Using AI to improve nickel catalysts for converting carbon dioxide into methane

Advanced Institute for Materials Research (AIMR), Tohoku University

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The complete process of machine learning-driven CO2 methanation catalyst design.

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Credit: Jiayi Zhang et al.

The conversion of carbon dioxide into clean fuels is regarded as an important route toward carbon neutrality. CO2 methanation, in particular, has drawn increasing interest due to its favorable thermodynamic properties and environmental benefits. Yet, large-scale deployment continues to face challenges such as insufficient catalyst activity at low temperatures and vulnerability to carbon deposition.

Researchers have now applied an explainable machine learning (ML) framework to support the rational design of nickel-based catalysts for CO2 methanation. Instead of relying on traditional trial-and-error methods, the study introduces a systematic approach for data processing, cross-validation, and ensemble learning model construction. Among the tested methods, a categorical boosting (CatBoost) model achieved R² values of 0.77 for CO2 conversion and 0.75 for CH4 selectivity.

By analyzing key descriptors, the study identified optimal reaction conditions: temperature between 250-350 °C, gas hourly space velocity below 15,000 cm³ g⁻¹ h⁻¹, BET surface area of 50-200 m² g⁻¹, and nickel content higher than 5%. These insights demonstrate how data-driven methods can guide catalyst optimization and shorten the pathway from laboratory research to industrial application.

"This work shows how machine learning can help us better understand the critical factors influencing CO2 methanation performance," said Hao Li, a Distinguished Professor at Tohoku University's Advanced Institute for Materials Research (WPI-AIMR. "By making the models explainable, we are not only predicting results but also gaining knowledge about why certain conditions matter."

Looking ahead, the research team will integrate density functional theory calculations and high-throughput experimental data to build multi-scale predictive models. They will also conduct systematic experimental validation to refine catalyst designs.

"Our goal is to establish a platform that combines computational chemistry, machine learning, and catalytic engineering," Li explained. "In doing so, we hope to contribute practical solutions for carbon recycling and the efficient use of renewable energy." This study provides a perspective on how explainable machine learning can be applied to catalyst research, supporting both the development of cleaner fuels and the broader transition to sustainable energy systems.

The study was published in the journal ACS Sustainable Chemistry & Engineering on August 22, 2025.

About the World Premier International Research Center Initiative (WPI)

The WPI program was launched in 2007 by Japan's Ministry of Education, Culture, Sports, Science and Technology (MEXT) to foster globally visible research centers boasting the highest standards and outstanding research environments. Numbering more than a dozen and operating at institutions throughout the country, these centers are given a high degree of autonomy, allowing them to engage in innovative modes of management and research. The program is administered by the Japan Society for the Promotion of Science (JSPS).

See the latest research news from the centers at the WPI News Portal: https://www.eurekalert.org/newsportal/WPI
Main WPI program site:  www.jsps.go.jp/english/e-toplevel

Advanced Institute for Materials Research (AIMR)
Tohoku University
Establishing a World-Leading Research Center for Materials Science
AIMR aims to contribute to society through its actions as a world-leading research center for materials science and push the boundaries of research frontiers. To this end, the institute gathers excellent researchers in the fields of physics, chemistry, materials science, engineering, and mathematics and provides a world-class research environment.
 

Data processing and model building process for machine learning modeling of CO2 methanation catalysts.

By comparing the performance of three machine learning algorithms, XGBoost, Random Forest, and CatBoost, in catalyst performance prediction, the differences in the advantages of different algorithms in specific tasks are revealed. 

Credit

Jiayi Zhang et al.

Journal

ACS Sustainable Chemistry & Engineering

DOI

10.1021/acssuschemeng.5c02957 

Article Title

Application of an Explainable Machine Learning to CO2 Methanation for Optimal Design Nickel-Based Catalysts

A ‘wasteful’ plant process makes a key prenatal vitamin. Climate change may reduce it.

