Probing adsorbates on La1−xSrxNiO3−δ surfaces under humid conditions: implications for the oxygen evolution reaction. (27th April 2021)

• Record Type: Journal Article
• Authors: Carvalho, O Quinn; Adiga, Prajwal; Wang, Le; Liu, Jishan; Jia, Endong; Du, Yingge; Nemšák, Slavomir; Stoerzinger, Kelsey A
• Is Part Of: Journal of physics. Volume 54:Number 27(2021)
• Publication Date: 2021-04-27
• Subjects: rare-earth nickelates -- ambient pressure-x-ray photoelectron spectroscopy -- water splitting -- metal–oxygen covalency; Physics -- Periodicals; 530
• DOI: 10.1088/1361-6463/abf674
• Languages: English
• ISSNs: 0022-3727

Abstract

Abstract: Earth-abundant nickel-containing perovskite oxides (ANiO3 ) are highly active materials for the oxygen evolution reaction (OER). The strong nickel-oxygen (Ni–O) covalency, tunable by A-site chemical substitution, contributes to both bulk and surface material properties like the formation of oxygen vacancies ( v O ) and OER activity. Here we quantify the coverage of OER relevant adsorbates on a series of La1− x Sr x NiO3− δ (LSNO, 0 ⩽ x ⩽ 0.5) epitaxial thin films exposed to humid environments by ambient pressure x-ray photoelectron spectroscopy. While all LSNO film compositions investigated here have comparable hydroxide coverages at the relative humidities (RHs) probed (1.5 × 10 −5 – 0.2%RH), the amount of under-coordinated surface oxygen increases notably with Sr content. We interpret differences in the free energy of adsorption (Δ G ads, i ) of these OER intermediates, inferred from adsorption isotherms, in the context of proposed v O -mediated OER mechanisms, consistent with the pH-dependent OER activity observed here for LSNO. We find that Sr incorporation enhances the affinity of LSNO surfaces for these under-coordinated oxygen species, in line with calculations in the literature.