Cleaning up clean energy

University of Delaware researchers develop a green recycling process that recovers valuable metals from fuel cells and other hydrogen technologies.

University of Delaware

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The future hydrogen economy may hinge on iridium, a metal so rare that only about eight tons are produced worldwide each year. To help stretch the limited supply, University of Delaware researchers have developed a recycling process that recovers precious metals and other materials from used hydrogen-energy devices without producing toxic waste.

Among the technologies driving hydrogen energy are proton exchange membrane (PEM) electrolyzers and fuel cells, which rely on catalysts made from iridium and platinum to produce and use hydrogen efficiently. PEM electrolyzers use electricity to split water into hydrogen and oxygen, while PEM fuel cells release stored energy by converting hydrogen back into electricity.

Platinum and especially iridium are difficult to obtain, expensive and in high demand. To recover these catalysts from used membranes, Safina-E-Tahura Siddiqui, a doctoral candidate in mechanical engineering working under the supervision of Ajay Prasad, developed a spray-jet method that enables recycling of both the precious-metal catalysts and the membrane itself. 

“It’s like pressure washing the siding of your house. You just sweep across the surface and remove the catalyst material,” explained Prasad, Engineering Alumni Distinguished Professor of Mechanical Engineering and associate director of the Center for Clean Hydrogen. 

Their approach, reported in the International Journal of Hydrogen Energy, is now being advanced toward commercialization through UD’s Office of Economic Innovations and Partnerships.

Addressing a critical bottleneck

Recycling becomes more important as demand for PEM technologies grows. Platinum is typically found in very low concentrations in mined ore, while iridium is not mined as a primary material and is recovered only as a byproduct of platinum mining.

“Iridium is the major bottleneck in PEM electrolyzers because of this,” Siddiqui said. “That is why we are focusing on recycling them from spent electrolyzers instead of depending on mining or market supply.”

While recycling catalysts from used PEM electrolyzers and fuel cells is not a new idea, existing methods come with environmental drawbacks. Some rely on harsh chemicals such as sulfuric and nitric acid, which generate toxic waste streams. Others involve burning the membrane to produce ash containing platinum and iridium, a process that can release fluorine-containing emissions.

In contrast, Siddiqui’s approach uses a controlled spray of isopropyl alcohol and water to detach the precious metals from the membrane.

“It is a green recycling method that uses no harsh chemicals and no burning,” said Prasad.

Recovering more than precious metals

Unlike other recycling approaches that focus solely on recovering metals, the UD method preserves the membrane itself, while also extracting platinum and iridium separately.

The industry-standard membranes used in PEM electrolyzers and fuel cells account for 20 to 30% of the cost of the stack, the central assembly where the electrochemical reactions occur. These membranes are made of polymers classified as PFAS, “forever chemicals” that persist in the environment for decades and contribute to contamination concerns.

The catalyst-coated membrane contains platinum and iridium catalyst layers on opposite sides. The UD researchers’ approach removes each layer sequentially, preserving the membrane while keeping the recovered platinum and iridium separate. If the metals mix during recycling, separating them becomes much more difficult.

Fine-tuning the technique

Though the principle behind the new recycling method is straightforward, the process requires careful control of jet velocity, solvent ratio, distance and temperature.

Siddiqui began with small-scale beaker tests, immersing tiny pieces of catalyst-coated membrane in solvent, heating them and timing how quickly the catalyst detached. She then conducted hundreds of experiments with membranes roughly the size of a postage stamp, varying temperature, solvent ratio and exposure time to determine optimal conditions.

One challenge emerged when the membrane interacted with the solvent. In some cases, it swelled to nearly twice its original size, causing it to sag and tear during jetting.

To overcome this problem, Siddiqui developed a heated vacuum bed that held the membrane flat while the catalyst layers were removed from each side.

Preparing materials for reuse

The researchers’ goals extend beyond recovering materials. In the next phase of the work, they will quantify recovery yields, characterize the recovered catalysts and membranes and test their performance in operating electrochemical cells.

Ultimately, they hope recovered catalysts and membranes will be reintroduced into new hydrogen-energy devices, helping create a more sustainable and resilient supply chain for technologies critical to the clean-energy transition.

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Journal

International Journal of Hydrogen Energy

DOI

10.1016/j.ijhydene.2026.154430 

Article Title

Green recycling of precious metal catalysts and membranes from PEM electrolyzers and fuel cells using a spray-jet system

 

DZIF project nominated for the “Science Breakthrough of the Year 2026” award

Falling Walls Foundation honors DZIF-supported research on novel antibiotics

German Center for Infection Research

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The project “PROTON—Breaking the Wall of Deadly Bacterial Infections”, led by Prof. Mark Brönstrup and significantly supported by the German Center for Infection Research (DZIF), has been nominated by the Falling Walls Foundation for the title “Science Breakthrough of the Year 2026” in the Life Sciences category. 

