Stabilizing Highly Active Ru Sites by Electron Reservoir in Acidic Oxygen Evolution
Proton exchange membrane water electrolysis is hindered by the sluggish kinetics of the anodic oxygen evolution reaction. RuO<sub>2</sub> is regarded as a promising alternative to IrO<sub>2</sub> for the anode catalyst of proton exchange membrane water electrolyzers due to it...
| Main Authors: | , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2024-02-01
|
| Series: | Molecules |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1420-3049/29/4/785 |
| _version_ | 1797297390825242624 |
|---|---|
| author | Jiayan Wu Zhongjie Qiu Jiaxi Zhang Huiyu Song Zhiming Cui Li Du |
| author_facet | Jiayan Wu Zhongjie Qiu Jiaxi Zhang Huiyu Song Zhiming Cui Li Du |
| author_sort | Jiayan Wu |
| collection | DOAJ |
| description | Proton exchange membrane water electrolysis is hindered by the sluggish kinetics of the anodic oxygen evolution reaction. RuO<sub>2</sub> is regarded as a promising alternative to IrO<sub>2</sub> for the anode catalyst of proton exchange membrane water electrolyzers due to its superior activity and relatively lower cost compared to IrO<sub>2</sub>. However, the dissolution of Ru induced by its overoxidation under acidic oxygen evolution reaction (OER) conditions greatly hinders its durability. Herein, we developed a strategy for stabilizing RuO<sub>2</sub> in acidic OER by the incorporation of high-valence metals with suitable ionic electronegativity. A molten salt method was employed to synthesize a series of high-valence metal-substituted RuO<sub>2</sub> with large specific surface areas. The experimental results revealed that a high content of surface Ru<sup>4+</sup> species promoted the OER intrinsic activity of high-valence doped RuO<sub>2</sub>. It was found that there was a linear relationship between the ratio of surface Ru<sup>4+</sup>/Ru<sup>3+</sup> species and the ionic electronegativity of the dopant metals. By regulating the ratio of surface Ru<sup>4+</sup>/Ru<sup>3+</sup> species, incorporating Re, with the highest ionic electronegativity, endowed Re<sub>0.1</sub>Ru<sub>0.9</sub>O<sub>2</sub> with exceptional OER activity, exhibiting a low overpotential of 199 mV to reach 10 mA cm<sup>−2</sup>. More importantly, Re<sub>0.1</sub>Ru<sub>0.9</sub>O<sub>2</sub> demonstrated outstanding stability at both 10 mA cm<sup>−2</sup> (over 300 h) and 100 mA cm<sup>−2</sup> (over 25 h). The characterization of post-stability Re<sub>0.1</sub>Ru<sub>0.9</sub>O<sub>2</sub> revealed that Re promoted electron transfer to Ru, serving as an electron reservoir to mitigate excessive oxidation of Ru sites during the OER process and thus enhancing OER stability. We conclude that Re, with the highest ionic electronegativity, attracted a mass of electrons from Ru in the pre-catalyst and replenished electrons to Ru under the operating potential. This work spotlights an effective strategy for stabilizing cost-effective Ru-based catalysts for acidic OER. |
| first_indexed | 2024-03-07T22:19:37Z |
| format | Article |
| id | doaj.art-33d37b7583dc4b6fba81ff4116ded645 |
| institution | Directory Open Access Journal |
| issn | 1420-3049 |
| language | English |
| last_indexed | 2024-03-07T22:19:37Z |
| publishDate | 2024-02-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Molecules |
| spelling | doaj.art-33d37b7583dc4b6fba81ff4116ded6452024-02-23T15:28:52ZengMDPI AGMolecules1420-30492024-02-0129478510.3390/molecules29040785Stabilizing Highly Active Ru Sites by Electron Reservoir in Acidic Oxygen EvolutionJiayan Wu0Zhongjie Qiu1Jiaxi Zhang2Huiyu Song3Zhiming Cui4Li Du5Guangdong Provincial Key Laboratory of Fuel Cell Technology, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641, ChinaGuangdong Provincial Key Laboratory of Fuel Cell Technology, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641, ChinaGuangdong Provincial Key Laboratory of Fuel Cell Technology, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641, ChinaGuangdong Provincial Key Laboratory of Fuel Cell Technology, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641, ChinaGuangdong Provincial Key