Phosphate Shifted Oxygen Reduction Pathway on Fe@Fe₂O₃ Core–Shell Nanowires for Enhanced Reactive Oxygen Species Generation and Aerobic 4-Chlorophenol Degradation

Abstract

Phosphate ions widely exist in the environment. Previous studies revealed that the adsorption of phosphate ions on nanoscale zerovalent iron would generate a passivating oxide shell to block reactive sites and thus decrease the direct pollutant reduction reactivity of zerovalent iron. Given that molecular oxygen activation process is different from direct pollutant reduction with nanoscale zerovalent iron, it is still unclear how phosphate ions will affect molecular oxygen activation and reactive oxygen species generation with nanoscale zerovalent iron. In this study, we systematically studied the effect of phosphate ions on molecular oxygen activation with Fe@FeO nanowires, a special nanoscale zerovalent iron, taking advantages of rotating ring disk electrochemical analysis. It was interesting to find that the oxygen reduction pathway on Fe@FeO nanowires was gradually shifted from a four-electron reduction pathway to a sequential one-electron reduction one, along with increasing the phosphate ions concentration from 0 to 10 mmol·L. This oxygen reduction pathway change greatly enhanced the molecular oxygen activation and reactive oxygen species generation performances of Fe@FeO nanowires, and thus increased their aerobic 4-chlorophenol degradation rate by 10 times. These findings shed insight into the possible roles of widely existed phosphate ions in molecular oxygen activation and organic pollutants degradation with nanoscale zerovalent iron.

Versatile Luminol/Dissolved Oxygen/Fe@Fe2O3 Nanowire Ternary Electrochemiluminescence System Combined with Highly Efficient Strand Displacement Amplification for Ultrasensitive microRNA Detection

“…Fe@Fe 2 O 3 nanowires were prepared referring to the previous literature with minor changes. 14 Typically, 30 mg of FeCl 3 was dissolved in 10 mL of deionized water to form a clear yellow solution in a 50 mL beaker and then 4 mL of freshly prepared cold NaBH 4 solution (60 mg NaBH 4 ) was added dropwise into the above solution. With the addition of the NaBH 4 solution dropwise, bubbles appeared and burst, and fluffy black sediment appeared and sank.…”

Management of wilt disease of chickpea in vivo by silver nanoparticles biosynthesized by rhizospheric microflora of chickpea (Cicer arietinum)

“…Green synthesis of nanoparticles has received attention due to its use of environment-friendly precursors for nanoparticles synthesis with many other advantages such as economic viability, ease of production, eco-friendly nature, avoiding the use of harmful chemicals, conditions of high temperature and pressure, and the expensive instruments required for physical and chemical methods. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] Microorganisms have the ability to reduce heavy metal salts to metal nanoparticles with a narrow size distribution due to the presence of various reductase enzymes. 15 In a previous report, silver nanoparticles and PbS quantum dots were synthesized by Aspergillus sp.…”

Bagasse derived C@Fe3C/Fe3O4 composite: An Approach towards low cost electrocatalyst for oxygen reduction reaction

“…Clearly, inventing new high-activity nonprecious metal (NPM) ORR catalysts to replace Pt-based catalysts is critical. [10] In the last decades, there have been several reports on non-precious electrocatalysts such as inorganic nanoparticles (Cu1.4Mn1.6O4, TaCxFyOz/ g C, Ru), [11][12][13] transition metalnitrogen-carbon catalysts (Mn, Fe, Co and Ni based, Fe/Co containing N-doped porous carbon; iron-nitrogen/carbon), [14][15][16][17][18][19][20][21] transition metal oxides (Fe@Fe2O3), [22,23] non-metal (N, P, S, F etc) doped carbon materials, [24][25][26][27][28][29][30] CNT, [29,31] metal organic framework (MOF) based porous carbon [17,[32][33][34] etc. based electroactive materials have gained significant attention in order to overcome the cost and sluggish reaction kinetics of ORR.…”