Fast and long-lasting Fe(Ⅲ) reduction by boron toward green and accelerated Fenton chemistry

Abstract

Generation of hydroxyl radicals in the Fenton system (Fe(II)/H 2 O 2 ) is seriously limited by the sluggish kinetics of Fe(III) reduction and fast Fe(III) precipitation. For the first time, we discover that boron crystals (C-Boron) remarkably accelerate the Fe(III)/Fe(II) circulation in Fenton-like systems (C-Boron/Fe(III)/H 2 O 2 ) to produce a myriad of hydroxyl radicals with excellent efficiencies in oxidative degradation of various pollutants. The surface B-B bonds and interfacial suboxide boron in the surface B 12 icosahedra are the active sites to donate electrons to promote fast Fe(III) reduction to Fe(II) and further enhance hydroxyl radical production via the Fenton chemistry. The C-Boron/Fe(III)/H 2 O 2 system outperforms the benchmark Fenton (Fe(II)/H 2 O 2 ) and Fe(III)-based sulfate radical systems. The reactivity and stability of crystalline boron is much higher than the popular molecular reducing agents, nanocarbons, and other metal/metal-free nanomaterials. Therefore, the discovery opens up a new avenue to leveraging metal-free boron for green oxidation and fast environmental decontamination.