The design of high-performance and
cost-effective electrocatalysts
for water splitting is of prime importance for efficient and sustainable
hydrogen production. In this work, a surface defect engineering method
is developed for optimizing the electrocatalytic activity of perovskite
oxides for water electrolysis. A typical ferrite-based perovskite
oxide material La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) is used and regulated
by selective acid etching. The optimal parameters for the surface
treatment are identified. An efficient bifunctional perovskite oxide,
denoted LSCF-30, is prepared by selectively corroding the A-site Sr
element in the surface region, which is found to not only increase
the exposure and decrease the coordination of B-site metals but also
effectively modulate the electronic structure of these metals. The
crystal lattice of the perovskite bulk is kept constant during surface
engineering, which ensures the structural stability of the perovskite
catalyst. The findings demonstrate an effective strategy of surface
defect engineering in enhancing the performance of perovskite oxide
electrocatalysts for water splitting.
One core reaction involved in many electrochemical energy conversion systems is the oxygen evolution reaction (OER), which usually dominates the overall polarization loss due to its sluggish kinetics. Activating O2...
The development of a cobalt-free cathode with long-term stability and high electrochemical activity is important for constructing low-cost and robust solid oxide fuel cells (SOFCs). Here, we report performance enhancement of a cobalt-free cathode achieved by valence regulation of the ferrite-based perovskite. Utilizing co-doping of high valence niobium with low valence nickel, we developed a cathode material La 0.8 Sr 0.2 Fe 0.8 Ni 0.15 Nb 0.05 O 3Àδ that allowed representing adequate conductivity of 214 S cm À1 at 700 C, decent thermal compatibility with thermal expansion coefficient being 12 Â 10 À6 K À1 , superior electrochemical properties manifested by area-specific resistance of 0.06 Ω cm 2 and peak power density of 760 mW cm À2 at 800 C, and excellent discharge durability of over 480 h at a current density of 460 mA cm À2 under 750 C. This significantly enhanced performance originates from a proper regulation of the electronic structure rendered by synergistic effects induced by the co-doping of the high valence niobium with low valence nickel into the B sites of the ferrite perovskite. Such a regulation enables an optimized compromise among the oxygen vacancies, electronic mobility, oxygen adsorption and dissociation, and strontium segregation.
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