Chemical state analysis of size-controlled particles during redox reactions between NiO and metallic Ni
The chemical state change between NiO and Ni for size-controlled particles supported on SiO2 was analyzed by means of in situ X-ray absorption fine structure technique. The reduction of NiO particles by H2 gas occurred in two stages at approximately 380 °C and 650 °C, and the relative contribution o...
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Elsevier
2025-07-01
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| Series: | Next Materials |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2949822825002564 |
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| author | Eka Novitasari Asaka Azuma Kodai Ohta Misato Katayama Yasuhiro Niwa Masao Kimura Yasuhiro Inada |
| author_facet | Eka Novitasari Asaka Azuma Kodai Ohta Misato Katayama Yasuhiro Niwa Masao Kimura Yasuhiro Inada |
| author_sort | Eka Novitasari |
| collection | DOAJ |
| description | The chemical state change between NiO and Ni for size-controlled particles supported on SiO2 was analyzed by means of in situ X-ray absorption fine structure technique. The reduction of NiO particles by H2 gas occurred in two stages at approximately 380 °C and 650 °C, and the relative contribution of each stage varied with the particle size. Based on the particle size and the composition, it was interpreted that the NiO component, which was reduced at high temperatures, was stabilized by forming a silicate-like structure at the interface with SiO2. When metallic Ni particles were exposed to O2 gas at room temperature, NiO was produced in an amount dependent on the surface area calculated from the particle size, suggesting that a 0.5–0.9 nm surface layer of the Ni particles was oxidized to NiO. As the temperature increased, all remaining metallic Ni in the particle core was oxidized to NiO. The higher oxidation completion temperature in larger particles suggests that the NiO layer expanded inward from the surface. The NiO formed on the surface of the metallic Ni particles was reduced by heating up to 300 °C in an H2 gas atmosphere. This low reduction temperature indicates a high capacity of the surface NiO species for oxide ion dissociation, likely due to lattice mismatch with the internal metallic Ni. The redox processes between NiO and Ni generated an inhomogeneous distribution of chemical states within individual particles. |
| format | Article |
| id | doaj-art-bb3eb7f4de2a43c7919a08af2ef0a729 |
| institution | OA Journals |
| issn | 2949-8228 |
| language | English |
| publishDate | 2025-07-01 |
| publisher | Elsevier |
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| series | Next Materials |
| spelling | doaj-art-bb3eb7f4de2a43c7919a08af2ef0a7292025-08-20T01:55:37ZengElsevierNext Materials2949-82282025-07-01810073810.1016/j.nxmate.2025.100738Chemical state analysis of size-controlled particles during redox reactions between NiO and metallic NiEka Novitasari0Asaka Azuma1Kodai Ohta2Misato Katayama3Yasuhiro Niwa4Masao Kimura5Yasuhiro Inada6Graduate School of Life Sciences, Ritsumeikan University, Noji-Higashi 1-1-1, Kusatsu 525-8577, JapanGraduate School of Life Sciences, Ritsumeikan University, Noji-Higashi 1-1-1, Kusatsu 525-8577, JapanGraduate School of Life Sciences, Ritsumeikan University, Noji-Higashi 1-1-1, Kusatsu 525-8577, JapanGraduate School of Life Sciences, Ritsumeikan University, Noji-Higashi 1-1-1, Kusatsu 525-8577, JapanPhoton Factory, High Energy Accelerator Research Organization, Oho 1-1, Tsukuba 305-0801, JapanPhoton Factory, High Energy Accelerator Research Organization, Oho 1-1, Tsukuba 305-0801, JapanGraduate School of Life Sciences, Ritsumeikan University, Noji-Higashi 1-1-1, Kusatsu 525-8577, Japan; Corresponding author.The chemical state change between NiO and Ni for size-controlled particles supported on SiO2 was analyzed by means of in situ X-ray absorption fine structure technique. The reduction of NiO particles by H2 gas occurred in two stages at approximately 380 °C and 650 °C, and the relative contribution of each stage varied with the particle size. Based on the particle size and the composition, it was interpreted that the NiO component, which was reduced at high temperatures, was stabilized by forming a silicate-like structure at the interface with SiO2. When metallic Ni particles were exposed to O2 gas at room temperature, NiO was produced in an amount dependent on the surface area calculated from the particle size, suggesting that a 0.5–0.9 nm surface layer of the Ni particles was oxidized to NiO. As the temperature increased, all remaining metallic Ni in the particle core was oxidized to NiO. The higher oxidation completion temperature in larger particles suggests that the NiO layer expanded inward from the surface. The NiO formed on the surface of the metallic Ni particles was reduced by heating up to 300 °C in an H2 gas atmosphere. This low reduction temperature indicates a high capacity of the surface NiO species for oxide ion dissociation, likely due to lattice mismatch with the internal metallic Ni. The redox processes between NiO and Ni generated an inhomogeneous distribution of chemical states within individual particles.http://www.sciencedirect.com/science/article/pii/S2949822825002564Size-controlled Ni particlesRedox reactionIn situ XAFSInhomogeneous chemical state |
| spellingShingle | Eka Novitasari Asaka Azuma Kodai Ohta Misato Katayama Yasuhiro Niwa Masao Kimura Yasuhiro Inada Chemical state analysis of size-controlled particles during redox reactions between NiO and metallic Ni Next Materials Size-controlled Ni particles Redox reaction In situ XAFS Inhomogeneous chemical state |
| title | Chemical state analysis of size-controlled particles during redox reactions between NiO and metallic Ni |
| title_full | Chemical state analysis of size-controlled particles during redox reactions between NiO and metallic Ni |
| title_fullStr | Chemical state analysis of size-controlled particles during redox reactions between NiO and metallic Ni |
| title_full_unstemmed | Chemical state analysis of size-controlled particles during redox reactions between NiO and metallic Ni |
| title_short | Chemical state analysis of size-controlled particles during redox reactions between NiO and metallic Ni |
| title_sort | chemical state analysis of size controlled particles during redox reactions between nio and metallic ni |
| topic | Size-controlled Ni particles Redox reaction In situ XAFS Inhomogeneous chemical state |
| url | http://www.sciencedirect.com/science/article/pii/S2949822825002564 |
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