Laboratory of Fuel Cell Technology, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641, ChinaGuangdong Provincial Key Laboratory of Fuel Cell Technology, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641, ChinaProton exchange membrane water electrolysis is hindered by the sluggish kinetics of the anodic oxygen evolution reaction. RuO<sub>2</sub> is regarded as a promising alternative to IrO<sub>2</sub> for the anode catalyst of proton exchange membrane water electrolyzers due to its superior activity and relatively lower cost compared to IrO<sub>2</sub>. However, the dissolution of Ru induced by its overoxidation under acidic oxygen evolution reaction (OER) conditions greatly hinders its durability. Herein, we developed a strategy for stabilizing RuO<sub>2</sub> in acidic OER by the incorporation of high-valence metals with suitable ionic electronegativity. A molten salt method was employed to synthesize a series of high-valence metal-substituted RuO<sub>2</sub> with large specific surface areas. The experimental results revealed that a high content of surface Ru<sup>4+</sup> species promoted the OER intrinsic activity of high-valence doped RuO<sub>2</sub>. It was found that there was a linear relationship between the ratio of surface Ru<sup>4+</sup>/Ru<sup>3+</sup> species and the ionic electronegativity of the dopant metals. By regulating the ratio of surface Ru<sup>4+</sup>/Ru<sup>3+</sup> species, incorporating Re, with the highest ionic electronegativity, endowed Re<sub>0.1</sub>Ru<sub>0.9</sub>O<sub>2</sub> with exceptional OER activity, exhibiting a low overpotential of 199 mV to reach 10 mA cm<sup>−2</sup>. More importantly, Re<sub>0.1</sub>Ru<sub>0.9</sub>O<sub>2</sub> demonstrated outstanding stability at both 10 mA cm<sup>−2</sup> (over 300 h) and 100 mA cm<sup>−2</sup> (over 25 h). The characterization of post-stability Re<sub>0.1</sub>Ru<sub>0.9</sub>O<sub>2</sub> revealed that Re promoted electron transfer to Ru, serving as an electron reservoir to mitigate excessive oxidation of Ru sites during the OER process and thus enhancing OER stability. We conclude that Re, with the highest ionic electronegativity, attracted a mass of electrons from Ru in the pre-catalyst and replenished electrons to Ru under the operating potential. This work spotlights an effective strategy for stabilizing cost-effective Ru-based catalysts for acidic OER.https://www.mdpi.com/1420-3049/29/4/785high-valence metalionic electronegativitystabilized RuO<sub>2</sub>acidic oxygen evolution reaction |
| spellingShingle | Jiayan Wu Zhongjie Qiu Jiaxi Zhang Huiyu Song Zhiming Cui Li Du Stabilizing Highly Active Ru Sites by Electron Reservoir in Acidic Oxygen Evolution Molecules high-valence metal ionic electronegativity stabilized RuO<sub>2</sub> acidic oxygen evolution reaction |
| title | Stabilizing Highly Active Ru Sites by Electron Reservoir in Acidic Oxygen Evolution |
| title_full | Stabilizing Highly Active Ru Sites by Electron Reservoir in Acidic Oxygen Evolution |
| title_fullStr | Stabilizing Highly Active Ru Sites by Electron Reservoir in Acidic Oxygen Evolution |
| title_full_unstemmed | Stabilizing Highly Active Ru Sites by Electron Reservoir in Acidic Oxygen Evolution |
| title_short | Stabilizing Highly Active Ru Sites by Electron Reservoir in Acidic Oxygen Evolution |
| title_sort | stabilizing highly active ru sites by electron reservoir in acidic oxygen evolution |
| topic | high-valence metal ionic electronegativity stabilized RuO<sub>2</sub> acidic oxygen evolution reaction |
| url | https://www.mdpi.com/1420-3049/29/4/785 |
| work_keys_str_mv | AT jiayanwu stabilizinghighlyactiverusitesbyelectronreservoirinacidicoxygenevolution AT zhongjieqiu stabilizinghighlyactiverusitesbyelectronreservoirinacidicoxygenevolution AT jiaxizhang stabilizinghighlyactiverusitesbyelectronreservoirinacidicoxygenevolution AT huiyusong stabilizinghighlyactiverusitesbyelectronreservoirinacidicoxygenevolution AT zhimingcui stabilizinghighlyactiverusitesbyelectronreservoirinacidicoxygenevolution AT lidu stabilizinghighlyactiverusitesbyelectronreservoirinacidicoxygenevolution |