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Download fileSoft Chemical Fabrication of Iron-Based Thin Film Electrocatalyst for Water Oxidation under Neutral pH and Structure–Activity Tuning by Cerium Incorporation
journal contribution
posted on 2017-08-17, 00:00 authored by Jony Saha, T. P. RadhakrishnanDesign of electrocatalysts for the
fundamentally important oxygen
evolution reaction can be greatly aided by systematic structure–activity
tuning via composition variation. We have explored the iron–cerium
system as they are the most abundant transition and rare earth metals,
and also due to the mutualistic impact of their size and electronic
attributes that can induce critical changes in the structure and electrochemical
activity. Submicrometer thick films of a series of Fe(III)–Ce(III)
phosphate(oxyhydroxide) (FeCePH) are fabricated using a soft chemical
strategy involving surfactant-aided assembly, spin-coating, and mild thermal annealing. FT-IR, Raman,
and X-ray photoelectron spectroscopies, chemical analysis, X-ray diffraction,
and electron microscopy reveal the systematic structural, electronic,
and morphological variation, on tuning the iron–cerium composition.
Nitrogen adsorption–desorption studies show the surface area
increasing and pore size distribution shrinking with the cerium content,
indicating its structure-directing role. The electrocatalysis of water
oxidation by FeCePH films on FTO-coated glass is studied in neutral
pH conditions. The overpotential and Tafel slope decrease with increasing
cerium content, reaching minima at the optimal Fe:Ce ratio of 1:0.5;
the turnover frequency shows a corresponding increase and maximum.
The trends are explained on the basis of the structural changes in
the films, and the coupling of Ce3+/Ce4+ with
Fe3+/Fe4+ that leads to active state regeneration.
This study presents a rational strategy to tune the efficiency of
easily fabricated transition metal-based electrocatalyst thin films
through rare earth metal incorporation; it should prove useful in
the design of cost-effective catalysts for water oxidation.