| Affiliation: | 1. Laboratory of Advanced Catalysis for Sustainability, School of Chemistry, University of Sydney, Sydney, NSW 2006 Australia;2. School of Materials Science and Engineering, UNSW Sydney, Sydney, NSW 2052 Australia These authors contributed equally to this work.;3. Centre for Advanced Materials & Industrial Chemistry (CAMIC), School of Science, RMIT University, Melbourne, VIC 3000 Australia;4. Departament de Física, Universitat Politècnica de Catalunya, Campus Nord B4-B5, 08034 Barcelona, Spain;5. Australian Centre for Microscopy and Microanalysis, The University of Sydney, Sydney, NSW 2006 Australia;6. School of Chemistry, UNSW Sydney, Sydney, NSW 2052 Australia |
| Abstract: | 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 °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. |
