Renewable Energy

Proton-Coupled Energy Transfer Deciphered: High-Pressure Research Reveals Key Mechanisms

Science, Technology / By

In a groundbreaking study, a team of researchers have discovered new mechanisms of proton-coupled electron transfer (PCET), a fundamental process that is the base for life-sustaining reactions such as cellular respiration and photosynthesis. Using an innovative high-pressure technique, the team has successfully distinguished between two key reaction mechanisms, paving the way for advancements in energy conversion and storage technologies.

The Balancing Act of Electrons and Protons

Redox reactions, which involve the transfer of electrons between molecules, are critical to both natural and industrial processes. However, electron transfer alone can create energetically unfavorable charge imbalances. Nature’s solution? Coupling electron transfer with the movement of positively charged protons. As the researchers explain, “This proton-coupled electron transfer (PCET), as it is known, does not produce any change in charge—the most efficient way for a redox reaction to occur.”

But how exactly do these transfers occur? There are two possibilities: either electrons and protons move simultaneously in a “concerted” mechanism, or they transfer separately in a stepwise fashion. “To be able to optimize these processes, we need to know the exact mechanisms,” says Professor Ivana Ivanović-Burmazović. “Before now, however, there has been no direct method for differentiating the two alternatives with certainty. Our work set out to remedy this.”

Pressure Yields the Answer

The research team, led by Professor Ivana Ivanović-Burmazović of LMU Munich and Professor Dirk Guldi from FAU Erlangen-Nürnberg, investigated the influence of pressure on a light-induced reaction in a photosensitive molecule. By applying pressures of up to 1,200 atmospheres (atm), they observed how the reaction rate changed or was unaffected under extreme conditions. “If high pressure—in the experiment, up to 1,200 atmospheres—is applied and the reaction rate remains unchanged, it is a concerted reaction,” explains Ivanović-Burmazović. “When electrons and protons are transferred simultaneously, charge of reacting species does not change and neither does the associated solvation sphere—that is, the cluster of solvent molecules surrounding the molecules. Therefore, pressure has no influence on reaction rate—a clear sign of a concerted mechanism.” Conversely, if the rate changes, this points to changes in the charge and to a change in the volume of the solvation sphere—indicating a stepwise process.

Original diagram explaining (pressure-based) Concerted vs Stepwise mechanisms

Surprising Control Over Reaction Pathways

The team’s findings went beyond mere observation. “By increasing the pressure, we managed to steer the reaction from a stepwise mechanism toward a concerted mechanism,” says Ivanović-Burmazović. This level of control opens up new possibilities for designing and optimizing chemical processes.

Implications for Energy and Beyond

The study’s results have potential for practical applications. As the authors emphasize, “The new findings are highly significant for numerous research areas that deal with the motion of electrons and protons. They not only offer new insights into fundamental chemical processes, but could also help advance new technologies concerned with the conversion and storage of chemical energy—such as redox catalysis for the generation of solar fuels or for hydrogen production.”

Example of high-pressure reactors (Optimus Instruments)

Looking Ahead

The team’s innovative use of high-pressure techniques sets a new standard for studying complex reaction mechanisms. As researchers continue to explore the intricacies of PCET, the findings could lead to breakthroughs in fields as diverse as biochemistry, materials science, and renewable energy.

For now, one thing is clear: the connection between high-pressure science and molecular chemistry has furthered our understanding of the building blocks of life and energy to a new level.

Citations:

Langford, D., Rohr, R., Bauroth, S. et al. High-pressure pump–probe experiments reveal the mechanism of excited-state proton-coupled electron transfer and a shift from stepwise to concerted pathways. Nat. Chem. (2025). https://doi.org/10.1038/s41557-025-01772-5

Ludwig-Maximilians-Universität München. “Proton-coupled electron transfer: Deciphered with high pressure.” ScienceDaily. ScienceDaily, 21 March 2025. <www.sciencedaily.com/releases/2025/03/250321121450.htm>.

High pressure reactors – optimus instruments. (2024, June 27). Optimus Instruments. https://optimus.be/subject/high-pressure-reactors/

Stopping the Energy Crisis Clock?

Engineering, Technology / By

Less than 120 years. That’s the duration in which all nonrenewable energy will be fully exhausted. Although that sounds like a long time away, a whole lifetime away, in fact, this is a problem that needs to be addressed. 

Part of the reason as to why this issue needs to be solved is because of the exponential growth of fossil fuel usage. Compared to 1950, approximately 70 years ago from the date of this article, gas consumption has risen nearly twenty times as much, a staggering increase. 

Image Credit: https://ourworldindata.org/fossil-fuels, depiction fossil fuel consumption rates over the years.

It’s not unrealistic to say that, as time progresses, consumption of fossil fuels will continue to rise and thus, reduce their supply and hasten their end.

Thankfully, people have been paying attention to this issue (dubbed the energy crisis). Many have even made adjustments in varying degrees, from installing solar panels and foregoing nonrenewable resources (a relatively minor contribution) to proposing bills such as the Green New Deal, which would implement a gradual nationwide swap into renewable resources (a massive commitment). These are just two examples of how humans have been attempting to solve this problem.

Unfortunately, many of these potential methods have posed their innate issues. When it comes to adopting renewable energy resources, they either run the risk of being too costly (such as hydroelectric and solar) or unreliable (such as wind and solar), which are only available around 30% of the time. 

In addition, there has been extreme pushback against any means to delay (if not outright prevent) the energy crisis when it comes to large legislation such as the Green New Deal, with some citing that it’s too expensive (with a $93 trillion, twelve zeroes worth, price tag) and will submerge the U.S. into debt they can never get out of. With all the energy crisis efforts, both large and tiny, being fought against, it begs the question of whether there is any sort of renewable energy that can check all (or even most) of the boxes that would make everyone happy. 

That question was answered positively at the end of 2022. Beyond beckoning a new year, December also welcomed a new (or rather, improved) renewable energy source: nuclear energy. For the first time since the history of its experimentation, nuclear fusion/fission (the process of achieving nuclear energy) had reached a net gain, producing more energy than what it receives.

This discovery checked many boxes at first: it was reliable (with nuclear fuel being abundant in the environment) and exceptionally efficient, with a single gram of uranium being able to produce as much energy as a ton, 2,000 pounds that is, of coal. It also is a clean source of energy, an award that non-renewable energy fails to achieve. 

However, like all the benefits of discovery, there are bound to be drawbacks, and this was no exception. The first major issue is the extremely advanced technological nature of fusion: it makes it tough to master and replicate easily. The second vice ties into the first perfectly, with it being simply too expensive to sustain due to the immense amount of energy needed. Finally, the stereotypical reason why people fear nuclear energy: the danger. Although this stereotype is grossly exaggerated, there is some truth to the matter. Both malfunctioning accidents (like Chernobyl and Fukushima) and long-term radioactive waste that must be stored securely are issues that just cannot be ignored. 

Although nuclear energy does have some (rather large) issues, it’s important to not forget about its boons as well. From its efficient nature to being reliable and clean simultaneously, fusion is not a renewable energy source to underestimate. Regardless of what side you are on, nuclear energy brings up an important thing to think about: imagine what could be possible over the next century when it comes to technological innovation?

  1. https://group.met.com/en/mind-the-fyouture/mindthefyouture/when-will-fossil-fuels-run-out
  2. https://ourworldindata.org/fossil-fuels
  3. https://www.forbes.com/sites/judeclemente/2019/04/29/five-practical-problems-for-the-green-new-deal/?sh=5892345f3e8a
  4. https://stacker.com/science/22-biggest-scientific-discoveries-2022