A Conversation with Ib Chorkendorff

Abstract

Prof. Ib Chorkendorff is a Professor in the Department of Physics at Danmarks Tekniske Universitet (DTU). His initial research interest focused on surface reactivity of heterogeneous catalysts, and later expanded to include electrocatalysis and photoelectrocatalysis for energy harvesting and conversion. Notably, his seminal contributions to the fundamental understanding of CO₂ and N₂ reduction have led to new advances in designing electrocatalytic systems for sustainable fuels. He remains a leading advocate for reducing our carbon footprint through the development of sustainable fuels. The Department of Physics at DTU has been organizing a summer school for students and young researchers for the last two decades. (1) During my recent participation in the 2024 SurfCat Summer School (Figure 1), I had the opportunity to converse with Prof. Ib Chorkendorff. Figure 1. During a discussion with Ib Chorkendorff at the 2024 SurfCat Summer School, Kobaek Strand, Denmark. (Photo Courtesy: P. Kamat) PK: What were the early motivations that led you to get interested in electrocatalysis research? IC: From a young age, I was deeply interested in energy and energy conversion. This interest dates back to my high school days in the 1970s in Denmark, when car-free Sundays were introduced due to gasoline and oil shortages─an energy vulnerability that left a lasting impression on me. During my studies, I specialized in surface science, though without focusing specifically on energy, as the crisis had subsided for the time being. While working on my master’s degree, I had the opportunity to spend six months at Haldor Topsoe A/S, a Danish catalyst manufacturer. This experience helped me realize what I wanted to pursue as a career. After completing my Ph.D. in surface science of rare earth metals and their alloys, I did my postdoctoral work with John Yates at the University of Pittsburgh, where I earned experience on surface reactions and catalysis. In the early part of my career, I focused on single-crystal surface reactions and thermal catalysis, supported by collaborations with Haldor Topsoe, who encouraged more rigorous teaching of these subjects at DTU. By the turn of the century, I returned to my passion for energy, initiating a project called “Towards a Hydrogen Society”, where fuel cells were seen as an efficient energy source. Initially, electrochemistry held little appeal for me, as I associated it mainly with corrosion of automobiles and electroplating, both of which I found uninteresting. However, from an energy perspective, new possibilities opened up, and I began exploring fundamental single-crystal studies, fuel cells, and eventually photoelectrocatalysis. In recent years, my work has focused on energy conversion─particularly water splitting─and the challenge of coupling protons directly to CO₂ or N₂ to produce chemicals and fuels. My approach has generally been based on my background in surface science. I avoided battery research, since much of the activity in that field occurs at buried interfaces that are challenging to access with these methodologies. Nevertheless, I eventually ventured into that area as well, particularly in the context of ammonia synthesis, which involved a lithium-mediated process where complex solid–electrolyte interface (SEI) layers form. Although I found ways around this challenge, a deeper understanding of the SEI layer remains still desirable. Overall, my journey has been driven by the desire for energy self-sufficiency and a curiosity about the atomic-level processes underlying catalytic reactions. PK: What are the current grand challenges in electrocatalysis research? How does your Center strategize the efforts to address them? IC: The ultimate goal of our center is to eliminate greenhouse gas emissions, and the most straightforward way to achieve this is by entirely out-phasing fossil fuels. This approach should take priority over, for example, CO₂ sequestration for good, which I fear may serve as an excuse for oil companies to continue with “business as usual”. Achieving fossil-free energy is feasible since we have abundant solar and wind resources, even in a northern country like Denmark. Let’s electrify everything we can and then concentrate on finding solutions for what cannot be electrified. To manage energy sustainably, we’ll need to store it long-term in the form of chemical energy. We will also need to produce chemicals and fuels, the latter primarily for applications like long-haul shipping and aviation, where electrification is less viable. From an electrochemical perspective, this process begins with water splitting to produce hydrogen and oxygen─an essential step that, despite being established for centuries, still involves a ∼30% energy loss. Reducing this loss is crucial. While some argue that energy will be “free” in the future, this is unrealistic; people investing in solar panels and wind turbines will want a return. The negative prices for renewable energy are likely only during a transitional period where we need to create a market for energy conversion which is basically non-existing today. Hydrogen produced from water splitting can support well-established thermal catalysis for manufacturing chemicals and fuels from CO₂ and N₂. These processes may need to adapt, though, as energy becomes decentralized. For example, while ammonia production today relies on large facilities due to the capital-intensive Haber–Bosch process caused by its high operating pressure, it might make more sense to shift to a decentralized approach since both energy production and fertilizer use are very delocalized. The oxygen generated from water splitting will also be valuable, as it can support biomass combustion in power plants to stabilize intermittent renewable energy sources. This process will produce CO₂ at much higher concentration, which we can use as a feedstock for synthesizing organic chemicals and aviation fuel. So, in this context, CO₂ capture and storage is relevant. We are asking questions like, “Can we make the conventional processes more efficient or find entirely new routes for energy conversion?” It is naturally also important to ask if it makes any sense─often we see new approaches where simple energy efficiency calculation rules them out beforehand. We are currently focusing on electrochemical hydrogenation of both CO₂ and N₂ to create competitive alternatives to conventional thermal processes. Entirely new approaches like photoelectrocatalysis, which captures light