Zero-Valent Iron Inside Carbon Nanocube as an Efficient Peroxymonosulfate Activator toward Catalytic Oxidation of Organic Pollutants

The agglomeration tendency of nano zero-valent iron (Fe0) limits its practical applications toward catalytic oxidation of organic pollutants. Herein, an in situ encapsulation of polydopamine on the surface of Prussian blue (PB) nanocubes followed by a confined reduction treatment strategy was presented to confine the zero-valent iron nanoparticles (Fe0) inside hollow carbon nanocube (Fe0@C) as an efficient peroxymonosulfate (PMS) activator toward catalytic oxidation of toxic organic contaminants. The catalytic results showed that 100% degradation of bisphenol A (BPA) could be completed within 5 min with Fe0@C nanocube as a catalyst to activate PMS. This delicately designed Fe0@C nanocube displayed a superior kinetic rate constant compared with the pure Fe0 nanoparticles (4.2-fold). Experimental evidence revealed that the generation of multiple reactive oxygen species in the nanocubes played a vital role for the significantly enhanced catalytic efficiency for organic contaminants. Both SO4•–, •O2–, and •OH dominated radical processes, and nonradical pathways involving 1O2 were accounted for PMS activation and organic contaminant degradation. The superior catalytic performance was attributed to a carbon layer with large specific surface area and highly dispersed Fe0 nanoparticles to provide abundant active sites, distinct nanocube structure to concentrate the reactant molecules within a confined space, and an excellent electron/mass transport property.