2026-10-06T06:17:27Z https://api.figshare.com/v2/oai

oai:figshare.com:article/34044513 2026-10-01T11:19:43Z category_1 category_146 category_915 category_7 category_12 category_16 category_272 category_873 category_45 portal_63 item_type_6 month_year_10_2026

The Effect of Oxygen Vacancies on Surface and Bulk Charge Storage in La_0.5Sr_0.5FeO_3−δ Alexander V. Dmitriev (365597) Elena V. Vladimirova (25156278) Anastasia A. Ivleva (25156281) Alexander D. Koryakov (25156284) Ilya S. Popov (25156287) Biophysics Space Science Physical Sciences not elsewhere classified Medicine Cell Biology Physiology Environmental Sciences not elsewhere classified Chemical Sciences not elsewhere classified Sociology ultrasonic spray pyrolysis ray photoelectron spectroscopy keeping crystal structure hollow spherical particles density functional theory 2p partial densities high defect levels electrochemical impedance spectroscopy bulk charge storage preserved electronic conductivity 5 </ sub 4 +</ sup 02 – 0 transition metal oxides δ ≈ 0 3 +</ sup charge storage electronic conductivity insulator transition defect engineering electronic percolation electrochemical performance electrochemical measurements specific capacity rational basis pronounced maximum progressive suppression perovskite electrodes oxygen vacancies oxygen deficiency observed degradation isolated contribution findings provide fermi level experimental findings exchange clusters controlled conditions 2 ah Oxygen vacancies are widely used to tune the electrochemical performance of transition metal oxides, yet their isolated contribution to charge storage remains difficult to quantify because vacancy concentration and morphology typically change simultaneously. Here, we investigate the effect of oxygen deficiency on charge storage in La_0.5Sr_0.5FeO_3−δ (δ = 0.02–0.38) while keeping crystal structure, morphology, and specific surface area essentially unchanged. Hollow spherical particles were synthesized by ultrasonic spray pyrolysis and reduced under controlled conditions. Electrochemical measurements in 3 M KOH reveal a pronounced maximum in specific capacity (0.2 Ah/g at 1 A/g), faradaic current, and heterogeneous electron transfer rate at δ ≈ 0.05; higher vacancy concentrations degrade performance. Step potential electrochemical spectroscopy and electrochemical impedance spectroscopy were used to separate surface and bulk charge storage contributions. X-ray photoelectron spectroscopy and electron paramagnetic resonance show that increasing δ sequentially reduces Fe⁴⁺ to Fe³⁺ and Fe²⁺, collapsing ferromagnetic double-exchange clusters and electronic percolation. Complementing these experimental findings, density functional theory (DFT) calculations on La_0.5Sr_0.5FeO_3‑δ reveal a progressive suppression of the Fe 3d and O 2p partial densities of states at the Fermi level with increasing oxygen vacancy concentration, leading to a metal-to-insulator transition at δ ≈ 0.25, consistent with the observed degradation of electronic conductivity at high defect levels. The optimal electrochemical response thus arises from a compromise between vacancy-enhanced electrolyte ions insertion and preserved electronic conductivity. These findings provide a rational basis for defect engineering in perovskite electrodes. 2026-10-01T00:00:00Z Text Journal contribution 10.1021/acs.jpcc.6c03001.s001 https://figshare.com/articles/journal_contribution/The_Effect_of_Oxygen_Vacancies_on_Surface_and_Bulk_Charge_Storage_in_La_sub_0_5_sub_Sr_sub_0_5_sub_FeO_sub_3_sub_/34044513 CC BY-NC 4.0