Electrochemistry
Pyrite mesocrystals reconstruct into OER catalysts
Open access · cc by · source: Europe PMC
Oleylamine-grown (NiFe)S2 porous cubes form by cluster aggregation; Fe-doped samples reach η10 < 260 mV after converting to S-doped (oxy)hydroxides.
Study at a glance
- Design
- Other — NiFeS2 pyrite mesocrystal growth and OER pre-catalyst evaluation
- N
- Materials synthesis and electrocatalysis — no sample N
- Population
- Fe-doped NiS2 pyrite mesocrystals on GCEs
- Outcome
- OER overpotential and post-CV transformation to active (oxy)hydroxide
Structured fields used in claim comparison tables when every cited study has a complete layer.
Key findings
40–50 nm nearly single-crystalline porous cubes grow from <2 nm clusters at 180 °C. Fe-doped PCs have η10 < 260 mV vs 351 mV for NiS2. After CVs the real catalyst is amorphous S-doped metal (oxy)hydroxide; Fe helps retain S.
Methodology
Authors heated Ni(NO3)2/TAA in oleylamine, doped Fe, used TEM/SAED to map mesocrystal growth, then measured OER and post-CV spectroscopy.
Limitations
Atomic OER cycle on the reconstructed surface is not solved; GCE η10 is not a device metric.
How this study connects
Role on claims
Each row is a claim on a concept or method page where this paper supports, challenges, or qualifies the statement. Roles are hand-checked — not a model guess.
TEM/SAED of a pre-catalyst can disagree with the working catalyst. Fe-doped NiFeS₂ pyrite mesocrystals grow as 40–50 nm nearly single-crystalline porous cubes from <2 nm clusters at 180 °C, with η₁₀ < 260 mV versus 351 mV for NiS₂. After CVs the real OER catalyst is an amorphous S-doped metal (oxy)hydroxide; Fe helps retain S. The cubes TEM imaged are not the surface that evolves oxygen.
Evidence for the claim as stated.
A TEM image of the as-made solid can be characterisation while the mechanism lives elsewhere. Pyrite mesocrystal cubes (40–50 nm, SAED nearly single-crystalline) reconstruct into amorphous (oxy)hydroxide under OER CVs; SAXS, not TEM, clocks PISA nucleation at 9–10 min. Treating the first image as the operating structure is the disagreement between those papers and a simple 'TEM showed the catalyst/morphology' sentence.
Evidence for the claim as stated.
Open questions
Tensions this paper is part of
From concept pages' “where studies disagree.” Disagreement means the same question; scope means different assays, populations, or outcomes.
A TEM image of the as-made solid can be characterisation while the mechanism lives elsewhere. Pyrite mesocrystal cubes (40–50 nm, SAED nearly single-crystalline) reconstruct into amorphous (oxy)hydroxide under OER CVs; SAXS, not TEM, clocks PISA nucleation at 9–10 min. Treating the first image as the operating structure is the disagreement between those papers and a simple 'TEM showed the catalyst/morphology' sentence.
Related papers in this topic
Same topic cluster — not a recommendation engine.