Highly Efficient Peroxymonosulfate Activation by Surface Oxidized Nickel Phosphide with Dual Active Sites

Abstract

The nanocrystalline nickel phosphide (Ni 2 P) 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 Ni 2 P with the charged nature of nickel (Ni δ+ ) and phosphorus (P δ-) provides the tunable surface Ni valence and electron-rich P center, where Ni δ+ synergically cooperating with surface oxidation layers facilitates the redox cycle of Ni 3+ /Ni 2+ while P δachieves 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 Ni 2 P 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 Ni 2 P/PMS system. This work would provide a new method for the rational design of transition metal phosphide for PMS activation.

Modifying the 316L stainless steel surface by an electrodeposition technique: towards high-performance electrodes for alkaline water electrolysis

“…The presence of the oxidized nickel species (Ni 2+ /Ni 3+ ) in 15NiP@SS is due to the sensitive superficial oxidation of nickel phosphide when exposed to air. 83,91–93 This is reasonable since similar surface oxidation was often observed for metal phosphide materials when exposed to air. 81,91,94,95 In Fig.…”

“…83,91–93 This is reasonable since similar surface oxidation was often observed for metal phosphide materials when exposed to air. 81,91,94,95 In Fig. 3c a high-resolution spectrum of the P 2p displays three peaks at 128.56 eV and 130.55 eV, reflecting the BE of P 2p 3/2 and P 2p 1/2 , respectively in phosphides, while the peak at around 132.97 eV exemplifies the oxidized P species owing to air exposure.…”

Incorporation of Metal Phosphide Domains into Colloidal Hybrid Nanoparticles

“…Closer examination of the TEM and HAADF-STEM images reveals that the Ni 2 P and PbS domains are separated by a thin oxide layer that covers Ni 2 P. The presence of the oxide layer is confirmed by the STEM-EDS element map for O, which shows a concentrated O signal surrounding the particles with some colocalization with Ni. This observation is consistent with literature reports describing the surface chemistry of metal phosphides. ,,, The HRTEM image shows that both domains are crystalline and that only the Ni 2 P domain is surrounded by an amorphous oxide shell. The amorphous oxide layer extends between the Ni 2 P and PbS domains, suggesting that it formed in situ during synthesis and not during drying.…”

“…This observation is consistent with literature reports describing the surface chemistry of metal phosphides. 39,41,64,65 The HRTEM image shows that both domains are crystalline and that only the Ni 2 P domain is surrounded by an amorphous oxide shell. The amorphous oxide layer extends between the Ni 2 P and PbS domains, suggesting that it formed in situ during synthesis and not during drying.…”

Non-Negligible Oxygen Atoms in Transition Metal Phosphides: Research on the Role of Oxygen in Hydrodechlorination

“…From the perspective of active components, it is generally believed that the activity of phosphide catalysts is primarily derived from the role of phosphating. 60,61 Nevertheless, this research reveals that catalytic activity may be inseparably related to the newly formed Mo−P−O bonds. Subsequently, the changes of the valence states in different elements of MoP after HDC were compared.…”