"Nothing but joy." When Liu Guangdong saw the news that his paper had been officially accepted by Nature in the research group's WeChat group, the '90s-born researcher couldn't help but smile with happiness. In that moment, the years of anxious struggles flashed through his mind, especially the lowest point when his mentor, Professor Deng Huiqiu from Hunan University, candidly encouraged him, pulling him out of the rut.
"We've made it through. 2023 was a year of harvest, getting married and having a child. May 2024 continue to bring us small joys and hopes." This was Liu Guangdong's New Year's wish posted on his social media on the last day of the previous year. Little did he know that it would come true so soon.
On February 29th, the research findings were formally published online, confirming the specificity of surface stress-driven reaction activity, indicating that in the field of catalysis, no two reaction sites have exactly the same activity. Deng Huiqiu told Chinese Science Bulletin: "During the initial review, the paper was recommended by a reviewer who suggested, 'The paper can be accepted for publication in Nature without any revisions,' but from initial submission to actual publication, it took three years."
Deng Huiqiu (left) and Liu Guangdong (right) at the National Supercomputing Center in Changsha. Photo by Wang Haohao.
Unveiling Catalytic Truths with a "Super Magnifying Glass"
The German philosopher Leibniz once said, "There are no two leaves alike in the world." This emphasizes the uniqueness among things.
In the realm of chemical catalysis, are there two active sites that are completely identical in activity? Until recently, scientists didn't have an answer to this question.
Deng Huiqiu, who has been deeply engaged in fields such as material microstructure and its performance relationship for over 20 years, naturally became interested in this question. He prefers to outline research directions and allow students to explore freely based on their interests. In 2017, Liu Guangdong, a second-year master's student, developed a strong interest in this direction and unexpectedly continued his research for more than six years.
"One time, when I was on a bus passing by the Sanjiaxi Bridge spanning the Xiang River, the appearance of this bridge was very similar to the surface catalytic reaction curve we had previously plotted." At that moment, Liu Guangdong thought, "It's such a coincidence, but then I immediately had a new idea: even though the bridge and the curve are so similar, they are still completely different. Are there also no two identical reaction sites during catalytic reactions?"
Comparing the surface catalytic reaction curves developed by the San Gabriel Bridge team. Image provided by the interviewee.
In fact, this hypothesis has been previously explored by Deng Huiqiu's team, and what they are doing now is to experimentally verify this theoretical prediction.
Deng Huiqiu explained that through extensive research, they found that previous researchers observed catalytic reactions based on small systems and models, often only seeing local situations or a general framework, and couldn't observe significant differences in activity.
Therefore, with the support of computational resources from the National Supercomputing Changsha Center at Hunan University and the Advanced Computing Rosen Center at Purdue University in the United States, the research team calculated the surface stress and strain of stepped surfaces with widths ranging from 1 nanometer to 10 nanometers. They found that step-like defects can release enormous surface stress, driving atomic relaxation across non-uniform strain fields spanning several nanometers in width. The compressive strain can reach up to 5.5%, leading to different electronic structures and reactivity of platform surface atoms with the same local coordination, thereby enhancing the specificity of electrochemical oxygen reduction reaction activity.
"Ten nanometers is actually very small, but in theoretical models, it's quite large. It's like a 'super magnifying glass' that allows us to see catalytic reactions more clearly," said Deng Huiqiu, noting that previous studies on small systems and models couldn't observe differences in active sites. The team continually widened and enlarged the system, and through a series of studies, they discovered that the catalytic activity of each site was different, with the electrochemical oxygen reduction reaction activity of atoms on both sides of a stepped surface edge being 50 times higher than those in the middle of the platform.
It took the team over five years from proposing the theoretical prediction to experimentally verifying it. Deng Huiqiu said that their research explains the fundamental reason for the significant errors in predicting catalytic activity using the classical discrete active site model, unraveling the mystery surrounding the sensitivity of active sites and oxygen reduction reaction structures, and providing a new perspective for understanding catalytic activity sites and designing multiphase catalysts, making predictions and computational designs of multiphase catalysts more accurate.
Reviewers believe that this study fills a long-standing gap in the fundamental understanding of electrocatalysis, not only demonstrating the importance of surface strain variations but also providing a framework to map this behavior.
The trough period of not leaving the dormitory and not daring to see classmates
Liu Guangdong comes from a rural family in Hengyang, Hunan. "Typically, it takes about 5 to 6 years for a direct Ph.D. or Ph.D. program. I spent 3 years on my master's degree and another 4 years on my Ph.D. degree." Recalling the time two years ago when he was about to graduate with a Ph.D., Liu Guangdong had many feelings.
Scientific research is a process of continually posing and solving problems. From the second year of his master's degree to his Ph.D., Liu Guangdong gradually delved into research related to surface stress-driven reaction activity. However, critical results were not achieved until he graduated with his Ph.D.
