The race to turn carbon dioxide from an atmospheric liability into a useful industrial resource has taken a significant step forward. Researchers in China have developed a single-atom iron catalyst that combines unusually high activity with long-term durability, addressing one of the central obstacles facing electrochemical carbon dioxide reduction. The catalyst converts CO₂ into carbon monoxide, an important building block for producing synthetic fuels, chemicals and materials, while maintaining its performance under extended operation.
Electrochemical CO₂ reduction, commonly known as CO₂RR, uses electricity to drive chemical reactions that transform carbon dioxide into products with economic value. Carbon monoxide is among the most attractive targets because it can be combined with hydrogen in syngas, a mixture used to manufacture methanol, liquid fuels and numerous industrial chemicals. However, the process requires catalysts that can activate the chemically stable CO₂ molecule efficiently while suppressing competing reactions, particularly hydrogen evolution.
Iron–nitrogen–carbon catalysts, often abbreviated as Fe-N-C, have attracted considerable attention because they contain isolated iron atoms coordinated by nitrogen atoms within a conductive carbon framework. These atomically dispersed iron sites can selectively bind and activate reaction intermediates. Yet their practical application has been limited by a persistent trade-off: modifications that increase catalytic activity can weaken the metal-support structure, causing iron atoms to migrate, dissolve or leach into the electrolyte during operation.
A research team led by Dr. Chaoyun Ma of Xinjiang University and Prof. Hao Jiang of East China University of Science and Technology has now proposed a strategy designed to overcome this conflict. Their catalyst, called ZnS@Fe-NSC, contains isolated Fe-N₄ sites, sulfur-doped carbon and neighboring zinc sulfide nanoparticles. The material was reported in Nano Research, where the researchers describe how these components work together rather than functioning as independent additives.
The catalyst is produced through an in-situ sulfidation process using a single sulfate-containing precursor. During pyrolysis, an iron-doped zinc-based metal-organic framework known as ZIF-8 is converted into a porous carbon structure. The iron atoms become embedded in nitrogen-coordinated sites, while the sulfate species decompose and provide sulfur. Some of the sulfur atoms enter the carbon matrix, changing its electronic properties, while others react with zinc to form nanoscale ZnS particles. This one-step synthesis creates a closely integrated architecture that would be difficult to reproduce by simply mixing separately prepared components.
At the atomic level, sulfur doping modifies the electronic environment surrounding the Fe-N₄ centers. According to the researchers, this adjustment lowers the energy barrier associated with the formation of *COOH, a key surface-bound intermediate in the pathway from CO₂ to CO. Reducing the energy required to generate this intermediate allows the reaction to proceed more readily. At the same time, the adjacent ZnS nanoparticles act as electron donors, transferring electronic density toward the iron centers and strengthening the bonds that anchor iron within the nitrogen-rich carbon framework.
This electronic interaction is important because the catalyst must survive in a chemically and electrochemically demanding environment. Under CO₂RR conditions, unstable iron sites may detach from the carbon support or undergo structural changes that reduce their activity. The researchers found that the ZnS component provides a protective effect, helping stabilize the Fe-N₄ configuration and limiting iron loss. Their measurements indicated that ZnS@Fe-NSC reduced iron leaching by more than twentyfold compared with less integrated reference catalysts.
The performance results were equally notable. At an overpotential of −0.58 volts versus the reversible hydrogen electrode, ZnS@Fe-NSC achieved a Faradaic efficiency for carbon monoxide of 99.53 percent. Faradaic efficiency measures the proportion of electrons that produce the desired product, so a value approaching 100 percent indicates highly selective conversion with minimal diversion toward unwanted reactions. More than 90 percent CO selectivity was retained during 30 hours of continuous electrolysis, whereas control materials lacking the combined sulfur and ZnS modification lost more than half of their initial activity over a comparable period.
The researchers also tested the catalyst in a rechargeable zinc–carbon dioxide battery, moving beyond a laboratory electrolysis cell toward an integrated energy-conversion device. The battery reached a peak power density of 6.2 milliwatts per square centimeter and operated for 125 hours without major performance loss. It was even able to power a small light-emitting diode, demonstrating that the system could simultaneously store energy and convert carbon dioxide into a useful chemical product. Although further engineering will be needed for commercial deployment, the result highlights the potential of coupling CO₂ conversion with metal-based energy-storage technologies.
The study offers a broader design principle for catalyst development: improving the electronic activity of an isolated metal site does not necessarily have to undermine its structural stability if neighboring components are deliberately positioned to reinforce it. By combining sulfur-modified carbon with electron-donating ZnS nanoparticles, the team created a cooperative environment in which reaction kinetics and metal retention are enhanced at the same time. The researchers say the approach could be adapted to other electrochemical reactions, including water splitting and oxygen reduction in fuel cells. If the architecture can be reproduced at larger scale and under industrially relevant current densities, it could help move electrochemical carbon recycling closer to practical carbon-neutral manufacturing.
Subject of Research: Electrochemical carbon dioxide reduction using a synergistically engineered iron-based single-atom catalyst.
Article Title: Synergistic design overcomes activity-stability trade-off in iron-based catalysts for efficient CO₂ conversion
News Publication Date: 19 May 2026
Web References: https://doi.org/10.26599/NR.2026.94908640; Nano Research
References: Nano Research, DOI: 10.26599/NR.2026.94908640
Image Credits: Nano Research, Tsinghua University Press
Keywords
CO₂ reduction, carbon dioxide conversion, carbon monoxide, single-atom catalyst, Fe-N-C, Fe-N₄, ZnS nanoparticles, sulfur doping, electrochemical catalysis, carbon recycling, zinc–CO₂ battery, Nano Research
