Single sheet iron oxide: An efficient heterogeneous electro-Fenton catalyst at neutral pH

Area of Science:

• Environmental Chemistry
• Materials Science
• Electrochemistry

Background:

• Heterogeneous electro-Fenton processes often suffer from inefficiency at neutral pH.
• Developing stable and effective catalysts for water treatment is crucial.

Purpose of the Study:

• To develop a highly efficient heterogeneous electro-Fenton catalyst for water treatment at neutral pH.
• To investigate the degradation mechanism of azo dye Orange II using the novel catalyst.

Main Methods:

• Fabrication of single sheet iron oxide (SSI) from layered Fe(II)-Fe(III) double hydroxides (green rusts) on an indium tin oxide electrode.
• Utilizing an undivided electrolysis cell for dye degradation.
• Employing radical scavengers and advanced analytical techniques (UV-vis, LC-MS, GC-MS) to elucidate the degradation pathway.

Main Results:

• SSI electrode demonstrated efficient degradation of azo dye Orange II through electrochemical reduction of oxygen, forming hydroxyl and superoxide anion radicals.
• Both direct reduction and indirect oxidation mechanisms contributed to dye degradation.
• The SSI catalyst exhibited reactivity two orders of magnitude higher than homogeneous counterparts and maintained stability over 19 hours with no iron leaching.
• High dye removal efficiency was observed across a pH range of 7-10 and in various supporting electrolytes.

Conclusions:

• The developed SSI electrode offers a highly efficient, stable, and versatile solution for heterogeneous electro-Fenton water treatment at neutral pH.
• This technology shows promise for application in diverse water conditions, mimicking natural waters.