In the quiet space between electrode and molecule, Seoul National University chemists discovered that the invisible chemistry of local acidity had been shaping—and often sabotaging—electrochemical reactions for decades without recognition. By learning to govern the microscopic pH environment rather than only the macroscopic conditions of voltage and solution, Jaeyune Ryu's team transformed a reaction that once yielded barely one useful molecule in six into one that yields nearly all of them. The work is a reminder that the most consequential variables are sometimes the ones closest to the acti
Controlling electrode acidity boosts plastic feedstock synthesis to 97% efficiency
The reaction's fate hinged on controlling the local environment.
Mark
So the researchers found that the acidity right next to the electrode matters more than the acidity of the whole solution. Why was this overlooked for so long?
Mimi
Because it's invisible to standard measurements. When you measure pH, you're measuring the bulk solution. The local environment at the electrode surface is microscopic and transient—protons are being generated or consumed faster than they can diffuse away, creating these extreme pockets of acidity or alkalinity. Nobody was really looking there until this team decided to.
Luke
But how confident are we that this is actually the mechanism? They're inferring local pH from electrochemical measurements and simulations. Did they directly measure it?
Mimi
They used electrochemical techniques to estimate it—pH 11 at the cathode, pH 2.5 at the anode. It's not a direct probe, but the evidence is strong: when they designed a reactor to counterbalance those extremes, selectivity jumped from 16 to 97 percent. That's not a small effect.
Mark
And the reactor design is just narrowing the gap between electrodes and letting solution flow through?
Mimi
Exactly. Tighter spacing and flow allow the acidic and alkaline zones to mix and moderate each other. When they stopped the flow entirely, almost no product formed, even with everything else held constant. The flow is essential.
Luke
That's a clean experiment. But I want to flag something: they tested this on one representative reaction—Baeyer-Villiger oxidation. They showed it works for lactones and epoxides, but that's still a limited set. The claim that this principle applies broadly to organic electrosynthesis is based on analyzing 600 papers, not on testing 600 reactions.
Mimi
Fair point. But the analysis of those 600 papers is revealing—89 percent involved proton transfer. That suggests the phenomenon is widespread, even if they haven't demonstrated the fix works everywhere.
Mark
What about scaling? Can this actually work in a factory?
Mimi
That's the open question. The researchers are explicit about it: they need further optimization and validation at production scale. Room temperature and atmospheric pressure are advantages—no special equipment needed. But moving from a lab reactor to industrial volumes is always a leap.
Luke
And the electricity source matters too. They mention potential coupling with renewable energy, but that's speculative. Right now, they're running it on whatever power is available. The sustainability story depends on where the electricity comes from.
Mark
So what's the real takeaway here?
Mimi
They've identified a design principle that was hiding in plain sight and shown it can dramatically improve a real synthesis. That's valuable. Whether it transforms the field depends on whether it scales and whether other reactions respond as well as this one did.
Le Pouls
- A mismatch between how fast protons are produced at electrodes and how slowly they diffuse away creates extreme local pH swings—pH 11 at the cathode, pH 2.5 at the anode—even in solutions that appear chemically neutral.
- A survey of over 600 electrochemical studies revealed that nearly 89 percent involved proton transfer alongside electron transfer, meaning this overlooked variable had been quietly distorting results across the field for years.
- The team engineered a reactor that narrows electrode spacing and circulates electrolyte flow, forcing acidic and alkaline microenvironments to counterbalance each other rather than independently wreck the reaction.
- Product selectivity leapt from 16 percent to 97 percent, and when electrolyte flow was stopped entirely, almost no target product formed at all—proving that local environment, not voltage, was the decisive factor.
- The method now synthesizes lactones and epoxides at room temperature without hazardous oxidants, with potential reach into pharmaceuticals and fine chemicals if the principle survives the journey from lab bench to industrial scale.
In the quiet space between electrode and molecule, Seoul National University chemists discovered that the invisible chemistry of local acidity had been shaping—and often sabotaging—electrochemical reactions for decades without recognition. By learning to govern the microscopic pH environment rather than only the macroscopic conditions of voltage and solution, Jaeyune Ryu's team transformed a reaction that once yielded barely one useful molecule in six into one that yields nearly all of them. The work is a reminder that the most consequential variables are sometimes the ones closest to the action, hidden not by complexity but by assumption.
A team at Seoul National University has identified something hiding in plain sight: the acidity immediately surrounding an electrode can make or break a chemical reaction. For years, researchers optimizing electrochemical synthesis focused on voltage, electrode material, and electrolyte composition while ignoring the microscopic environment where molecules actually exchange electrons. Jaeyune Ryu and his group discovered that this oversight was costing them efficiency—and found a way to fix it.
The problem begins with speed. When protons are generated or consumed at an electrode faster than they can diffuse away, local pH diverges sharply from the bulk solution. Even in nominally neutral conditions, the cathode region reached pH 11 while the anode region dropped to pH 2.5. These extremes alter which reactive species form, change the chemical state of starting materials, and accelerate product degradation. A review of over 600 papers on organic electrosynthesis found that roughly 89 percent involved proton transfer alongside electron transfer—suggesting the phenomenon was not a niche concern but a widespread, systematically overlooked variable.
To demonstrate the principle, the team targeted Baeyer-Villiger oxidation, a reaction that inserts an oxygen atom into a ketone to produce a lactone—a feedstock for biodegradable plastics and polyurethanes. Rather than relying on hazardous peroxyacids, they activated oxygen gas at the electrode and transferred it directly to the organic molecule. The two electrodes work in tandem: reactive oxygen species at the cathode initiate the transfer, while hydrogen peroxide produced in the process is recycled back into reactive species at the anode. The system is tightly coupled and highly sensitive to local pH.
