbon dioxide directly into fuel would benefit everyone, but how do we do it, and how do we do it cheaply, reliably, and at scale?” Added Narang, who is also a CNSI member. “This is the kind of fundamental science that should move the needle in addressing those challenges.”

Beyond the implications for sustainability research, these findings – and the technology that makes them possible – could advance the efficiency of electrochemical processes for many applications affecting everyday life. According to the co-author, the study could help scientists and engineers move toward rational catalyst design instead of trial and error. Yu Huang, Traugott and Dorothea Frederiking is Professor and Chair of the Department of Materials Science and Engineering at UCLA Samuel.

“Any information we can gain about what actually happens in electrocatalysis is a tremendous help in our fundamental understanding and exploration of practical designs,” said CNSI member Huang. “Without that information, it’s like we’re throwing darts blindfolded, and hoping we’ll hit somewhere close to the target.”

Images captured at Berkeley Lab molecular foundry With a high-power electron microscope. This type of microscope uses a beam of electrons to look inside samples at a level of detail smaller than the length of the light wave.

Electron microscopy has moved into barriers revealing the atomic structure of materials working in liquids – such as the glowing electrolyte bath required for an electrochemical reaction. Running electricity through a sample further increases the degree of difficulty. Corresponding author Haimei Zheng, a senior scientist at Berkeley Lab and assistant professor at UC Berkeley, and her colleagues created a hermetically sealed device that overcomes these obstacles.

The researchers conducted experiments to eliminate the possibility that electricity running through the system was affecting the resulting image. Focusing on the spot where the copper catalyst met the liquid electrolyte, the team captured the changes that occurred in about four seconds.

During the reaction, the structure of the copper changed from an ordered crystal lattice, usually seen in metals, to an amorphous mass. That disordered bundle, which included copper atoms and positively charged ions and a few water molecules, then flowed onto the catalyst surface. As it did so, atoms were exchanged between the ordered and disorganized copper, causing the surface of the catalyst to become brittle. Finally, the amorphous mass disappeared.

“We never expected that the surface would become amorphous and then return to the crystalline structure,” said co-author Yang Liu, a UCLA graduate student in Huang’s research group. “Without this special equipment to observe the operation of the system, we would never have been able to capture that moment. Advances in such characterization tools enable new fundamental discoveries, helping us understand how materials work under realistic conditions.

Co-first authors of the study are Qiubo Zhang and Jianhu Sun of Berkeley Lab, and Zhigang Song, a member of Narang’s research group who is based at Harvard University. Other co-authors from Berkeley Lab are Sophia Betzler, Qi Zheng, Junyi Shangguan, Karen Bustillo and Peter Arcius, as well as Jiawei Wan, also affiliated with UC Berkeley.

The Department of Energy provided funding for this study, as well as the molecular foundry at Berkeley Lab.

written by wayne lewis

Source: UCLA