Performance of All-Solid-State MoO<sub>x</sub> pH Sensors Prepared via Thermal Oxidation for Robust Applications
In this study, we investigated the morphology, chemical composition and pH measurement performance of MoO<sub>x</sub> electrodes prepared via thermal oxidation and submitted to hydration in milliQ water. Surface analysis using SEM-EDS and XPS revealed that the hydrated MoO<sub>x<...
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| Format: | Article |
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MDPI AG
2025-01-01
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| Series: | Sensors |
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| Online Access: | https://www.mdpi.com/1424-8220/25/3/611 |
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| author | Djouhar Aoubida Stephanie Betelu Johan Bertrand Quoc Nghi Pham Diana Dragoe Nita Dragoe Ioannis Ignatiadis |
| author_facet | Djouhar Aoubida Stephanie Betelu Johan Bertrand Quoc Nghi Pham Diana Dragoe Nita Dragoe Ioannis Ignatiadis |
| author_sort | Djouhar Aoubida |
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| description | In this study, we investigated the morphology, chemical composition and pH measurement performance of MoO<sub>x</sub> electrodes prepared via thermal oxidation and submitted to hydration in milliQ water. Surface analysis using SEM-EDS and XPS revealed that the hydrated MoO<sub>x</sub> film is composed of different oxidation states of Mo (Mo (IV), Mo (V) and Mo (VI)), influencing its electrochemical behavior. A hydration period of 45 days was required for the electrode to achieve a response approaching the Nernstian model (−58 mV/pH), while extended hydration of up to 70 days enhanced its stability and sensitivity. The electrode’s performance was assessed under various conditions, including in the presence and absence of oxygen and in anaerobic conditions with the presence of sulfides. Oxygen absence increased sensitivity and lowered the experimental standard potential (E<sup>0</sup><sub>Exp</sub>) due to the effect of oxygen vacancies. Low sulfide concentrations had minimal impact on electrode performance, although higher concentrations may slightly decrease the electron transfer efficiency due to the complex formation. The pH sensing mechanisms of MoO<sub>x</sub> electrodes are also discussed. |
| format | Article |
| id | doaj-art-83252beff4aa46f693844f6450c0b433 |
| institution | OA Journals |
| issn | 1424-8220 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Sensors |
| spelling | doaj-art-83252beff4aa46f693844f6450c0b4332025-08-20T02:12:29ZengMDPI AGSensors1424-82202025-01-0125361110.3390/s25030611Performance of All-Solid-State MoO<sub>x</sub> pH Sensors Prepared via Thermal Oxidation for Robust ApplicationsDjouhar Aoubida0Stephanie Betelu1Johan Bertrand2Quoc Nghi Pham3Diana Dragoe4Nita Dragoe5Ioannis Ignatiadis6BRGM (French Geological Survey), 45060 Orleans, FranceBRGM (French Geological Survey), 45060 Orleans, FranceANDRA (French National Radioactive Waste Management Agency), 92298 Châtenay-Malabry, FranceICMMO (Institute of Molecular Chemistry and Materials), 91400 Orsay, FranceICMMO (Institute of Molecular Chemistry and Materials), 91400 Orsay, FranceICMMO (Institute of Molecular Chemistry and Materials), 91400 Orsay, FranceBRGM (French Geological Survey), 45060 Orleans, FranceIn this study, we investigated the morphology, chemical composition and pH measurement performance of MoO<sub>x</sub> electrodes prepared via thermal oxidation and submitted to hydration in milliQ water. Surface analysis using SEM-EDS and XPS revealed that the hydrated MoO<sub>x</sub> film is composed of different oxidation states of Mo (Mo (IV), Mo (V) and Mo (VI)), influencing its electrochemical behavior. A hydration period of 45 days was required for the electrode to achieve a response approaching the Nernstian model (−58 mV/pH), while extended hydration of up to 70 days enhanced its stability and sensitivity. The electrode’s performance was assessed under various conditions, including in the presence and absence of oxygen and in anaerobic conditions with the presence of sulfides. Oxygen absence increased sensitivity and lowered the experimental standard potential (E<sup>0</sup><sub>Exp</sub>) due to the effect of oxygen vacancies. Low sulfide concentrations had minimal impact on electrode performance, although higher concentrations may slightly decrease the electron transfer efficiency due to the complex formation. The pH sensing mechanisms of MoO<sub>x</sub> electrodes are also discussed.https://www.mdpi.com/1424-8220/25/3/611all-solid-state electrodespH sensorredox potentialnuclear wastegeological disposal monitoringthermal oxidation |
| spellingShingle | Djouhar Aoubida Stephanie Betelu Johan Bertrand Quoc Nghi Pham Diana Dragoe Nita Dragoe Ioannis Ignatiadis Performance of All-Solid-State MoO<sub>x</sub> pH Sensors Prepared via Thermal Oxidation for Robust Applications Sensors all-solid-state electrodes pH sensor redox potential nuclear waste geological disposal monitoring thermal oxidation |
| title | Performance of All-Solid-State MoO<sub>x</sub> pH Sensors Prepared via Thermal Oxidation for Robust Applications |
| title_full | Performance of All-Solid-State MoO<sub>x</sub> pH Sensors Prepared via Thermal Oxidation for Robust Applications |
| title_fullStr | Performance of All-Solid-State MoO<sub>x</sub> pH Sensors Prepared via Thermal Oxidation for Robust Applications |
| title_full_unstemmed | Performance of All-Solid-State MoO<sub>x</sub> pH Sensors Prepared via Thermal Oxidation for Robust Applications |
| title_short | Performance of All-Solid-State MoO<sub>x</sub> pH Sensors Prepared via Thermal Oxidation for Robust Applications |
| title_sort | performance of all solid state moo sub x sub ph sensors prepared via thermal oxidation for robust applications |
| topic | all-solid-state electrodes pH sensor redox potential nuclear waste geological disposal monitoring thermal oxidation |
| url | https://www.mdpi.com/1424-8220/25/3/611 |
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