Rational Design of Highly Efficient Perovskite Hydroxide for Electrocatalytic Water Oxidation (original) (raw)
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High activity and durability of novel perovskite electrocatalysts for water oxidation
Development of highly active and cost-effective electrocatalysts is central to the large-scale electrolysis of water for renewable energy generation. Perovskite oxides are a group of promising candidates to lower the oxygen evolution reaction (OER) barriers in water splitting and further improvement of their activity and durability is an important objective. Here we report scandium and niobium cation (Sc3+ and Nb5+) doped strontium cobaltite perovskites (SrScxNbyCo1-x-yO3-δ) as a family of highly active and durable electrocatalysts for the OER in alkaline solution. These perovskites not only manifest up to a factor of 50 increase of the intrinsic activity compared to the gold-standard OER electrocatalysts (such as IrO2 and RuO2) and a factor of 5.8 enhancement to the perovskite-Ba0.5Sr0.5Co0.8Fe0.2O3-δ at overpotential of 0.35 V, but also, more importantly, show excellent durability in alkaline solutions under operation.
Catalysis Today, 2012
Perovskite oxides are promising materials for the ORR in alkaline media. However, catalytic layers prepared from perovskite powders suffer from high Ohmic losses and low catalyst utilization. An addition of carbon to the catalytic layers greatly improves the performance of the electrodes in the ORR. In this work composite thin film electrodes comprised of a perovskite oxide (either LaCoO 3 or La 0.8 Sr 0.2 MnO 3 ) and pyrolytic carbon of the Sibunit family were investigated in aqueous 1 M NaOH electrolyte using cyclic voltammetry and rotating disc electrode (RDE) method with the objective to unveil the influence of carbon on the catalyst utilization and on the ORR electrocatalysis. By systematically varying the oxide to carbon ratio we arrive to the conclusion on the dual role of carbon in composite electrodes. On the one hand, it is required to improve the electrical contact between perovskite particles and the current collector, and to ensure maximum utilization of the perovskite surface. On the other hand, carbon plays an active role in the ORR by catalyzing the O 2 reduction to H 2 O 2 . Composite electrodes catalyze the 4e − ORR in contrast to carbon which is only capable of catalyzing the 2e − reduction. For LaCoO 3 composite electrodes, carbon is responsible for the catalysis of the first steps of the ORR, the role of LaCoO 3 being largely limited to the hydrogen peroxide decomposition and/or reduction. For La 0.8 Sr 0.2 MnO 3 composite electrodes, along with the catalysis of the chemical decomposition and/or reduction of H 2 O 2 produced on carbon, the perovskite also significantly contributes to the first steps of the ORR. The results of this work suggest that the ORR on the carbon and the oxide components of composite cathodes must be considered as coupled reactions whose contributions cannot be always separated, and that neglecting the contribution of carbon to the ORR electrocatalysis may lead to erroneous values of the catalytic activity of perovskite materials.
Catalysts, 2020
The selection and evaluation of electrocatalysts as candidate materials for industrial alkaline water electrolysis is fundamental in the development of promising energy storage and sustainable fuels for future energy infrastructure. However, the oxygen evolution reaction (OER) activities of various electrocatalysts already reported in previous studies are not standardized. This work reports on the use of perovskite materials (LaFeO3, LaCoO3, LaNiO3, PrCoO3, Pr0.8Sr0.2CoO3, and Pr0.8Ba0.2CoO3) as OER electrocatalysts for alkaline water electrolysis. A facile co-precipitation technique with subsequent thermal annealing (at 700 °C in air) was performed. Industrial requirements and criteria (cost and ease of scaling up) were well-considered for the selection of the materials. The highest OER activity was observed in LaNiO3 among the La-based perovskites, and in Pr0.8Sr0.2CoO3 among the Pr-based perovskites. Moreover, the formation of double perovskites (Pr0.8Sr0.2CoO3 and Pr0.8Ba0.2CoO3...
Bifunctional Perovskite Oxide Catalysts for Oxygen Reduction and Evolution in Alkaline Media
Chemistry, an Asian journal, 2015
Oxygen electrocatalysis, namely of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), governs the performance of numerous electrochemical energy systems such as reversible fuel cells, metal-air batteries, and water electrolyzers. However, the sluggish kinetics of these two reactions and their dependency on expensive noble metal catalysts (e.g,, Pt or Ir) prohibit the sustainable commercialization of these highly innovative and in-demand technologies. Bi-functional perovskite oxides have emerged as a new class of highly efficient non-precious metal catalysts (NPMC) for oxygen electrocatalysis in alkaline media. In this review, we discuss the state-of-the-art understanding of bifunctional properties of perovskites with regards to their OER/ORR activity in alkaline media, review the associated reaction mechanisms on the oxides surface and the related activity descriptors developed in recent literature. We also summarize the present strategies to modify their elect...
The cost-effective production of green hydrogen is one of the most important challenges for a sustainable energy transition. To decrease the cost in the production of hydrogen through electrolysis, there are several obstacles that must be overcome. For instance, more active and stable anodes made of abundant and cheap materials will contribute to lowering the capital and operational expenditure of the process. It is well-known that the oxidation of water requires high overpotentials, which is the main limitation for the performance of the device. In this context, we believe that substituting the oxidation of water (OER) at the anode of electrolyzers by the oxidation of biomass-derived substances could contribute to the overall process by decreasing the power input of the devices and, in some cases, by producing value-added chemicals. Herein, we re-visited some of the most important fundamental aspects of the (electro-)oxidation of alcohols and polyols on metal-based catalysts, focus...
Perovskite oxides: Oxygen electrocatalysis and bulk structure
1987
Perovskite type oxides were considered for use as oxygen reduction and generation electrocatalysts in alkaline electrolytes. Perovskite stability and electrocatalytic activity are studied along with possible relationships of the latter with the bulk solid state properties. A series of compounds of the type LaFe(x)Ni1(-x)O3 was used as a model system to gain information on the possible relationships between surface catalytic