MSU scientists uncover the hidden link between plant metabolism, climate change and a vitamin essential for healthy pregnancies

Michigan State University

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Michigan State University researcher Berkley Walker measures how much CO2 a plant takes in by clamping its leaves in an infrared gas analyzer.

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Credit: Finn Gomez

New research from Michigan State University reveals that photorespiration – long considered a wasteful process – is essential for producing a crucial nutrient for preventing birth defects.

For the first time, scientists have measured how much carbon flows through photorespiration to make folates, a class of compounds that includes vitamin B9 – known for its importance as a prenatal vitamin. According to the study, led by MSU researcher Berkley Walker, about 6 percent of the carbon absorbed by plants is used to make folates. That number plummets by fivefold when photorespiration is suppressed.  

These findings, published in Nature Plants, could help scientists engineer plants to boost production of the nutrient important for human health. They also shed light on how a high-carbon dioxide world caused by climate change could make plants less nutritious.

“In cultures where the bulk of their calories come from rice, it’s a pretty big deal if that rice is less nutritious,” said Walker, an associate professor in the MSU-DOE Plant Research Laboratory and the Department of Plant Biology. “The way plants respond to changing climates is complicated. Understanding how they might adapt can help us plan better for the future.”

Plants are like factories, using the raw materials of sunlight, water and carbon dioxide, or CO2, to make sugar they use for food. The foreman of this factory is an enzyme called rubisco, which grabs CO2 and feeds it into the production line.

But sometimes, rubisco gets sloppy on the job and accidentally grabs oxygen, clogging up the assembly line and producing a toxic byproduct called phosphoglycolate. That’s when a recycling crew springs into action. In a process called photorespiration, plants neutralize the toxic waste and salvage it into useful compounds.

Scientists have long suspected that photorespiration supported processes like making folates. Until now, it was unclear how much carbon photorespiration contributed to making that vitamin.

To crunch the numbers, Walker and his lab tested a common model plant, called Arabidopsis thaliana. They measured the plant under conditions with or without photorespiration and measured how much CO2 the plant took in by clamping its leaves in an infrared gas analyzer. Then, they sprayed the leaves with liquid nitrogen while still clamped to freeze them immediately. This helped them understand what the leaf was doing while being measured.

Walker’s team used mass spectrometry to examine the leaf’s chemicals and how they incorporated CO2 over time. Then, they repeated the process for several months, measuring chemical content at different points before plugging the measurements into a computational analysis.

The results provide a stark look at how plant nutrition could change. As the CO2 in the air increases, plants need photorespiration less often. MSU’s study found that in those circumstances, the carbon flow to produce vitamin B9 dropped from nearly 6 percent to about 1 percent. That’s significant, as vitamin B9 is important during pregnancy to reduce the risk of neural tube defects.

“Understanding how nature makes this vitamin will help us engineer plants fortified with this nutrient,” Walker said. “That may become necessary especially in cultures where people can’t simply take a multivitamin to make up for less nutritious plants.”

The Walker lab’s next step is conducting similar experiments with crop plants grown outdoors. They want to know whether the same trends inside the lab are true for plants grown out in the field.

The National Science Foundation-funded project is another example of critical research that lays the foundation for the future.

“We need this knowledge about plants in order to engineer them for the future,” Walker said. “If we don’t have that foundation, we’ll never to get to the application.”

By Bethany Mauger

Michigan State University researcher Berkley Walker used liquid nitrogen to freeze plant leaves while they were still being measured by an infrared gas analyzer.

Michigan State University researcher Berkley Walker pours liquid nitrogen to flash-freeze plant leaves while still being measured by an infrared gas analyzer.

