Highly efficient and continuous activation of O by a novel FeP-FeCu composite for water purification and insights into the activation mechanisms through DFT calculation.

Degradation of organic pollutants through O activation catalyzed by transitional metals is challenging without addition of external chemicals and input of energy. We prepare a novel Fe based catalyst by compositing carbon, iron phosphide (FeP), iron carbide (FeC), Fe and Cu NPs, which can continuously activate O to produce high amount of O,·O and·OH radicals in a wide pH range. DFT calculation discloses that O molecules are dissociated into *O or exist as O-O in various configurations. The Fe-O, Cu-O and FeP-O surfaces can react with HO molecules to generate *OOH, *OH and/or OH. The sorbed-O intermediates on FeC surface might be released as O or·O. The oxidative O-sorbed surfaces and in-situ produced oxygen reactive species contribute to the efficient and pH-indenpendent degradation of organic pollutants. Cu NPs accelerate Fe/Fe cycles and offer impetus to initiate O activation due to the potential difference between Fe and Cu. The recycling test and XPS results confirm that the mutual electron transferring among carbon, FeC, FeP, Fe and Cu maintains reactivity and stability of the catalysts.