Electro-reduction of O2 to generate H2O2 is an attractive alternative to the current
anthraquinone
process and quite necessary for chemical industries and environmental
remediation. In general, sufficient porous structure contributes to
expose more catalytic active sites and shorten diffusion paths for
the heterogeneous catalysis of O2. In this work, initially
the Fe3O4 nanoparticles embedded graphite felt
(Fe3O4@GF) is prepared through a mild hydrothermal
following with thermal reduction method. This special combination
not only provides iron source for the electro-Fenton reaction but
also supplies rich active sites from the Fe3O4 embedded structure with abundant cracks, which are beneficial to
increase the reaction rate. Compared with raw graphite felt (RGF),
fresh Fe3O4@GF exhibits superior pollutant degradation
kinetics with more than 400% increase and approximately 37.8% improvement
to the removal of total organic carbon. A 98% decolorization of rhodamine
B (RhB) can be achieved in just 5 min and quickly completes 100% removal
of RhB in the next few seconds. As the electro-Fenton reaction progresses,
Fe3O4 dissolves in the electrolyte, leaving
a porous structure on the surface of the GF to form a porous GF (PGF),
and the rapid radical reaction activates the GF surface. Both the
chemical etching of Fe3O4 and the electro-Fenton
process can further increase the specific surface area, defects, and
actives sites of the electrode. As expected, the active PGF exhibits
favorable performance of H2O2 production in
electrolytes of different pHs: 1 (320.0 ± 36.5 mg L–1), 3 (301.9 ± 13.2 mg L–1), and 7 (320.4 ±
21.2 mg L–1). The degradation performance of PGF
does not significantly decay even after 20 cycles of repeated use,
indicating the good structural stability and long-term durability.
The superiority of the in situ Fe source and fast reaction kinetics
for electro-Fenton of Fe3O4@GF is confirmed,
and this holey engineered strategy also provides the possibility to
achieve swift water purification and open up a new way for developing
efficient carbon-based electrodes.
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