Credit

Finn Gomez

Journal

Nature Plants

DOI

10.1038/s41477-025-02091-w 

Article Title

Metabolic flux analysis in leaf metabolism quantifies the link between photorespiration and one carbon metabolism

Article Publication Date

3-Sep-2025

 SPACE/COSMOS

Solar flares over 6 times hotter than previously thought

University of St. Andrews

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A solar limb flare with a comparatable scale of Earth 

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Credit: Created by Alexander Russell (University of Andrews) using the open-source SunPy Python package and data from NASA’s Solar Dynamics Observatory space telescope via NASA EPIC Team

New research from the University of St Andrews has proposed that particles in solar flares are 6.5 times hotter than previously thought and provided an unexpected solution to a 50-year-old mystery about our nearest star. 

Solar flares are sudden and huge releases of energy in the Sun’s outer atmosphere that heat parts of it to greater than 10 million degrees. These dramatic events greatly increase the  solar X-rays and radiation reaching Earth and are hazardous to spacecraft and astronauts, as well as affecting our planet’s upper atmosphere. 

The research, published today in Astrophysical Journal Letters, looked at evidence of how flares heat solar plasma to greater than 10 million degrees. This solar plasma is made up of ions and electrons. The new research argues that solar flare ions, positively charged particles that make up half of the plasma, can reach over 60 million degrees. 

Looking at data from other research areas, the team, led by Dr Alexander Russell, Senior Lecturer in Solar Theory from the School of Mathematics and Statistics, realised that solar flares are very likely to heat the ions more strongly than the electrons. 

Dr Russell, said: “We were excited by recent discoveries that a process called magnetic reconnection heats ions 6.5 times as much as electrons. This appears to be a universal law, and it has been confirmed in near-Earth space, the solar wind and computer simulations. However, nobody had previously connected work in those fields to solar flares.” 

 “Solar physics has historically assumed that ions and electrons must have the same temperature. However, redoing calculations with modern data, we found that ion and electron temperature differences can last for as long as tens of minutes in important parts of solar flares, opening the way to consider super-hot ions for the first time.” 

“What’s more,” he added, is that the new ion temperature fits well with the width of flare spectral lines, potentially solving an astrophysics mystery that has stood for nearly half a century.” 

There has been a long-standing question since the 1970s about why flare spectral lines, bright enhancements in the solar radiation at specific “colours” in extreme-ultraviolet and X-ray light, are broader than expected. Historically, it was believed that this could only be due to turbulent motions, but that interpretation has come under pressure as scientists have tried to identify the nature of the turbulence. After nearly 50 years, the new work argues for a paradigm shift where the ion temperature can make a large contribution to explaining the enigmatic line widths of solar flare spectra. 

Solar flares

Credit

Created by Alexander Russell (University of Andrews) using the open-source SunPy Python package and data from NASA’s Solar Dynamics Observatory space telescope via NASA EPIC Team

Journal

The Astrophysical Journal Letters

DOI

10.3847/2041-8213/adf74a 

Method of Research

Data/statistical analysis

Subject of Research

Not applicable

Article Title

Solar Flare Ion Temperatures

Article Publication Date

3-Sep-2025

SwRI-proposed mission could encounter and explore a future interstellar comet like 3I/ATLAS up close

Development study sets mission objectives and trajectory of journey to interstellar comet, as well as probability of success in locating a target

Southwest Research Institute

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Upper left panel: Comet 3I/ATLAS as observed soon after its discovery. Upper right panel: Halley’s comet’s solid body as viewed up close by ESA’s Giotto spacecraft. Lower panel: The path of comet 3I/Atlas relative to the planets Mercury through Saturn and the SwRI mission interceptor study trajectory if the mission were to be launched this year. The red arc in the bottom panel is the mission trajectory from Earth to interstellar comet 3I/ATLAS.

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Credit: NASA/ESA/UCLA/MPS

SAN ANTONIO — September 3, 2025 — Southwest Research Institute (SwRI) has completed a mission study detailing how a proposed spacecraft could fly by an interstellar comet, providing remarkable insights into the properties of bodies originating beyond our solar system. The internally funded SwRI project developed the mission design, scientific objectives, payload and key requirements based on previous interstellar object (ISO) detections. Using the recent discovery of 3I/ATLAS, the team validated the mission concept, determining that 31/ATLAS could have been intercepted and observed by the proposed spacecraft.

