Surface Transformation in Lanthanum Nickelate for Enhanced Oxygen Evolution Catalysis

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Nickel-based perovskite oxides show promise as oxygen evolution reaction (OER) catalysts due to cost and tunability.
• Sluggish surface reconstruction kinetics hinder the performance and design of these catalysts.
• LaNiO3 typically exhibits low activity, necessitating strategies for performance enhancement.

Purpose of the Study:

• To develop a pre-etching strategy to improve the surface reconstruction of LaNiO3 for enhanced OER activity.
• To investigate the role of ferric ions in modifying the perovskite structure and catalytic performance.
• To elucidate the transformation of OER mechanisms following the pre-etching treatment.

Main Methods:

• Ferric ion pre-etching of LaNiO3 to induce lattice distortion and lower reconstruction energy barriers.
• In situ X-ray absorption spectroscopy (XAS) and in situ Raman spectroscopy to monitor surface transformations.
• Electrochemical testing to evaluate OER activity compared to RuO2 and NiFe layered double hydroxides (LDHs).

Main Results:

• Ferric ion hydrolysis generates protons that corrode La-O sites, facilitating reconstruction.
• Ferric ion substitution creates active sites, transforming low-activity LaNiO3 into a highly active catalyst.
• In situ studies reveal a transformation from corner-sharing to edge-sharing NiO6 at 1.43 V vs RHE, indicating a shift in OER mechanisms (LOM to AEM).

Conclusions:

• The ferric ion pre-etching strategy effectively enhances the surface reconstruction and OER performance of LaNiO3.
• The modified catalyst (LNFeIII-spe) outperforms benchmark catalysts like RuO2 and NiFe LDHs.
• The study demonstrates a novel approach to catalyst design by controlling surface reconstruction and mechanism transformation.