期刊
CHEMISTRY-A EUROPEAN JOURNAL
卷 27, 期 58, 页码 14418-14426出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/chem.202102672
关键词
electrocatalysts; oxygen evolution reaction; perovskite; surface defects
资金
- University of Sydney Research Fellowship [G197582]
- ARC [DP200100313]
- Spanish Ministry of Science, Innovation and Universities under the Ramon y Cajal fellowship [RYC2018-024947-I]
The study found that the formation of oxygen vacancies on the surface of LaNiO3 perovskite electrocatalysts enhanced their OER activity and stability, leading to different activity characteristics, which occurred under hydrogen reduction at 700 degrees Celsius.
Perovskite oxides are regarded as promising electrocatalysts for water splitting due to their cost-effectiveness, high efficiency and durability in the oxygen evolution reaction (OER). Despite these advantages, a fundamental understanding of how critical structural parameters of perovskite electrocatalysts influence their activity and stability is lacking. Here, we investigate the impact of structural defects on OER performance for representative LaNiO3 perovskite electrocatalysts. Hydrogen reduction of 700 degrees C calcined LaNiO3 induces a high density of surface oxygen vacancies, and confers significantly enhanced OER activity and stability compared to unreduced LaNiO3; the former exhibit a low onset overpotential of 380 mV at 10 mA cm(-2) and a small Tafel slope of 70.8 mV dec(-1). Oxygen vacancy formation is accompanied by mixed Ni2+/Ni3+ valence states, which quantum-chemical DFT calculations reveal modify the perovskite electronic structure. Further, it reveals that the formation of oxygen vacancies is thermodynamically more favourable on the surface than in the bulk; it increases the electronic conductivity of reduced LaNiO3 in accordance with the enhanced OER activity that is observed.
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