| 1. |
- Stoerzinger, Kelsey A., et al.
(författare)
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Orientation-Dependent Oxygen Evolution on RuO2 without Lattice Exchange
- 2017
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Ingår i: ACS Energy Letters. - : American Chemical Society (ACS). - 2380-8195. ; 2:4, s. 876-881
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Tidskriftsartikel (refereegranskat)abstract
- RuO2 catalysts exhibit record activities toward the oxygen evolution reaction (OER), which is crucial to enable efficient and sustainable energy storage. Here we examine the RuO2 OER kinetics on rutile (110), (100), (101), and (111) orientations, finding (100) the most active. We assess the potential involvement of lattice oxygen in the OER mechanism with online electrochemical mass spectrometry, which showed no evidence of oxygen exchange on these oriented facets in acidic or basic electrolytes. Similar results were obtained for polyoriented RuO2 films and particles, in contrast to previous work, suggesting lattice oxygen is not exchanged in catalyzing OER on crystalline RuO2 surfaces. This hypothesis is supported by the correlation of activity with the number of active Ru-sites calculated by density functional theory, where more active facets bind oxygen more weakly. This new understanding of the active sites provides a design strategy to enhance the OER activity of RuO2 nanoparticles by facet engineering.
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| 2. |
- Han, Binghong, et al.
(författare)
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Iron-Based Perovskites for Catalyzing Oxygen Evolution Reaction
- 2018
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 122:15, s. 8445-8454
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Tidskriftsartikel (refereegranskat)abstract
- The slow kinetics of the oxygen evolution reaction (OER) is the main cause of energy loss in many low temperature energy storage techniques, such as metal air batteries and water splitting. A better understanding of both the OER mechanism and the degradation mechanism on different transition metal (TM) oxides is critical for the development of the, next generation of oxides as OER catalysts. In this paper, we systematically investigated the catalytic mechanism and lifetime of ABO(3-delta) perovskite catalysts for the OER, where A = Sr or Ca and B = Fe or Co. During the OER process, the Fe-based AFeO(3-delta) oxides with (delta approximate to 0.5 demonstrate no activation of lattice oxygen or pH dependence of the OER activity, which is different from the SrCoO25 with similar oxygen 2p-band position relative to the Fermi level. The difference was attributed to the larger changes in the electronic structure during the transition from the oxygen-deficient brownmillerite structure to the fully oxidized perovskite structure and the poor conductivity in Fe-based oxides, which hinders the uptake of oxygen from the electrolyte to the lattice under oxidative potentials. The low stability of Fe-based perovskites under OER conditions in a basic electrolyte also contributes to the different OER mechanism compared with the Co-based perovskites. This work reveals the influence of TM composition and electronic structure on the catalytic mechanism and operational stability of the perovskite OER catalysts.
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