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Optimization of Active Sites via Crystal Phase, Composition, and Morphology for Efficient Low-Iridium Oxygen Evolution Catalysts.
Angewandte Chemie International Edition ( IF 16.1 ) Pub Date : 2020-06-02 , DOI: 10.1002/anie.202006756
Hui Chen 1 , Lei Shi 1 , Xiao Liang 1 , Lina Wang 1 , Tewodros Asefa 2 , Xiaoxin Zou 1
Affiliation  

Reducing the amount of iridium in oxygen evolution electrocatalysts without compromising their catalytic performances is one of the major requirements in proton‐exchange‐membrane water electrolyzers. Herein, with the help of theoretical studies, we show that anatase‐type TiO2‐IrO2 solid solutions possess more active iridium catalytic sites for the oxygen evolution reaction (OER) than IrO2, the benchmark OER catalyst. Note that the same is not observed for their rutile‐type counterparts. However, owing to their thermodynamic metastability, anatase‐type TiO2‐IrO2 solid solutions are generally hard to synthesize. Our theoretical studies demonstrate that such catalytically active anatase‐type solid‐solution phases can be created in situ on the surfaces of readily available SrTiO3‐SrIrO3 solid solutions during electrocatalysis in acidic solution as the solution can etch away Sr atoms. We experimentally show this with porous SrTiO3‐SrIrO3 solid‐solution nanotubes synthesized by a facile synthetic route that contain 56 % less iridium than IrO2 yet show an order of magnitude higher apparent catalytic activity for OER in acidic solution.

中文翻译:

通过结晶相,组成和形态优化活性位点,以制备高效的低铱氧气析出催化剂。

在质子交换膜水电解槽中,减少氧气逸出电催化剂中的铱量而不损害其催化性能是主要要求之一。在本文中,借助理论研究,我们证明了锐钛矿型TiO 2 ‐IrO 2固溶体比标准OER催化剂IrO 2具有更多的活性氧催化放氧反应(OER)的铱催化位。请注意,对于金红石型对应物,未观察到相同的情况。然而,由于其热力学亚稳定性,锐钛矿型TiO 2 -IrO 2固溶体通常难以合成。我们的理论研究表明,在酸性溶液中进行电催化时,由于溶液可以腐蚀掉Sr原子,因此可以在易于获得的SrTiO 3 -SrIrO 3固溶体的表面上原位生成此类具有催化活性的锐钛矿型固溶相。我们通过实验证明,通过一种简便的合成路线合成的多孔SrTiO 3 -SrIrO 3固溶纳米管,其铱含量比IrO 2少56%,但在酸性溶液中对OER的表观催化活性更高。
更新日期:2020-06-02
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