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Credit: Falling Walls Science Summit, HZI/Verena Meier

The project “PROTON—Breaking the Wall of Deadly Bacterial Infections” has been nominated by the Falling Walls Foundation for the title “Science Breakthrough of the Year 2026” in the Life Sciences category. The prestigious award honors scientific advances that break down barriers in science and have the potential to make a global impact.

The project, led by DZIF scientist Prof. Mark Brönstrup at the Helmholtz Centre for Infection Research (HZI), was nominated for the development of an innovative agent against the bacterial pathogen Staphylococcus aureus. As part of the project, which is substantially supported by the German Center for Infection Research (DZIF) and its Product Development Unit, the research team is developing novel active agents designed to significantly reduce the risk of antibiotic resistance.

The active agent belongs to a class of compounds known as “pathoblockers”. Unlike classic antibiotics, pathoblockers do not inhibit bacterial growth but instead specifically block the mechanisms that cause disease. The focus is on neutralizing a toxin produced by S. aureus that destroys lung tissue and immune cells. In the future, the product is intended to be used primarily for the prevention and treatment of pneumonia in in high-risk patients in hospitals.

The nomination highlights the potential of the “PROTON—Breaking the Wall of Deadly Bacterial Infections” project to translate excellent basic research into tangible medical innovations. The winners of the “Science Breakthrough of the Year 2026” awards will be announced at the Falling Walls Science Summit in Berlin this November.

Source: Press release of the Helmholtz Centre for Infection Research (HZI)

For more information on the “PROTON—Breaking the Wall of Deadly Bacterial Infections” project, please visit the DZIF website titled "Small-molecule inhibitors of Staphylococcus aureus alpha-toxin for severe lung infections".

 

Is hookah safer? Or is that belief just blowing smoke?

Researchers will examine how hookah size and heating methods affect exposure to toxins

University of Texas at Arlington

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Ziyad Ben Taleb, UT Arlington director of the Nicotine and Tobacco Research Laboratory

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Credit: Herschel Heath/ UT Arlington

Hookah is often seen as a cleaner alternative to smoking cigarettes, but researchers at The University of Texas at Arlington are launching a new study to put that assumption to the test.

Ziyad Ben Taleb, associate professor of kinesiology and director of the Nicotine and Tobacco Research Laboratory, has received a two-year, $442,763 grant from the National Institute on Drug Abuse to investigate how waterpipe size and heating sources affect hookah smoking.

“There is a new trend of electronic heating elements that heat the tobacco without combustion,” Dr. Ben Taleb said. “There are marketing claims that these are safer, but we don’t know. That’s why this study is needed.”

The study will involve 60 established hookah smokers who will use both large and small waterpipes and both traditional charcoal and newer electronic heating devices in separate sessions.

Hookah smoking is “highly prevalent and has been rising in popularity among young people worldwide,” according to a 2025 study. A typical hookah session lasts about 45 minutes and can expose users to more than 30 times as much carbon monoxide as a single cigarette. This prolonged exposure translates into a significant amount of smoke entering the body.

“In our previous studies, hookah users inhaled nearly 100 liters of smoke per session on average, while some single puffs exceeded two or three liters,” Ben Taleb said. “There is a misconception that hookah is safer because the smoke passes through water. In reality, the water cools the smoke, but it does not filter it.”

Ben Taleb hopes the findings will help people make informed decisions about hookah use. The research could also help guide future regulations by the U.S. Food and Drug Administration.

“My responsibility as a researcher is to empower people with evidence so they can make informed decisions about their health,” Ben Taleb said. “Also, agencies like the FDA need data on how different product configurations affect exposure, addiction and health. If we find that certain designs or heating methods increase risk, that information can help guide future public health policies.”

The study began on May 1 and will run through April 30, 2028.

 

Newly discovered corn trait may help improve crop drought tolerance

Researchers report some corn plants have longer cells and deeper roots that enable higher water absorption, potentially offering a target for breeding more resilient crops

Penn State

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Study first author Christopher Strock (right) leading collection of corn samples in the field at the research site in Chile, which were transported to field tents for sample preparation and processing. Corn for the study also was grown at Penn State's Russell E. Larson Agricultural Research Center. 

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Credit: Christopher Strock/Penn State

UNIVERSITY PARK, Pa. — Some corn plants are genetically predisposed to develop longer, less constricted water-conducting tissues and deeper roots, which helps them deal with drought. That’s the conclusion of a team led by Penn State researchers that conducted a study of the plant’s xylem tissue that moves water upward from the roots out to the leaves.

