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Generating hydrogen without releasing carbon dioxide sounds simple: pass electricity through water, split water molecules and generate green hydrogen. The hard part is the electrocatalyst. The best ones rely on platinum, ruthenium and iridium, which are scarce and expensive. We wanted to know whether a small amount of iron and nickel oxides, anchored on carbon nanofibers grown by chemical vapor deposition the right way on the right scaffold, could do the job instead. Our results are published in ACS Applied Nano Materials.
Most hydrogen today comes from fossil fuels. Coal gasification and steam reforming of natural gas supply about 96% of the market. Producing 1 kilogram (2.2 pounds) of gray hydrogen releases about 10 kilograms (22 pounds) of carbon dioxide, and blue hydrogen releases about 6 kg (13 pounds). Green hydrogen, made by splitting water, avoids these emissions. Water splitting has two half-reactions: the oxygen evolution reaction at the anode and the hydrogen evolution reaction at the cathode. Both need an electrocatalyst to run at practical voltages.
Our scaffold is Ti₃C₂Tₓ MXene, a two-dimensional material that conducts electricity efficiently. MXene sheets tend to oxidize and restack, which raises resistance. We tackled this by growing carbon nanofibers directly on the sheets. We mixed the MXene with an iron or nickel precursor, dried it and heated it under nitrogen to 400°C (752°F). We then raised the temperature to 720°C (1,328°F) and fed acetylene as a carbon source for two hours, performing chemical vapor deposition to grow carbon nanofibers. The metal oxide particles sit at the tip of each growing fiber, a process called tip growth. We call the two products FeO-CNF@MX and NiO-CNF@MX.
Electron microscopy showed fibers growing across the MXene sheets, each capped with a metal oxide particle. X-ray diffraction and Raman spectroscopy showed the layered MXene structure survived the synthesis. X-ray photoelectron spectroscopy confirmed that the oxide particles were anchored on the sheets. The nickel-based composite had more graphitic, less defective carbon, with a Raman defect ratio of 0.40 against 0.68 for the iron-based one.
"Growing the fibers directly on the MXene sheets gave us a conductive backbone and a lot of accessible active sites."
We tested both materials in 1 M potassium hydroxide. Anchoring the fibers on MXene improved every catalyst compared with the fibers alone. For hydrogen evolution, NiO-CNF@MX needed an overpotential of 490 mV to reach 10 mA/cm². FeO-CNF@MX needed 520 mV. The fibers without MXene needed 570 and 550 mV, respectively.
For oxygen evolution, NiO-CNF@MX needed 300 millivolts and FeO-CNF@MX needed 360 millivolts. The nickel composite landed within 50 millivolts of the benchmark ruthenium oxide, which needed 250 mV. Charge-transfer resistance was also slightly lower for the nickel composite, at 15.5 ohms against 16.5 for iron.
Putting the same material on both electrodes of a small prototype electrolyzer changed the ranking. The iron composite reached 10 mA/cm² at 2.2 V, while the nickel composite needed 2.7 V. We think iron centers help stabilize reactive oxygen intermediates, which speeds oxygen evolution in the full cell. Over a 24-hour test, the cell voltage drifted by only 0.2 to 0.3 V for both materials. The nickel composite drifted slightly less, from 2.38 to about 2.6 V, against about 2.4 to 2.7 V for the iron one.
These catalysts do not yet match platinum, which reached 10 mA/cm² at an overpotential of 70 mV for hydrogen evolution. Our results do show that a simple, scalable route can turn low-cost metal oxides into working catalysts for both half-reactions. The iron composite showed higher initial activity in the full cell, while the nickel composite showed steadier long-term performance.
This story is part of Science X Dialog, where researchers can report findings from their published research articles. Visit this page for information about Science X Dialog and how to participate.
More informationManish Chauhan et al., Rational Design of In Situ-Grown Hierarchical Carbon Nanofiber−MXene Nanointerfaces with Iron−Nickel Oxide Nanoarchitectures for Bifunctional Electrocatalysis, ACS Applied Nano Materials (2026). DOI: 10.1021/acsanm.6c03453
Who's behind this story?
Lisa LockBA art history, MA material culture. Former museum editor, paramedic, and transplant coordinator. Editing for Science X since 2021. Full profile →
Robert EganBachelor's in mathematical biology, Master's in creative writing. Well-traveled with unique perspectives on science and language. Full profile →
Shiv Singh is a Scientist-D and Assistant Professor at CSIR–AMPRI, Bhopal, India. His research focuses on functional carbon materials, electrocatalysis, clean energy conversion, CO2 utilization, hydrogen generation, and environmental remediation. Leading DST- and DBT-funded projects as Principal Investigator, he investigates bio-electrochemical CO2 conversion, microbial electrochemical systems, and water splitting, and exploring waste-derived electrodes and electrochemical sensing.
He has published in recognized journals, secured patents, and is a member of the Royal Society of Chemistry. He holds editorial roles across multiple international journals and received the Springer Nature Author Service Award in 2025. Through multidisciplinary research and mentorship, he develops scalable solutions for global energy and environmental challenges.
Citation: Water into fuel: The new nanomaterial that could upgrade green hydrogen (2026, October 26) retrieved 26 October 2026 from https://phys.org/news/2026-10-fuel-nanomaterial-green-hydrogen.html
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