In 2017, the object designated 1I/‘Oumuamua became the first interstellar comet (ISC) detected in the solar system. Its identification and naming nomenclature starts with the number 1, because it’s the first such object to be discovered, followed by an “I” for interstellar, and “ʻOumuamua,” which is the object’s given name — a Hawaiian word meaning “a messenger from afar arriving first.” Its discovery was soon followed by the discovery of the second interstellar comet, ISC 2I/Borisov in 2019, and now this year, ISC 3I/ATLAS, which made worldwide headlines as it became the third officially recognized interstellar object to cross into our solar system. As new astronomical facilities like the National Science Foundation’s Vera Rubin Observatory develop new surveys and those capabilities expand, astronomers expect to discover many more ISCs over the next decade.
“These new kinds of objects offer humankind the first feasible opportunity to closely explore bodies formed in other star systems,” said SwRI Associate Vice President Dr. Alan Stern, a planetary scientist who led the study project. “An ISC flyby could give unprecedented insights into the composition, structure and properties of these objects, and it would significantly expand our understanding of solid body formation processes in other star systems.”

Scientists estimate that numerous interstellar objects of extrasolar origin pass inside Earth’s orbit each year, and that as many as 10,000 pass inside the Neptune’s orbit in any given year. The SwRI-led internal research study tackled the unique design challenges and defined the costs and payload needs associated with an ISC mission. The mission concept could be later proposed to NASA. The hyperbolic trajectories and high velocities of these objects preclude orbiting them with current technology, but the SwRI study showed that flyby reconnaissance is feasible and affordable.

“The trajectory of 3I/ATLAS is within the interceptable range of the mission we designed, and the scientific observations made during such a flyby would be groundbreaking,” said SwRI’s Matthew Freeman, the study’s project manager.” The proposed mission would be a high-speed, head-on flyby that would collect a large amount of valuable data and could also serve as a model for future missions to other ISCs.”

SwRI scientists and their external collaborators in the study established the major, comprehensive scientific objectives for a mission to an ISC. Determining the physical properties of the body would offer insights to its formation and evolution. Examining the ISC composition could help explain its origins and interpret how evolutionary forces have affected the comet since its formation. Yet another objective is to thoroughly investigate the nature of the object’s coma, the escaping atmosphere emanating from its central body.

To develop mission trajectory options, SwRI developed software that generated a representative, synthetic population of ISCs then calculated a minimum energy trajectory from Earth to the path of each comet. The software’s calculations showed that a low-energy rendezvous trajectory is possible, and in many cases would require less launch and in-flight velocity change resources than many other solar system missions. SwRI orbital mechanics expert, Dr. Mark Tapley, used this software to calculate the trajectory that the proposed spacecraft could have taken from Earth to intercept 3I/ATLAS. He found that the mission designed by SwRI’s study could have reached 3I/ATLAS.

“The very encouraging thing about the appearance of 3I/ATLAS is that it further strengthens the case that our study for an ISC mission made,” said Tapley. “We demonstrated that it doesn’t take anything harder than the technologies and launch performance like missions that NASA has already flown to encounter these interstellar comets.”

For more information, visit https://www.swri.org/markets/earth-space/space-research-technology.

 

Countries’ carbon budget math is broken

How flawed calculations let high-polluting countries off the hook, and how courts can hold them accountable

Utrecht University

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The figure shows how national climate pledges (NDCs) compare with global pathways that would limit warming to between 1.5°C and 4°C. Under the approach as proposed in the research, global emissions are divided up in a way that reflects fairness and equity. The colors show whether a country’s pledge is strong enough to match a 1.5°C pathway or instead lines up with weaker pathways (2°C, 3°C, or 4°C).

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Credit: Yann Robiou du Pont, et al., Nature Communications.

