Drexel Materials Professor Yury Gogotsi, PhD, whose research as founder and director of the A.J. Drexel Nanomaterials Institute and member of the Department of Materials Science and Engineering has opened new possibilities for the application of nanomaterials, has received an h-index value of 100 from Google Scholar and other citation databases—the highest ever received by a professor within the College of Engineering.* The h-index classifies scholars according to the number of extant papers that have been cited by other scientists and publications. The Google Scholar distinction refers to Gogotsi’s papers published just since 2013.
A high h-index value signifies leadership in the field and underscores the degree to which an individual’s research has advanced and inspired the work of peer scientists. In Gogotsi’s case, the h value means he has 100 papers that have each received citations 100 times, an extraordinary level of influence.
Professor Yury Gogotsi
The h-index was developed by physicist Jorge Hirsch at the University of Southern California 13 years ago as a tool for assessing the impact of theoretical physicists’ research, and was adopted as a rating tool by citation databases like Google Scholar, Web of Science and Scopus. A value of 20 is considered laudable for a scientist with 20 years of research; 40 is outstanding; 60 is exceptional.
Together with Michel Barsoum, distinguished professor of Materials Science and Engineering, Gogotsi discovered the family of two-dimensional materials known as MXenes. MXenes have been hailed as “game-changing” materials for use in energy storage, optical data transmission, and electronic applications, among many other potential uses. Today, MXenes are studied at Drexel and throughout the world.
Gogotsi’s research also covers areas such as nanostructured materials for energy storage, biomedical applications, and filtration; nano- and micro-scale devices for electronics, and more.
Gogotsi has been with Drexel’s College of Engineering since 2000. He is Distinguished University and Charles T. and Ruth M. Bach Professor of Materials Science and Engineering.
Congratulations on your achievement, Dr. Gogotsi. Tell us why a researcher’s h-index is significant
It’s simply the number of papers that have been cited more than that number. It means I’ve published 100 papers that have been cited at least 100 times. Many consider it to be a really big number because there are just a couple of people in the world who get to 200. Someone who consistently publishes work makes an impact, so that other scientists cite the research in their own work. If I write a great paper and no one cares or cites it, it means that my paper didn’t really make a difference.
I personally think it’s an important metric. But as with any metrics, I don’t consider it to be the only one. In some fields, as in medicine, there are lots of researchers working in the field, lots of journals and lots of citations, and people cite many, many papers in every publication. So, people in that field have very high h-index values. And then in mathematics, people publish relatively few papers and cite relatively few, so the h-index values will be lower.
Web of Science has something called Hot Papers and Highly Cited papers. Hot Papers recognize the top .1 percent of the most-cited papers in the field in the past three years, which means it is adjusted to the field. It basically says, of 1,000 papers in our field, these are cited higher. So, it gives a better characterization, maybe, of how good the College of Engineering’s A.J. Drexel Nanomaterials Institute is in our field. We currently have eight papers which are in the .1%. And we have 66 Highly Cited papers that are in the top 1% in our field. So, what it means is that we consistently produce good results.
What does this distinction mean to you, personally?
It means that what we do matters. If people cite our paper 10,000 times, it means we have done something really important. So, it’s a kind of model reward for all of these efforts. Producing the research results and producing papers requires a lot of work. In the case of writing papers that really tell where the field should be, this demonstrates that we are also thought leaders in the field. This is something Drexel can be proud of because it means people all over the world follow ideas that come from CoE and follow the paths we’ve outlined.
So, in the case of MXenes, they were discovered at Drexel. But now there are about 300 research organizations already publishing on them, and I’m sure probably twice that number are working on MXenes in more than 40 countries around the world. I think this is something that’s very important for a research university—it means we make an impact worldwide. People in Australia or China or South Africa learn about Drexel by reading research papers.
Have you ever had students tell you that is why they’re here at the college of engineering?
Actually, most PhD students who come to Drexel to work with us come because of our research. This is how they select the place to study. They look for topical areas, they look for programs that are strong, and they look for professors because PhD study is such an individual matter—it’s a PhD student and an advisor. PhD students take classes for the first year, yes, but this is a minor part of their study. In a strong research group, they learn from their professors. They learn from their peers and post-docs (more senior group members).
What do you look for in team members?
I look for dedication. People come with many different backgrounds, and some are stronger, some are weaker. We have in my group people with backgrounds in physics, chemistry, mechanical, chemical, materials, and biomedical engineering. The key is really motivation and an interest to learn, to be the best in the world in their field, to do research. Those are the key parameters.
I always interview people. Moreover, I don’t rely just on myself. Whoever we invite as a post-doctoral researcher or even as an undergrad, my team always interviews them and I listen to their opinion. First, because they’re very smart people and they are in a closer age group, so it’s easier for them to evaluate who is really good. Second, whoever joins our group becomes a team member; there is no individual research. They will interact with each other so there must be chemistry. They must be willing to work with each other and collaborate. We try to make that decision collectively. If I like a potential candidate and my group says, no, we like someone else, I go with their decision.
What impact do highly cited papers have on students?
So, these things are really inspiring to students whenever they see results, see their papers published, see other scientists cite their work, and go to conferences and see the top scientists in the field—the “gods”—come and say, you’ve done such a good job.
