Uniform Mesoporous Amorphous Cobalt-Inherent Silicon Oxide as a Highly Active Heterogeneous Catalyst in the Activation of Peroxymonosulfate for Rapid Oxidation of 2,4-Dichlorophenol: The Important Role of Inherent Cobalt in the Catalytic Mechanism

Abstract

Amorphous cobalt-inherent silicon oxide (Co-SiOx) was synthesized for the first time and employed as a highly active catalyst in the activation of peroxymonosulfate (PMS) for the rapid oxidation of 2,4-dichlorophenol (2,4-DCP). The characterization results revealed that the 0.15Co-SiOx possessed a high specific surface area of 607.95 m 2 /g with a uniform mesoporous structure (24.33 nm). The X-ray diffraction patterns indicate that the substituted cobalt atoms enlarge the unit cell parameter of the original SiO 2 , and the selected area electron diffraction pattern confirmed the amorphous nature of Co-SiOx. More bulk oxygen vacancies (O v ) existing in the Co-SiOx were identified to be one of the primary contributors to the significantly enhanced catalytic activation of PMS. The cobalt substitution both creates and stabilizes the surficial O v and forms the adequately active Co(II)−O v pairs which engine the electron transfer process during the catalytic activities. The active Co(II)−O v pairs weaken the average electronegativity of Co/Si and Co/O sites, resulting in the prevalent changes in final state energy, which is the main driving cause of the binding energy shifts in the X-ray photoelectron spectroscopy (XPS) spectra of Si and O among all samples. The increase of the relative proportion of Co(III) in the spent Co-SiOx probably causes the binding energy shifts of the Co XPS spectrum compared to that of the Co-SiOx. The amorphous Co-SiOx outperforms stable and quick 2,4-DCP degradation, achieving a much higher kinetic rate of 0.7139 min −1 at pH = 7.02 than others via sulfate radical advanced oxidation processes (AOPs), photo-Fenton AOPs, H 2 O 2 reagent AOPs, and other AOP approaches. The efficient degradation performance makes the amorphous Co-SiOx as a promising catalyst in removing 2,4-DCP or organic-rich pollutants.

Interstitial Atomic Bi Charge‐Alternating Processor Boosts Twofold Molecular Oxygen Activation Enabling Rapid Catalytic Oxidation Reactions at Room Temperature

“…This phenomenon provides fundamental support for the following analysis. [14] Scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) measurements were conducted to define the morphology of the Bi NS, MnO 2 , and 0.1Bi/MnO 2 . In Figure S1 (Supporting Information), the morphology of MnO 2 regularly exhibits a 3D rambutan-like microsphere with a hollow center.…”

Ultrafast degradation of SMX and TC by CoSiOx activated peroxymonosulfate: efficiency and mechanism

“… 25 The relative content of O ads decreased, which may be attributed to the neutralization of OVs during the catalytic reaction, confirmed the involvement of OVs. 23 …”

“…However, OVs sites on the CoSiO x surface can increase the charge carrier density and then improve the electrical conductivity, promoting the regeneration of Co( ii ). 23 …”

“…11b, the O 1s spectrum could be deconvoluted into three characteristic peaks located at 532.9, 531.9, and 530.9 eV, corresponding to lattice oxygen (O lat ), hydroxyl groups (O -OH ), and adsorbed oxygen species (O ads , O 2 2− , O 2− and O − ), respectively. 23,24 To some extent, the O ads species could represent oxygen vacancies. 8 Surface hydroxyl can be used as active sites, producing a profound impact on the PMS activation and the production of reactive species.…”

Low–Medium Temperature-Selective Catalytic Reduction of NO with NH3 over a Mn/Co-MOF-74 Catalyst

“…Besides, the strength of the characteristic peak appeared to show more obvious difference with the change of the ratio of Mn and Co, proving that Mn and Co elements had been loaded successfully. It is worth noting that when the Mn/Co ratios are 3:1 and 2:1, respectively, a group of strong peaks in the range of 2θ = 18∼21° are observed, and the corresponding substances are determined as MnO 2 and Mn 2 O 3 by referring to literature , because in the microwave hydrothermal synthesis process, when the Mn content is too high, the oxidation and crystallization are likely to occur on the surface of the catalyst, and the manganese component eventually exists in the stable state of MnO 2 and Mn 2 O 3 . Besides, when the Mn/Co ratios are 3:1 and 2:1, respectively, the characteristic peaks of Co 3 O 4 also appear at 27.5 and 32.9°.…”