Journal Article

PUBDB-2026-01523

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Active-species evolution dictates electrocatalytic performance and stability in alkaline earth nickelates for urea electrolysis

Rao, N. N.Extern* ; Alex, C. ; Seok, J. H. ; Kumar, A. A. ; Byun, J. S.Extern* ; Kovilakath, M. S. N. ; Lee, S. U. (Corresponding author)Extern* ; John, N. S. (Corresponding author)Extern*

2026
Elsevier Amsterdam

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Please use a persistent id in citations: doi:10.1016/j.apcatb.2026.126666

Abstract: Hybrid water electrolysis coupled with the urea electro-oxidation reaction (UOR) enables energy-efficient hydrogen generation while simultaneously treating urea-containing wastewater. Herein, we explore alkaline-earth metal nickelates - barium and strontium nickelates, for their ability to stabilize high oxidation states of Ni, which upon electrochemical activation readily form NiOOH, the active species for UOR. Interestingly, these nickelates distinctly evolve into γ- and β-NiOOH, dictated by the intrinsic chemical properties of the ‘parent’ nickelates. The dynamic formation and transformation of these species during operation are tracked using in situ Raman and X-ray absorption spectroscopy. Electrochemical impedance spectroscopy, long-term stability tests, and post-mortem analyses reveal pronounced differences in COx poison tolerance, active-site evolution, and overall stability. Calculations from the density functional theory attribute the observed trends to variations in hydroxylation tendency, carbonate-ion intercalation, and d-p orbital hybridization, thereby establishing a direct link between the structural attributes of the parent nickelates and the behaviour of the in situ - formed active species. This study thus establishes a direct structure-activity correlation linking the intrinsic chemistry of nickelates to phase-selective NiOOH formation and the resulting variations in electrocatalytic UOR performance.

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Contributing Institute(s):

1. FS DOOR-User (FS DOOR-User)

Research Program(s):

1. 6G3 - PETRA III (DESY) (POF4-6G3) (POF4-6G3)
2. INDIA-DESY - INDIA-DESY Collaboration (2020_Join2-INDIA-DESY) (2020_Join2-INDIA-DESY)
3. FS-Proposal: I-20230296 (I-20230296) (I-20230296)

Experiment(s):

1. PETRA Beamline P64 (PETRA III)

Appears in the scientific report 2026

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Database coverage:
; Clarivate Analytics Master Journal List ; Current Contents - Engineering, Computing and Technology ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; Essential Science Indicators ; IF >= 20 ; JCR ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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