| Title: |
Carbon-induced metal growth and size-dependent activity in methane splitting on nickel nanoparticle catalysts for COx-free hydrogen production |
| Authors: |
Atashi, Niloufar; Palomares-Ferrando, Adrià; Prieto González, Gonzalo; Verziaggi, Nicola; Alves, Luis; Mendes, Adélio; Meloni, Simone |
| Contributors: |
Instituto Universitario Mixto de Tecnología Química; European Commission; Generalitat Valenciana; Agencia Estatal de Investigación; Consejo Superior de Investigaciones Científicas; Universitat Politècnica de València |
| Publisher Information: |
Elsevier |
| Publication Year: |
2026 |
| Collection: |
Universitat Politécnica de Valencia: RiuNet / Politechnical University of Valencia |
| Subject Terms: |
Methane decomposition; Turquoise hydrogen; Carbon-assisted particle growth; Operando XRD; Density functional theory |
| Description: |
[EN] Catalytic methane splitting (CMS) to hydrogen and elemental carbon is a promising route to produce COx-free hydrogen, potentially achieving net carbon-negative output when using biogenic methane as the feedstock. On transition metal nanocrystals, especially Ni, CMS proceeds at lower temperatures ( 1000 K) compared to (plasma-assisted) methane pyrolysis, additionally leading to higher added-value graphitic carbon nanostructure products. Earlier work has indicated that the size of the metal nanocrystals plays a central role for hydrogen (and carbon) production rates, however, conflicting results have been reported, possibly as a result of challenges associated to the deposition of the carbon products on the catalyst surface as well as phenomena like metal particle growth, fragmentation and deactivation. Herein metal nanocrystal size effects are assessed on the methane splitting reaction rate with a series of model supported Ni catalysts. A maximum methane splitting rate is attained for Ni nanoparticles with a diameter of similar to 10 nm at the onset of the reaction. Operando synchrotron X-ray diffraction and activity-specific transmission electron microscopy studies attribute the observed size effects on reaction rate to differences in the relative contribution of Ni nanocrystals larger and smaller than ca. 10 nm. This metal nanoparticle diameter represents a threshold minimum size for the effective nucleation and growth of graphitic carbon filaments, and therefore for sustained hydrogen production, which entails the lifting of Ni nanocrystals away from the oxide support in a carbon tip-growth mechanism. Moreover, operando studies reveal metal nanocrystal growth, which is specifically driven by the earliest methane splitting events on the catalyst surface, and determinant for the metal aggregation extent and intrinsic activity of the actual working catalyst. Density Functional Theory analyses identify *C and *CH3 adspecies, emerging from CH4 splitting on neat Ni surfaces, as central mediators to attain ... |
| Document Type: |
article in journal/newspaper |
| File Description: |
application/pdf |
| Language: |
English |
| Relation: |
Applied Catalysis B Environmental; info:eu-repo/grantAgreement/AEI/Plan Estatal de Investigación Científica y Técnica y de Innovación 2021-2023/PID2022-140111OB-I00/ES/HACIA EL GREEN DEAL: SINERGIAS ENTRE CATALISIS HETEROGENEA Y HOMOGENEA PARA LA PRODUCCION SELECTIVA DE COMPUESTOS QUIMICOS ORGANOALQUILO DESDE FUENTES C1 RENOVA/; info:eu-repo/grantAgreement/EC/H2020/952219/EU/Low temperature catalytic methane decomposition for COx-free hydrogen production/; info:eu-repo/grantAgreement/CSIC//JAEINT_22_EX_0795/; info:eu-repo/grantAgreement/GVA//MFA%2F2022%2F012/; info:eu-repo/grantAgreement/AEI//CEX2021-001230-S/; https://doi.org/10.1016/j.apcatb.2025.125817; https://riunet.upv.es/handle/10251/229700 |
| DOI: |
10.1016/j.apcatb.2025.125817 |
| Availability: |
https://riunet.upv.es/handle/10251/229700; https://doi.org/10.1016/j.apcatb.2025.125817 |
| Rights: |
http://creativecommons.org/licenses/by-nc-nd/4.0/ ; info:eu-repo/semantics/openAccess |
| Accession Number: |
edsbas.2678904F |
| Database: |
BASE |