The researchers, who focused on metaxylem vessel element length — the length of the individual tube-like cells inside the xylem — recently published their findings in Crop Science. They found that corn plants with longer metaxylem vessel elements also tend to have rapidly elongating roots, deeper root systems, stronger water transport capacity, greater water capture and improved drought adaptation. These traits form a connected syndrome the team called the “stretch phenotype.”

“Drought is a primary limitation for crop production and is projected to worsen due to climate change,” said study senior author Jonathan Lynch, distinguished professor of plant nutrition in the Penn State College of Agricultural Sciences. “Understanding and managing crop drought tolerance is an urgent priority for global agriculture. This study shows that corn plants with longer xylem vessel elements move water more efficiently, grow deeper roots, access deeper soil moisture and produce better yields during drought.”

Corn plants naturally vary in metaxylem vessel element length, the researchers found. They analyzed hundreds of corn plants from different genetic lines, from different regions, with varying characteristics and found that some had the longer cells in their xylem; others had shorter cells.

The team reported that longer xylem vessel elements were associated with lower perforation plate height — meaning that there was less constriction where those cells grew together, making longer continuous vessels and better hydraulic conductance — a measure of how easily water moves through the tissue or root. A xylem perforation plate is the porous end wall connecting two adjacent vessel elements in a plant's vascular tissue. By dissolving these end walls during cell maturation, plants create continuous, open tubes that allow water and minerals to flow efficiently from the roots to the leaves.

“Think of it like this — short pipes with many barriers result in slower flow and conversely, long, smooth pipes conduct faster flow,” Lynch explained. “The perforation plates are like tiny partitions between xylem cells. Smaller/lower barriers mean less resistance to water flow. So, longer xylem vessel elements create a more efficient water-transport system.”

Perhaps more importantly, Lynch said, the stretch phenotype consists of longer cells in various pant tissues, including the roots, meaning that roots grow faster and reach deeper in the soil, which helps them acquire water under drought conditions.

The researchers used computer simulations to confirm the stretch phenotype by modeling how xylem traits affect water flow. They then checked real root tissue in corn they grew under drought stress in the greenhouse and at two field locations — one at Penn State’s Russell E. Larson Experimental Farm in central Pennsylvania and the other at the Tuniche Research Farm near Graneros, Chile. The team employed rain-exclusion structures to simulate drought conditions at the Pennsylvania site, whereas the site in Chile has a Mediterranean climate that is naturally dry all summer.

Computer simulations, plants grown in the greenhouse and the field-grown corn all demonstrated the same pattern: Plants with the stretch phenotype had better water capture and water transport, which led to better growth and yield under drought.

Using a genome-wide association study — a research method that scans the DNA of many corn plants to find genetic variations linked to a specific trait — the researchers found DNA markers associated with longer xylem vessel elements and perforation plate height. That shows these traits are at least partly genetically controlled, Lynch noted.

In the study, cryo-scanning electron microscopy — an imaging technique that allows scientists to view delicate samples such as biological tissues by flash-freezing them first — was used for closer observation of xylem perforation plates. This work was completed at Penn State’s Huck Institutes of the Life Sciences Microscopy Core Facility.

The researchers used laser ablation tomography — an advanced imaging technique developed by the Lynch lab a decade ago that combines a pulsed UV laser and serial imaging to capture high-resolution, three-dimensional images of corn root cross sections — to view the differences between corn plants with and without longer xylem vessel elements and lower perforation plate height.

This study’s findings suggest that plant breeders could improve drought tolerance in corn by selecting for plants with the stretch phenotype, Lynch noted. The stretch syndrome the team detected was characterized by the researchers as “pleiotropic,” meaning it occurs when a single genetic location affects multiple, seemingly unrelated traits. In this case, Lynch explained, the syndrome appears to be controlled by one or two major genes, which makes it easier to isolate.

“The seed companies are always interested in traits that can be used to breed better crops, and certainly drought is the biggest risk to crop production anywhere on Earth, including in rich countries like the U.S.,” he said. “Farmers do not usually irrigate corn, so they’re depending on the climate, which is quite variable. For example, this year significant parts of the U.S. corn belt have been pretty dry. So, anything we can do to improve corn’s ability to withstand drought would be important. The findings from this research identify a potential avenue to breed more drought-tolerant crops.”

Penn State-affiliated contributors include first author and lead researcher Christopher Strock, a postdoctoral scholar in the Lynch lab when the study was done, now crop phenotyping scientist with John Deere; Cody DePew, Penn State research technologist in plant sciences; and Jagdeep Sidhu, who earned his doctorate in agricultural and environmental plant science at Penn State, currently an assistant professor of root biology at the University of Missouri. A full list of authors and their affiliations are available in the paper.

This research was supported by the Foundation for Food and Agriculture Research’s Crops of the Future and the U.S. Department of Agriculture National Institute of Food and Agriculture.