energy and directly converts it into fuels or chemicals, remains an attractive concept that we also have pursued. However, we also recognized that it may not be viable within the time frame needed to address climate challenges, so we have reallocated more funding to ammonia synthesis, exploring both thermal and electrochemical approaches. Combining these two approaches may ultimately be the most effective option. This flexibility in funding allows us to make strategic adjustments as we gain new insights and progress. PK: Water electrolyzers have been commercialized for large-scale hydrogen generation. What other electrocatalysis-based technologies are likely to emerge in the near future? IC: In my opinion, good progress has been made in electrochemical CO₂. The field has managed to achieve reasonable current densities, though challenges remain with selectivity, stability and energy efficiency. I find N₂ hydrogenation particularly interesting, but it is further from the target, as the current density is still an order of magnitude too low, and energy efficiency needs improvements by a factor of at least 3–4. There are also some more localized solutions that are of interest: For example, we have made a spin-off company, HpNow, that focuses on electrochemical production of hydrogen peroxide. Such decentralized facilities could also be used to upgrade waste streams or for cleaning purposes. However, these applications are more aligned with niche industries rather than addressing the larger-scale challenges. PK: You have co-founded three companies based on the work carried out in your laboratory. What were some of the challenges you encountered in taking the laboratory work to the development of commercial products? IC: First, I’d like to point out that starting companies has often happened more by opportunity than by initial planning. Sometimes, you gain enough insight to see potential, and if Ph.D. students or postdocs are interested in pursuing it, starting a company becomes a possibility. In principle, it’s relatively easy to start a company; however, creating one that actually turns a profit, rather than simply burning through investments, is a completely different challenge. The current investment climate makes getting started feasible, but the real hurdle is scaling up to mass production. This stage requires much more capital, and it’s often where scientists lose influence and interest. Fortunately, there are others who thrive on this phase and enjoy managing those challenges. Of the three companies I’ve helped start, two are still healthy and active─HPNow and Spectroinlets─while the technology from the third company, RenCat, was recently bought out by Alfa Laval, which I also consider a success. There have also been other startups from our lab, though I’m not directly involved with them as I didn’t believe they were viable. PK: What is your advice to young researchers who aspire to engage in renewable energy research? IC: I would say to any young researcher aspiring to make science a career: stay curious and appreciate that, as a university professor, you have the freedom to choose your field of research─provided you can secure funding for it. Also, you will have great colleagues and meet many interesting and friendly people on your path. Of course, you should also enjoy teaching, as it’s an integral part of being a professor. There are also excellent opportunities in industry that can fulfill many of the same goals, though the degree of freedom is naturally not the same. Scientifically, renewable energy research presents many unanswered questions that are essential to solving our pressing global challenges. This field is appealing because it is easy to justify why this type of research is important and how it can contribute to a better world. However, the main driving force should still be curiosity, as that’s what propels research forward. You may not achieve your initial goal, but along the way, you might gain deeper insights that contribute to the field, paving the way for future breakthroughs by you or others. Research is far from a straightforward path from A to B. Sometimes, unexpected solutions emerge while trying to answer completely different questions or challenges. For this reason, it’s important to stay open-minded and opportunistic, looking beyond the immediate project. Finally, I would encourage the research community to be more rigorous in their approach. Too often, the focus is on the quantity of publications rather than the content and quality. Research quality could be significantly improved if we adhered to the “good old school” standards, where measurement uncertainties were carefully considered and reported. I always say, “seeing something once doesn’t mean you’ve truly seen it.” Ideally, I like to see results replicated three times to establish measurement reliability and give a standard deviation. Unfortunately, too often, observations are measured only once and cannot be reproduced. So, tighten up your ship, because, as Richard Feynman famously said, “The first principle is that you must not fool yourself, and you are the easiest person to fool.” With that, I wish you good luck out there. Nothing beats luck, but it usually only comes after hard work─and one must also be capable of recognizing it. Prof. Ib Chorkendorff is a Professor in the Department of Physics, Danmarks Tekniske Universitet (DTU), Kongens Lyngby, Denmark. He earned his Ph.D. degree in Physics at the Physics Institute, Odense University. In 1986–87, he was a postdoc with Prof. John Yates, Jr., at the University of Pittsburgh, USA. He then joined The Technical University of Denmark (DTU) as an Associate Professor in 1987, and in 1999 he was appointed full Professor in Heterogeneous Catalysis in the Department of Physics and Chemical Engineering at DTU. He was the director of the Center for Individual Nanoparticle Functionality (CINF) at Department of Physics, DTU, between 2005 and 2015. He later served as the director of the VILLUM Center for the Science of Sustainable Fuels and Chemicals (V-SUSTAIN) between 2016 and 2024. He has published over 450 scientific papers and co-founded three spin-off companies. Clarivate Analytics has recognized him as Highly Cited Researcher since 2017. He was awarded the Julius Thomsen Gold medal (2019), a Hans Fischer Fellowship at the Technical University of Munich (2020), the Villum Kann Rassmussen Annual Award (2021), and the Eni Award: Energy Frontiers Prize (2022). 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