X射线光电子能谱
材料科学
催化作用
析氧
兴奋剂
氧化物
电催化剂
化学工程
微晶
色散(光学)
纳米颗粒
纳米技术
电化学
电极
化学
物理化学
冶金
光电子学
生物化学
物理
光学
工程类
作者
Radostina V. Genova-Koleva,Francisco Alcaide,Garbiñe Álvarez,Pere Lluı́s Cabot,Hans‐Jürgen Grande,M.V. Martı́nez-Huerta,Óscar Miguel
标识
DOI:10.1016/j.jechem.2019.03.008
摘要
IrO2 and IrRuOx (Ir:Ru 60:40 at%), supported by 50 wt% onto titania nanotubes (TNTs) and (3 at% Nb) Nb-doped titania nanotubes (Nb-TNTs), as electrocatalysts for the oxygen evolution reaction (OER), were synthesized and characterized by means of structural, surface analytical and electrochemical techniques. Nb doping of titania significantly increased the surface area of the support from 145 (TNTs) to 260 m2 g−1 (Nb-TNTs), which was significantly higher than those of the Nb-doped titania supports previously reported in the literature. The surface analytical techniques showed good dispersion of the catalysts onto the supports. The X-ray photoelectron spectroscopy analyses showed that Nb was mainly in the form of Nb(IV) species, the suitable form to behave as a donor introducing free electrons to the conduction band of titania. The redox transitions of the cyclic voltammograms, in agreement with the XPS results, were found to be reversible. Despite the supported materials presented bigger crystallite sizes than the unsupported ones, the total number of active sites of the former was also higher due to their better catalyst dispersion. Considering the outer and the total charges of the cyclic voltammograms in the range 0.1–1.4 V, stability and electrode potentials at given current densities, the preferred catalyst was IrO2 supported on the Nb-TNTs. The electrode potentials corresponding to given current densities were between the smallest ones given in the literature despite the small oxide loading used in this work and its Nb doping, thus making the Nb-TNTs-supported IrO2 catalyst a promising candidate for the OER. The good dispersion of IrO2, high specific surface area of the Nb-doped supports, accessibility of the electroactive centers, increased stability due to Nb doping and electron donor properties of the Nb(IV) oxide species were considered the main reasons for its good performance.
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