The breakthrough came through reactor design. By narrowing the gap between electrodes and allowing electrolyte to flow between them, the team brought acidic and alkaline microenvironments into closer contact so they could counterbalance each other. Product selectivity jumped from roughly 16 percent to 97 percent. Reducing electrode spacing from 20 millimeters to 4 millimeters increased production rate by about 2.2-fold, and varying flow rate produced a 14-fold difference in output. When flow was stopped entirely, almost no target product formed—even with voltage and composition unchanged.
The team synthesized lactones from 18 different ketone compounds, achieving 82 percent yield of epsilon-caprolactone, a feedstock for the biodegradable polymer used in surgical sutures and drug-delivery systems. They applied the same principle to epoxide synthesis across six alkene substrates, producing key feedstocks for adhesives, coatings, and electronics resins. The entire process runs at room temperature and atmospheric pressure, with electricity as the sole energy input. Published in the Journal of the American Chemical Society, the findings reframe electrochemical design: not just optimizing voltage or solution, but engineering the actual environment where molecules react—a frontier with implications stretching well beyond this single reaction.
A team at Seoul National University has identified something that was hiding in plain sight: the acidity immediately surrounding an electrode can make or break a chemical reaction. For years, researchers optimizing electrochemical synthesis focused on the obvious variables—voltage, electrode material, electrolyte composition—while largely ignoring the microscopic environment where molecules actually exchange electrons. Jaeyune Ryu and his group discovered that this oversight was costing them efficiency, and they found a way to fix it.
The problem begins with a mismatch in speed. When protons are generated or consumed at an electrode faster than they can diffuse through the solution, the local pH diverges sharply from the bulk solution's pH. In their experiments, even when the overall solution was nominally neutral, the region near the cathode became alkaline—reaching pH 11—while the area near the anode turned acidic, dropping to pH 2.5. These extreme local conditions alter which reactive oxygen species form, change the chemical state of starting materials, and accelerate product degradation. The researchers analyzed over 600 papers on organic electrosynthesis published since 2010 and found that in roughly 89 percent of them, reactions involved proton transfer alongside electron transfer. This suggested the phenomenon was not a niche concern but a widespread variable that had been systematically overlooked.
To demonstrate the principle, the team focused on Baeyer-Villiger oxidation, a reaction that inserts an oxygen atom into a ketone to produce an ester or lactone. Lactones matter because they serve as feedstocks for biodegradable plastics and polyurethanes—materials in everyday use. Conventional synthesis relies on highly reactive peroxyacids, which are hazardous to handle and generate problematic byproducts. The researchers instead activated oxygen gas at the electrode and transferred the oxygen atom directly to the organic molecule. Isotope tracing confirmed the oxygen came from gas, not water. They also mapped how the two electrodes work together: reactive oxygen species generated at the cathode initiate the oxygen-transfer reaction, while hydrogen peroxide produced in the process gets recycled back into reactive species at the anode. The system is tightly coupled and highly sensitive to local pH.
The breakthrough came through reactor design. Working from computer simulations and electrochemical measurements, Ryu's team built a reactor that narrows the gap between electrodes and allows electrolyte to flow between them. The logic is straightforward: by bringing the acidic anode environment and alkaline cathode environment into closer contact, they counterbalance each other's extremes. When they tested this design, varying electrode spacing and flow rates, the results were dramatic. Product selectivity—the proportion of desired product formed—jumped from approximately 16 percent to 97 percent. Reducing electrode spacing from 20 millimeters to 4 millimeters increased production rate by roughly 2.2-fold. Increasing electrolyte flow rate produced a 14-fold difference in output between the slowest and fastest conditions tested. Most tellingly, when the solution was not allowed to flow at all, almost no target product formed, even though voltage and composition stayed identical. The reaction's fate hinged on controlling the local environment.
The team synthesized lactones from 18 different ketone compounds, achieving an 82 percent yield of epsilon-caprolactone, a feedstock for polycaprolactone—a biodegradable polymer used in surgical sutures and drug-delivery systems. They applied the same local pH control principle to epoxide synthesis, producing compounds from six alkene substrates. Epoxides are key feedstocks for adhesives, coatings, and epoxy resins in electronics. The entire process operates at room temperature and atmospheric pressure, requiring no separate heating or pressurization equipment. Because electricity is the energy source, the approach could eventually couple with renewable power generation.
The significance extends beyond this single reaction. Ryu's team has reframed how electrochemists should think about their work: not just optimizing voltage or solution composition, but designing the actual environment where molecules react. The findings were published in the Journal of the American Chemical Society. From an industrial standpoint, pharmaceutical and fine-chemical intermediates are natural candidates for this approach—they have high value and demand careful safety management, which aligns with electrochemical processes that reduce reliance on hazardous oxidants and require compact equipment. However, scaling from laboratory demonstration to commercial production remains ahead. The researchers acknowledge that further optimization and validation at production scale will be necessary before this becomes a manufacturing reality. The principle, though, opens a new design frontier: considering local pH in other electrosynthetic reactions involving proton transfer could reveal opportunities for improving efficiency and selectivity across the field.
Citations marquantes
This study transforms 'local pH' near the electrode from a hidden variable into a controllable design principle. To improve the efficiency of organic electrosynthesis, we need to design not only the reaction substrates and catalysts but also the environment in which the molecules actually react.— Jaeyune Ryu, Seoul National University
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