The enhanced peroxymonosulfate activation ability and mechanism on low-coordinated Fe-N3 single sites for organic pollutant degradation in wastewater
Qi Zhou, Na Lv, J. Wang, Huizhong Shi, Jiao-Jiao Song
Abstract
For boosting the intrinsic peroxymonosulfate (PMS) catalytic activity of single atom catalysts (SACs), we fabricate zeolitic imidazolate framework (ZIF)-derived Fe SAC with different nitrogen coordination numbers (denoted as Fe-N x /C) to boost organic pollutant oxidation. X-ray absorption fine structure (XAFS) spectroscopy was undertaken to determine the coordination configuration of Fe–N path. As expected, the resultant Fe-N 3 /C exhibited more excellent PMS catalysis activity with a p-nitrophenol (4-NP) degradation kinetic rate constant (k obs ) of 0.061 min −1 that is 2.4-fold enhancement relative to the Fe-N 4 /C. Electron paramagnetic resonance (EPR) measurements and quenching tests confirmed the 1 O play the main role associated with high-valent Fe–oxo and a small amount of OH and SO 4 − species. Density functional calculations revealed that low coordinated Fe–N 3 sites prefer to form a bridge coordination bond structure of O-Fe-O with the adsorption sites of O2 and O1 in PMS molecule, exhibiting stronger interaction with the oxidant and better electron donating capability to enhance PMS activation comparing to common Fe-N 4 structure based on charge deformation density, electron localization function (ELF) and projected density of state (PDOS) analysis. These findings indicate that microstructure modulation is a useful avenue to prepare a high-performance Fenton-like SACs.