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Interpretable machine learning-guided plasma catalysis for hydrogen production

Abstract

Low-carbon ammonia decomposition via nonthermal plasma is a promising method for on-site hydrogen production, but finding optimal catalysts is challenging. Here we use multiscale simulations to link catalytic activity to nitrogen adsorption energy (EN) and identify the best catalysts for conventional heating and nonthermal plasma: Ru and Co, respectively. With an ideal EN of −0.51 eV for plasma catalysis, we applied machine learning to screen 3,300+ catalysts and designed efficient, earth-abundant alloys such as Fe3Cu, Ni3Mo, Ni7Cu and Fe15Ni. Plasma catalytic experiments at 400 °C further validated that the above alloys achieved higher conversions than the individual metals, and they also have comparable performance to Co. Our techno-economic analysis demonstrated potential economic benefits of plasma catalytic ammonia decomposition over Ni3Mo, highlighting a H2 production cost below the US$1 per kg H2 target and a low carbon footprint of ~0.91 kg of CO2 per kg H2.

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Fig. 1: BEP relationship between activation energy and reaction energy for NH3 decomposition over flat catalyst surfaces.
Fig. 2: Multiscale simulations for NH3 decomposition across various catalysts under the conditions of thermal heating only.
Fig. 3: MKM results in plasma catalytic ammonia decomposition.
Fig. 4: Interpretable machine learning (ML) model for predicting EN over bimetallic surfaces.
Fig. 5: Experimental validation of NH3 decomposition under heating only and NTP conditions.
Fig. 6: Comparative TEA and carbon footprint analysis for NH3 decomposition under thermal and NTP conditions.

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Data availability

Source data are provided with this paper. Data used for developing MKM, machine learning models, experimental work and TEA are available in Supplementary Data 1.

Code availability

The microkinetic models and the machine learning algorithms are included as Python modules, and data files used to create all the plots are provided in Supplementary Data 1.

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Acknowledgements

F.C., S.A.I. and C.M. acknowledge the support provided by the Department of Energy, Basic Energy Science, Catalysis Science, Early Career Research Program under award number DE-SC0024553. F.C., Q.L., Y.L. and J.Y. acknowledge the support by the Department of Energy, Fusion Energy Science, under award number DE-SC0025553 for developing the mechanism of plasma-induced radical–surface interactions and DFT-free machine learning workflow. F.C., S.A.I. and C.M. extend their thanks for the computational resources provided by Unity at Massachusetts Green High Performance Computing Center (MGHPCC), as well as the San Diego Supercomputer Center at University of California San Diego, and the Texas A&M High Performance Research Computing FASTER cluster, through allocation numbers CHM220074 and CHE200076 from the Advanced Cyberinfrastructure Coordination Ecosystem: Services & Support (ACCESS) program. This research used the resources of the National Energy Research Scientific Computing Center (NERSC), a US Department of Energy Office of Science User Facility supported by the Office of Science of the US Department of Energy under contract number DE-AC02-05CH11231 using NERSC awards BES-ERCAP0027465 and BES-ERCAP0028368. Y.Y. acknowledges financially support by the National Natural Science Foundation of China (grant numbers 22472018, 22272015 and 21503032), Y.Y., S.M. and Y.S. acknowledge support from Frontier Science Center for Smart Materials and assistance from Instrumental Analysis Center (X. Gao), Dalian University of Technology for characterization of the catalysts. We acknowledge H. Liu for helpful discussions.

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Authors

Contributions

S.A.I., Y.L. and Q.L. performed the multiscale simulations and developed the MKM. S.M. and Y.S. conducted catalyst synthesis, characterization and ammonia decomposition experiments. C.M. and J.Y. developed machine learning models. M.H.B. carried out the TEA and helped to analyze the data. Y.Y. directed the experimental validation project and assisted with analysis of both the experimental and theoretical data. F.C. developed the idea of the project, supervised the study, contributed to theory and machine learning model development, helped to analyze both the theoretical and experimental data, and managed the project. All authors contributed to writing and editing the paper.

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Correspondence to Yanhui Yi or Fanglin Che.

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Extended data

Extended Data Fig. 1 Machine learning model and screening workflow for bimetallic surface design.

(a) Schematic of the Random Forest (RF) model to predict EN, utilizing d-band information and solid-state properties of bimetallic surfaces. Key features include d-band descriptors (filling, center, width, skewness, and kurtosis up to the Fermi level), local Pauling electronegativity (reflecting delocalized sp-states), and metal-specific physical constants (spatial extent of d-orbitals, squared adsorbate-metal d coupling matrix element, work function, atomic radius, ionization potential, electron affinity, and Pauling electronegativity). (b) Screening workflow used to evaluate over 3,300 bimetallic alloy compositions based on ML-predicted d-band fillings and nitrogen adsorption energy.

Supplementary information

Supplementary Information

Supplementary Figs. 1–43, Tables 1–38 and Notes 1–10.

Supplementary Data 1

Atomic coordinates of all the DFT models.

Supplementary Code 2

Python scripts and input files for machine learning-based screening and MKM.

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Ahmat Ibrahim, S., Meng, S., Milhans, C. et al. Interpretable machine learning-guided plasma catalysis for hydrogen production. Nat Chem Eng 2, 699–710 (2025). https://doi.org/10.1038/s44286-025-00287-7

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