As a university, our main products are not papers, but people. These are highly trained researchers who can do research that few other people in the world can do. They have learned how to do it here at the College of Engineering, and wherever they go they are going to be successful. I am most proud to see my former students now in professor positions or top industrial positions and publishing great papers in the best and most prestigious journals because they got their start at Drexel.
Age-old question: how do you find time to write and publish?
If you look at most of our papers, the majority of them are co-authored by a large group of people—five, 10, sometimes more scientists, and some of them often come from research groups outside Drexel. This is a trend of our time. The most exciting and most important problems facing us now are multidisciplinary problems. It’s not something in engineering and science that a single PhD student with his or her advisor can tackle; maybe 40 years ago that was the norm, but not now.
I alone am not writing a paper. We have 10 people maybe who contribute. We get together. We discuss an idea. My job as a professor, as a team leader, is to generate ideas and guide students. Students do research, collaborate with other people, write; I get the manuscript, I edit it, and sometimes it goes through 10 to 20 revisions. I do read, edit, and write every day. As you walked into my office, I was editing a paper of one of my master’s students who just graduated. On the train to Drexel this morning, I was reading another paper from another student. So, it means we’re constantly working on papers.
Do you see multidisciplinary work as essential to advancing technologies today?
It is essential now. We all work together. We are making materials here. But someone does the characterization. Someone else does the modeling and simulation. Someone else makes the device. So, it means that a lot of types of people are involved. This is something that really leads to acceleration of scientific and technological progress. If we are all isolated working on a problem, then there is a longer wait to application.
What do you look for when forming a research team?
We look for a couple of things. One is complementing expertise—people who can do something we cannot. Second is excellence—we want to work with people who are world-class scientists, who are equally dedicated, who love science and who want to make a difference. And if this comes together, those are our collaborators who can do groundbreaking, cutting-edge research and add something to our expertise.
Do most of your cited papers focus on MXenes?
In the past few years, yes. But if you look at these papers, you will actually find that the most cited paper I have—and actually it has more than 8,000 citations in Web of Science—this paper was actually something quite different from what I was discussing here. This was a review article, “Materials for electrochemical capacitors,” written by myself and my French collaborator, Professor Patrice Simon, from Paul Sabatier University in Toulouse, France, in 2008. This paper really defined the entire field of materials for capacitive energy storage and outlined directions for research. So, since it was published exactly 10 years ago, almost everyone working on electrochemical capacitors has been citing this work. It’s receiving about 1,500 citations per year.
Is that unusual, to have it cited so many years after publication?
No, it happens because it’s defining. There are some papers that really define the field, that tell thousands of people what to do, what are the directions, what is the state of the art, and where to go from there.
I’m sure the first paper where we reported the discovery of MXenes with my Drexel colleague Professor Michel W. Barsoum and our students and post-docs will also be cited for many years because, again, this is a first paper. So those types of publications have a very long lifetime.
Some of the publications are cited for a number of years and then go to zero because there is nothing else going on in the field. I have papers that I published when I was a PhD student working on structural ceramics. Hardly anyone is working on that topic now. People don’t cite them any longer. They have done their job and are no longer so important.
Do you have a favorite paper?
I have several papers I like that have not been cited that much. Those were papers coming from the most difficult experiments, from the most difficult studies. They get moderate citations. And one of the reasons is that it is so difficult for other groups to follow up on the research.
I can tell you for an example that I am very proud of the paper we worked on with other professors from Drexel, Dr. Gary Friedman from the Department of Electrical and Computer Engineering, and also colleagues from the College of Medicine, about making nanopipettes that can poke single cells; moreover, individual organelles in single cells. So basically, imagine a nano-syringe with a needle being about 100 nanometers. A human hair is about roughly 100 micrometers, so this would be a thousand times thinner than the human hair. I’m very proud of this work because I know how difficult it was and how much effort it took with excellent students and excellent postdocs. It was probably building on close to 10 years of research efforts dedicated to studying liquids in carbon nanotubes to generate this paper. It was some really beautiful work.
How important is publishing to scholarly impact?
There have been a number of studies showing that research productivity—the number of high-quality papers—is the only really universal indicator of success in everything else; in the total number of applications, quality of students, jobs people get, growth in university ranking. If you take one criterion, the number of publications and the quality of the publications is really the number one factor. Everything else comes after that. This is the single biggest indicator of productivity and success.
What is your advice to others regarding publishing?
It is still more important to have quality than quantity. Don’t try to publish too much. It will come by itself if the quality is there because other people will want to work with you. Do quality research and do your best to write high quality, high-impact publications. Because if you do great work and no one knows about it, there is no way to rate this work. Publications basically show the entire world, ‘This is what we have done.’
Other top institutions evaluate junior professors and give them tenure based on, first of all—not the number of grants received or the dollar amount, but if you become a leader in your field. And that is based on quality papers. If your work is in great journals, and you get highly cited, you deserve to get tenure.
*Drexel researchers were unable to locate other faculty members with an h-index value over 100, and believe that Gogotsi’s distinction is the first. However, different citation databases use different means to calculate h-index values, so the h value can fluctuate depending on those means.
Elizabeth Ten Have, Director, Library Academic Partnerships/Drexel University Libraries contributed information to this article.