Climate action is falling behind on the goals as stated in the Paris Agreement. To meet those goals, countries must act according to their ‘fair share’ targets. However, researchers from Utrecht University found a bias in how ambition and fairness assessments were calculated until now: “previous studies assessing countries climate ambition share a feature that rewards high emitters at the expense of the most vulnerable ones.” This finding influences climate change mitigations globally. The research, led by Yann Robiou du Pont, was published on 3 September in Nature Communications.

The researchers argue that previous fairness and ambition assessments were biased, as they start from shifting goalposts of rising emissions. Their proposed method avoids delaying the obligation to reduce emissions and calculates the immediate ambition gap that can be filled by climate measures and international finance. As negotiated climate targets are still insufficient, this work underscores the growing role of courts in ensuring that climate and human rights obligations are met. The study highlights that high-emitting countries, most notably G7 countries, Russia, and China, need to do more given the very different historical responsibility and financial capability of countries.

An approach based on historical responsibility needed

Fair-share emissions allocations distribute the global carbon budget among countries based on principles like historical responsibility, capability, and development needs, aiming to assign each country a ‘fair share’ of allowable emissions. Under the Paris Agreement, these allocations indicate what each country should commit to in order to collectively limit global warming to 1.5°C and staying well below 2°C. 

By calculating each ambition and fairness assessment from the present situation, we increasingly let major polluting countries off the hook. This pushes a heavier burden onto countries that have done the least to cause the crisis, or more realistically brings the world towards catastrophic levels of global warming. Therefore, the authors propose calculating fair-share emissions allocations immediately based on each country’s historical contributions to climate change and their capacity to act. Accounting for immediate responsibilities sets a new baseline. It would cause some countries’ emission paths to suddenly and drastically change instead of following a smooth decline. This approach would demand steep, immediate cuts mostly from wealthier, high-emitting countries. Since the cuts needed from these countries are too large to achieve locally, it requires substantial financial support for additional mitigation in poorer countries. Importantly, removing the systemic reward for inaction affects the ranking of countries’ gap between their current pledges and fair emissions allocations, even within the group of high-income countries. Then, the USA, Australia, Canada, the UAE and Saudi Arabia have the greatest gap, requiring the most additional effort and finance. Much of equity discussions is about developed versus developing countries, but this paper is particularly relevant for developed countries being rewarded for inaction compared to other and more ambitious developed countries.

Role in climate litigation

Fair-share studies like this one are increasingly used in climate litigation, such as the KlimaSeniorinnen case before the European Court of Human Rights. The court recognised that insufficient national climate action constitutes a breach of human rights and that countries must justify how their climate pledges are a fair and ambitious contribution to the global objectives. Courts rely on these assessments to evaluate whether national emissions targets are sufficient and equitable. Biases in the assessments therefore have real-world impact: they can shape legal rulings, influence policy commitments, and inform public opinions. Courts are thus emerging as a key force in ensuring accountability and indirectly promoting cooperation when political and diplomatic negotiations fall short. In a landmark advisory opinion issued on July 23, 2025, the International Court of Justice affirmed that countries have a legal obligation under international law to prevent significant harm to the climate system, emphasising the duty to act collectively and urgently. “This strengthens and underscores the growing role of courts in enforcing climate justice,” says Robiou du Pont.

Paying the debt

Solving the climate crisis is a moral imperative long identified by climate justice activists and scholars. Practically, we are observing that the lack of fair efforts by countries with the greatest capacity and responsibility to act and provide finance, results in insufficient action globally. A fairer allocation of effort is likely to results in more ambitious outcomes globally. This study explains how immediate climate efforts and finance are key to align with international agreements to limiting global warming.

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Journal

Nature Communications

DOI

10.1038/s41467-025-62947-9 

Method of Research

Computational simulation/modeling

Subject of Research

Not applicable

Article Title

Effect of discontinuous fair-share emissions allocations immediately based on equity.

Article Publication Date

3-Sep-2025