Industrial & Engineering Chemistry Research, Vol.59, No.51, 22040-22048, 2020
Highly Efficient Peroxymonosulfate Activation by Surface Oxidized Nickel Phosphide with Dual Active Sites
The nanocrystalline nickel phosphide (Ni2P) was synthesized through a chemical transformation process using nickel oxalate as a new precursor, and its highly efficient activation of peroxymonosulfate (PMS) for the degradation of organic dyes in water was demonstrated for the first time. The Ni2P with the charged nature of nickel (Ni delta+) and phosphorus (P delta-) provides the tunable surface Ni valence and electron-rich P center, where Ni delta+ synergically cooperating with surface oxidation layers facilitates the redox cycle of Ni3+/Ni2+ while P delta- achieves the electron transfer regulation. Such unique dual active sites greatly boost the PMS activation to realize the pollutant degradation with high efficiency and fast kinetics. The Ni2P could completely remove 100 mg L-1 of methylene blue (MB) in 12 min, yielding a high reaction rate constant of 0.342 min(-1), which is 43 and 29 times as high as that of nickel oxalate and oxalate-derived nickel oxide, respectively. Both the sulfate and hydroxyl radicals are primary reactive species dominating catalytic activity in the Ni2P/PMS system. This work would provide a new method for the rational design of transition metal phosphide for PMS activation.