Unexpected Discovery Leads to a Catalyst That Improves Over Time

Scientists have developed a revolutionary catalyst that not only converts CO2 into valuable products but actually increases in activity over time.

Made from tin microparticles on a nanotextured carbon structure, this innovative electrocatalyst efficiently produces formate—a key compound for various industries. Unlike conventional catalysts that degrade, this one self-optimizes by breaking down into smaller tin nanoparticles, dramatically improving performance.

Breakthrough Catalyst for CO₂ Conversion

Scientists have developed a sustainable catalyst that becomes more effective as it operates, converting carbon dioxide (CO₂) into valuable products. This breakthrough provides a foundation for designing next-generation electrocatalysts.

A research team from the University of Nottingham’s School of Chemistry and the University of Birmingham created the catalyst using tin microparticles supported by a nanotextured carbon structure. The interaction between the tin particles and graphitized carbon nanofibers plays a crucial role in transferring electrons from the carbon electrode to CO₂ molecules—an essential step in converting CO₂ into formate when an electric potential is applied.

These findings were published today (February 10) in ACS Applied Energy Materials, a journal of the American Chemical Society that focuses on interdisciplinary research in materials for energy applications.

Addressing CO₂ Emissions with Electrocatalysis

CO₂ is the primary contributor to global warming. While CO₂ can be converted into useful products, traditional thermal methods typically rely on hydrogen sourced from fossil fuels. Therefore, it is essential to develop alternative methods like electrocatalysis, which utilizes sustainable energy sources, such as photovoltaics and wind power, as well as the abundant availability of water as a hydrogen source.

In electrocatalysis, applying an electric potential to the catalyst drives electrons through the material to react with CO₂ and water, producing valuable compounds. One such product, formate, is widely used in the chemical synthesis of polymers, pharmaceuticals, adhesives, and more. For optimal efficiency, this process must operate at low potential while maintaining high current density and selectivity, ensuring effective use of electrons to convert CO₂ to desired products.

Bubbles of CO2 passing through the electrochemical reactor dissolve in water and react with the help of the electrocatalyst to form various products. Credit: University of Nottingham

Nanotextured Carbon Enhances Catalyst Performance

Dr. Madasamy Thangamuthu, a research fellow at the University of Nottingham co-led the research team, he said: “A successful electrocatalyst must strongly bond to the CO₂ molecule and efficiently inject electrons to break its chemical bonds. We developed a new type of carbon electrode that incorporates graphitized nanofibers with a ” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]” tabindex=”0″ role=”link”>nanoscale texture, featuring curved surfaces and step edges, to enhance interaction with tin particles.”

Tom Burwell, a research assistant at the University of Nottingham undertook the work whilst studying at Centre for Doctorial Training in Sustainable Chemistry. He developed the approach and carried out the experimental work, he said: “We can assess the performance of the catalyst by measuring the electrical current consumed by the reacting CO₂ molecules. Typically, catalysts degrade during use, resulting in decreased activity. Surprisingly, we observed the current flowing through tin on nanotextured carbon increased continuously over 48 hours. Analysis of the reaction products confirmed nearly all electrons were utilized to reduce CO₂ to formate, boosting productivity by a factor of 3.6 while maintaining nearly 100% selectivity.”

Tin Nanoparticles Boost Efficiency

The researchers linked this self-optimisation to the tin microparticles breaking down into nanoparticles, as small as 3 nm, during the CO₂ reduction reaction. Tom Burwell elaborated: “Using electron microscopy, we found that smaller tin particles achieved better contact with the nanotextured carbon of the electrode, improving electron transport and increasing the number of active tin centers nearly tenfold.”

This transformative behavior differs significantly from previous studies, where structural changes in catalysts are often seen as detrimental. Instead, the carefully engineered support in the catalyst developed by the Nottingham team allows for dynamic adaptation of tin and improved performance.

Sustainable Solutions for a Net-Zero Future

Professor Andrei Khlobystov, School of Chemistry, University of Nottingham, said: “CO₂ is not only a well-known greenhouse gas but also a valuable feedstock for the production of chemicals. Consequently, designing new catalysts from earth-abundant materials like carbon and tin is vital for sustainable CO₂ conversion and achieving the UK’s net-zero emissions target. Our catalysts must also remain active over extended use to ensure best value.”

This discovery marks a step change in understanding the design of supports for electrocatalysis. By precisely controlling the interaction between the catalysts and their supports at the nanoscale, the team has laid the groundwork for highly selective and stable catalysts to convert CO₂ into valuable products.

This work is funded by the EPSRC Program Grant ‘Metal atoms on surfaces and interfaces (MASI) for sustainable future’ which is set to develop catalyst materials for the conversion of three key molecules – carbon dioxide, hydrogen, and ammonia – crucially important for the economy and environment. MASI catalysts are made in an atom-efficient way to ensure sustainable use of chemical elements without depleting supplies of rare elements and making most of the earth’s abundant elements, such as carbon and base metals.

Reference: 10 February 2025, ACS Applied Energy Materials.
DOI: 10.1021/acsaem.4c02830

The University of Nottingham is dedicated to championing green and sustainable technologies. The Zero Carbon Cluster has been recently launched in the East Midlands to accelerate the development and deployment of innovation in green industries and advanced manufacturing.