"At that time, many classmates had published papers, and some had already graduated and found jobs, but I hadn't finalized my graduation thesis. There were three reviewers for the initial review. The opinions of the three reviewers were sent to the corresponding author together. One of the reviewers said, 'The paper can be accepted for publication in Nature without any modifications,' but the other two reviewers had different opinions, suggesting that the paper needed major revisions," Liu Guangdong said.
Academic pressure and some external factors made Liu Guangdong increasingly anxious. At that time, he had been in a long-distance relationship with his girlfriend for over 3 years, and both families were urging them to get married. As Liu Guangdong had not yet found a job, he had little savings. During that time, Liu Guangdong dared not leave the dormitory or see classmates. He spent his days in the dormitory busily writing his thesis, "not sleeping well, not eating well, with pimples on my face and sores in my mouth."
Although he briefly considered giving up, Liu Guangdong couldn't bear to abandon the research he had persisted in for so long.
Deng Huiqiu has a habit of going directly to the laboratory after work to understand what new problems students are encountering and what new demands they have, with the aim of not letting students linger on a difficult problem for too long. At one point, Deng Huiqiu noticed that Liu Guangdong hadn't been to the lab for several days, so he took him to the office for a heart-to-heart talk.
"We've all been through this. I deeply understand Guangdong's pressure. Even though our research group provides relatively high subsidies for master's and Ph.D. students, it's still a drop in the bucket for a young person who hasn't yet started working and wants to start a family and establish a career," Deng Huiqiu said, inviting Liu Guangdong out for meals and chats several times, gradually comforting him.
"I listed several life choices for him, including continuing research or directly graduating to become a teacher and educate others," Deng Huiqiu recalled. "But I also kept telling him that if you have dreams and pursuits, you must persevere, especially in scientific research."
Under the guidance of his teacher, Liu Guangdong calmed down and continued to immerse himself in research. This time, the paper was officially accepted and published in Nature, finally relieving Liu Guangdong. "Fortunately, I chose to persevere. Although the paper underwent three major revisions and spanned three years, I believe that persistence leads to victory." With the input from reviewers and the polishing by collaborators, this paper was revised over a hundred times, making the first version of the paper look completely different from the published version.
After graduating, Liu Guangdong stayed in his original research group to continue his postdoctoral research. Now, he has a new understanding of scientific research and ideas for future research directions. "If you're struggling with whether to do scientific research or which field of research to pursue, please do thorough research first. It's important to choose the right guide and platform."
"My Ph.D. students are willing to stay and continue as postdocs."
There is a phenomenon in the academic circle: many Ph.D. graduates choose not to continue their postdoctoral research in their original research groups but go to other universities or research institutions instead. Some people think that staying in the original group is like reading an extended version of a Ph.D., while others believe that from an academic perspective, moving to a new place may bring new perspectives and resources.
"My Ph.D. students are willing to stay and continue as postdocs," Deng Huiqiu said. Currently, his team has more than 50 members, including young faculty, postdocs, Ph.D. students, and master's students.
Deng Huiqiu (center) and some team members posing for a photo. Image provided by the interviewee.
When it comes to nurturing a research team, Deng Huiqiu has his own approach. Firstly, he fully supports students in conducting significant scientific research aligned with national needs.
"We support our students wholeheartedly as long as there is a valid need," Deng Huiqiu believes that each student has different interests and capabilities. Some students are suited for independent exploration, so Deng encourages them to pursue research based on their interests, providing guidance without imposing fixed research tasks. For other students, they work together to develop rigorous research plans and specific tasks. Liu Guangdong is one of the students who chooses to explore and research independently.
Deng Huiqiu reveals that the research results published this time did not have fixed research project support behind them. "The research lasted for several years, and funding was very tight. Our international collaborators provided strong support, exemplifying a win-win cooperation."
Once students have a certain research foundation, Deng actively recommends them to participate in domestic and international exchanges and collaborations. "This is actually a manifestation of strong collaboration. When I engage in collaborative exchanges, I don't seek quantity, but the collaborators must be stronger than us in certain aspects, so that students can learn in stronger teams, and both students and the entire team can progress faster."
"I'm already a veteran in scientific research; I want to leave more opportunities for young people," Deng Huiqiu told the China Science Daily. One of the corresponding authors of the published paper, Zeng Zhenhua, was his former master's student.
Deng Huiqiu has long demanded that the team "train the strong to lead the weak": "During their studies, I fully support students, and I hope that when they graduate and have better development and bigger platforms, they will come back to help younger students. This is also a form of giving back." Zeng Zhenhua is now a scholar at Purdue University, and this research was initiated through his proactive contact with the team.
"In such a virtuous cycle, more and more students like Zeng Zhenhua and Liu Guangdong are growing up, and we look forward to them achieving more new research results," Deng Huiqiu said.
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