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Active and durable R₂MnRuO₇ pyrochlores with low Ru content for acidic oxygen evolution.

ABSTRACT: The production of green hydrogen in water electrolyzers is limited by the oxygen evolution reaction (OER). State-of-the-art electrocatalysts are based on Ir. Ru electrocatalysts are a suitable alternative provided their performance is improved. Here we show that low-Ru-content pyrochlores (R₂MnRuO₇, R = Y, Tb and Dy) display high activity and durability for the OER in acidic media. Y₂MnRuO₇ is the most stable catalyst, displaying 1.5 V at 10 mA cm^-2 for 40 h, or 5000 cycles up to 1.7 V. Computational and experimental results show that the high performance is owed to Ru sites embedded in RuMnO_x surface layers. A water electrolyser with Y₂MnRuO₇ (with only 0.2 mg_Ru cm^-2) reaches 1 A cm^-2 at 1.75 V, remaining stable at 200 mA cm^-2 for more than 24 h. These results encourage further investigation on Ru catalysts in which a partial replacement of Ru by inexpensive cations can enhance the OER performance.

SUBMITTER: Galyamin D

PROVIDER: S-EPMC10086044 | biostudies-literature | 2023 Apr

REPOSITORIES: biostudies-literature

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Active and durable R2MnRuO7 pyrochlores with low Ru content for acidic oxygen evolution.

Galyamin Dmitry D Torrero Jorge J Rodríguez Isabel I Kolb Manuel J MJ Ferrer Pilar P Pascual Laura L Salam Mohamed Abdel MA Gianolio Diego D Celorrio Verónica V Mokhtar Mohamed M Garcia Sanchez Daniel D Gago Aldo Saul AS Friedrich Kaspar Andreas KA Peña Miguel A MA Alonso José Antonio JA Calle-Vallejo Federico F Retuerto María M Rojas Sergio S

Nature communications 20230410 1

The production of green hydrogen in water electrolyzers is limited by the oxygen evolution reaction (OER). State-of-the-art electrocatalysts are based on Ir. Ru electrocatalysts are a suitable alternative provided their performance is improved. Here we show that low-Ru-content pyrochlores (R2MnRuO7, R = Y, Tb and Dy) display high activity and durability for the OER in acidic media. Y2MnRuO7 is the most stable catalyst, displaying 1.5 V at 10 mA cm ...[more]

PMID: 37037807

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Project description:Improved oxygen evolution reaction (OER) electrocatalysts based on an additional understanding of surface changes that occur upon metal dissolution are needed to enable the efficient use of electrochemical water splitting. This work integrates theoretical and experimental studies of the effects of metal dissolution from the RuO2 and Ru1-x Ti x O2 surfaces on the OER activity and electrochemical stability. Our computational analysis shows that the energetic barriers for metal dissolution depend highly on the surface site and Ti-substituent location. Metal dissolution induces the formation of new active surface sites with different electronic density distributions. In addition to dissolution-induced changes to the surface composition, electron density changes occur in the interfacial electrolyte components. Surface reconstruction changes the activation barriers for the OER steps. Our experimental analysis of RuO2 and Ru0.8Ti0.2O2 using a two-step durability test in acidic electrolytes shows that the OER activity, surface, and metal dissolution change over the durability tests. Ti-substitution exhibits improved electrochemical stability with cycling. For RuO2, changes in the mass activity of RuO2 with cycling are directly correlated with Ru dissolution and lowering of the electrochemical surface area (ECSA). In contrast, Ru0.8Ti0.2O2 showed a 19 times lower Ru dissolution rate, and metal dissolution results in increasing the ECSA and new active sites. Our STEM and EELS analysis supports that repeated cycling under OER conditions results in surface reconstruction for both RuO2 and Ru0.8Ti0.2O2, with the formation of a disordered RuO2 surface and changes to the distribution of Ru and Ti at the Ru0.8Ti0.2O2 surface. The experimentally observed changes in activity and surface structure after cycling are consistent with computational analysis, which shows how metal dissolution may alter the OER activation barriers. Combining experimental and computational insights, this work reveals the effects of metal dissolution on the surface atomic and electronic structure and OER activity and advances our comprehension of metal dissolution dynamics and surface reconstruction, which may have implications for other catalytic processes.

Dataset Information

Active and durable R₂MnRuO₇ pyrochlores with low Ru content for acidic oxygen evolution.

Publications

Active and durable R<sub>2</sub>MnRuO<sub>7</sub> pyrochlores with low Ru content for acidic oxygen evolution.

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