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Journal

Crop Science

DOI

10.1002/csc2.70287 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

A pleiotropic “stretch” phenotype is associated with metaxylem vessel element length, axial hydraulic conductance, root elongation, water utilization, and drought adaptation in maize

Corn leaf samples collected in the field at both research sites (Chile shown here) were analyzed for their biomass and prepared for later anatomical analysis at Penn State. 

Corn root samples were collected in the field both in Pennsylvania and Chile, then preserved in alcohol for later analysis by laser ablation tomography and/or cryo-scanning electron microscopy in the laboratory at Penn State. 

A longitudinal section and a cross-section of corn roots showing perforation plates within the metaxylem vessels and metaxylem vessel element length are shown in these images generated by cryo-scanning electron microscopy. Long, smooth vessels conduct faster flow, creating a more efficient water-transport system, the researchers reported. 

Credit

Christopher Strock/Penn State

New holographic printer makes 3D shapes in one shot

University of Utah engineers’ method uses nanoscale ‘mask’ to avoid leaky seams that come with standard layering process

University of Utah

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Rajesh Menon, a professor of electical and computer engineering at the University of Utah.

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Credit: Dan Hixson, University of Utah

University of Utah researchers have demonstrated a new method of 3D printing that avoids the leaky seams that come with the layer-by-layer process. Using a nanoscale “mask” that diffracts laser light into a holographic pattern of the desired shape, it fuses its print material solid in one shot. The process takes about 20 seconds, a stark contrast with the hours other laser-based printing methods can take.

In a study published in the journal Nature Communications, the researchers demonstrated they could print multiple shapes in a conveyor-belt fashion. The research was led by Rajesh Menon, professor in the Department of Electrical & Computer Engineering at the Price College of Engineering, along with lab member Dajun Lin.

Menon’s team used this technique to print microtubule assemblies with individual diameters as small as 6 micrometers. They tested their assemblies for physical toughness and also showed they could transport liquid via the capillary effect.

The project takes inspiration from photolithography, but applies the concept to three dimensions.

The researchers’ prints are made of a substrate called SU-8, commonly used in photolithography. Made of stringy polymers, those molecular threads crosslink and harden when exposed to laser light. The unexposed sections of the substrate can then be easily washed away, leaving the desired shape behind.

In 2D photolithography, that shape is controlled by an opaque mask that blocks the laser from reaching the unwanted parts of the substrate. This approach is fine for two dimensions, since light only needs to reach the substrate’s surface.

To apply the concept to three dimensions, the laser must pass through the substrate itself, crosslinking a volume of space inside. The challenge there is accuracy; because the substrate isn’t perfectly transparent, it will deflect the path of the laser as it passes through, causing blurring.

Menon’s group devised a way around the blurring problem: a mask consisting of a nanopatterned lens that compensates for the substrate’s diffraction. Placed in front of the light source, the mask channels the laser’s energy only to the volume of substrate that will become the final print.

To demonstrate the printer, the researchers made a variety of complex microstructures, with dimensional ratios as high as 120:1. Menon describes these prints as “extended 2D” rather than true 3D — while they have length, width and height, the researchers can only control the shape of the former two dimensions.
“The mask is working like a cookie cutter, stamping a complex shape out of thick dough,” Menon said. “The laser is ‘baking’ the dough on the inside at the same time, so the resulting shape is physically tough.”

The researchers produced multiple lattice patterns for their microtubule arrays. The technique’s limitations lend themselves to lattice-like microtubule patterns, as they have extreme fine details in two dimensions that are extended as far as possible into the third. In subsequent experiments, the researchers demonstrated that these microtubules could successfully transport liquid via capillary action, as well as withstand various compression tests.

The researchers are now working to achieve true 3D prints using their new technique.

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The study appeared June 4 in the Nature Communications under the title, “Single-exposure holographic lithography of ultra-high aspect-ratio microstructures.” Brian Baker of the Utah Nanofab is a co-author. The underlying research was supported by the National Science Foundation and the University of Utah.

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Journal

Nature Communications

DOI

10.1038/s41467-026-73975-4 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Single-exposure holographic lithography of ultra-high aspect-ratio microstructures

Article Publication Date

4-Jun-2026

COI Statement

Rajesh Menon has financial stake in Oblate Optics, Inc. which is commercializing inverse-designed flat optics. R.M. is a co-inventor of a related patent filed by University of Utah and the University of Texas at Austin, Serial No. WO202525956. R.M. is a co-inventor of a related granted patent (2015) US 8,953,239. The remaining authors declare no competing interests.

 

The researchers demonstrated multiple different lattice patterns for their microtubule arrays.

Credit

Menon Lab, University of Utah