Synthesis of Magnetic Cobalt Nanoparticles Anchored on Graphene Nanosheets and Catalytic Decomposition of Orange II

Abstract

Magnetic cobalt nanoparticles (NPs) at a size of approximately 29.9 nm anchored on graphene sheets were prepared and tested for heterogeneous oxidation of a dyeing pollutant, Orange II, with peroxymonosulfate (PMS) in aqueous solutions. The physicochemical properties of Co–graphene hybrids were investigated by various characterization techniques, such as powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectrometer (EDS), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The incorporation of Co NPs and graphene sheets produces much higher catalytic activity of Orange II degradation than pure Co. The Orange II decomposition rate increases with increasing temperature (25–45 °C), pH (4–10), and PMS dosage (0.04–0.60 g/L) but decreases with its increased concentration (30–120 mg/L). Kinetic studies show decomposition of Orange II on Co–graphene can be described by a pseudo-first-order kinetic model with activation energy of 49.5 kJ/mol.

Piezotronic-effect-enhanced Ag2S/ZnO photocatalyst for organic dye degradation

“…[18][19][20][21] Transition metals, such as Cu, Co, and Ni, have been investigated in an attempt to replace noble metals. [22][23][24] In semiconductor/semiconductor hybrid photocatalysts, metal oxides and suldes have been extensively applied to construct heterojunctions/interfaces that can effectively facilitate the spatial separation of photoexcited electron-hole pairs using suitable band alignment. In particular, for type II heterojunctions/interfaces, photoexcited electrons tend to transfer from the semiconductor with a narrower band gap to that with a wider band gap, while photoexcited holes oen transfer in the opposite direction due to the relative positions of the valence band (VB) and conduction band (CB).…”

Effects of nitrogen-, boron-, and phosphorus-doping or codoping on metal-free graphene catalysis

“…[8][9][10]. Sulfate radicals (SO 4 •− ) produced from PMS are believed to possess a higher oxidation potential (2.5-3.1 V) than hydroxyl radicals ( • OH, 2.7 V), then they not only present better oxidation towards phenol degradation, but are flexible to a broad range of pH solutions [11].…”

Magnetic carbon-supported cobalt prepared from one-step carbonization of hexacyanocobaltate as an efficient and recyclable catalyst for activating Oxone

“…As XPS analysis typically merely reveals surface composition due to its limited penetration depth (i.e., less than 10 nm), the XPS result only reflects the surface characteristics. Nevertheless, the metallic cobalt on the surface of MCC might be easily oxidized because its nanoscale size and high surface area [34,58,63].…”