Co3O4 modified polymeric carbon nitride for external light-free chlorine activating degradation of organic pollutants

Transformation of Graphitic Carbon Nitride by Reactive Chlorine Species: “Weak” Oxidants Are the Main Players

“…Free chlorine is one of the most widely used disinfectants for water and wastewater disinfection, and it has attracted broad attention for AOPs in recent years because it can be excited under UV irradiation and through catalysis to produce highly reactive RCS for effective contaminant removal. ,,,, As a promising photoreactive material, g-C 3 N 4 has been intensively investigated for photocatalytic oxidation and environmental remediation. ,, Some pioneering studies have validated the excellent performance of g-C 3 N 4 for RCS production and contaminant degradation. , Therefore, it is likely that, in the near future, g-C 3 N 4 will be used in engineering systems for water purification, and it can coexist with free chlorine and RCS. Our study revealed that g-C 3 N 4 nanosheets were mildly oxidized in free chlorine, but they lost structural integrity and decomposed rapidly under the attack of ClO· and/or Cl 2 •– , which calls for urgent attention to the material stability and robustness for long-term engineering applications.…”

“…37,71,72 Some pioneering studies have validated the excellent performance of g-C 3 N 4 for RCS production and contaminant degradation. 26,41 Therefore, it is likely that, in the near future, g-C 3 N 4 will be used in engineering systems for water purification, and it can coexist with free chlorine and RCS. Our study revealed that g-C 3 N 4 nanosheets were mildly oxidized in free chlorine, but they lost structural integrity and decomposed rapidly under the attack of ClO• and/or Cl 2…”

“…·OH are also ubiquitous in natural aquatic environments. They can be produced via the photolysis of nitrite, nitrate, and dissolved organic matter (DOM), photo-Fenton reactions, microbial activities, and overturn-induced aeration of anoxic bottom water. − Reactive chlorine species (RCS), like chlorine atoms (Cl·), chlorine oxide radicals (ClO·), and dichlorine radical anions (Cl 2 •– ), have attracted great attention for AOPs in recent years, − and they can be produced through ultraviolet light (UV)-activated photolysis of free chlorine and monochloramine. − Moreover, emerging technologies such as photocatalysis, electrocatalysis, and photoelectrocatalysis have been discovered to produce a high concentration of RCS for effective pollutant control. − Similar to ·OH, RCS are also ubiquitous in natural aquatic systems, especially in brines, estuaries, and seawater, and they are generated through the oxidation of chloride by ·OH, singlet oxygen ( 1 O 2 ), and photoexcited DOM. − When compared to ·OH, RCS oxidation could be less thermodynamically favorable due to their lower reduction potentials (the reduction potential of Cl·, Cl 2 •– , and ClO· is 2.5, 2.2, and 1.5–1.8 eV, respectively). ,, Moreover, RCS is more selective than ·OH: Cl· launches the electrophilic attack on aromatic rings whereas Cl 2 •– and ClO· prefer to react with aromatics with electron-donating groups through electron transfer. − However, RCS-induced oxidation is likely to form halogenated byproducts, which may raise concerns for human health and ecosystems. ,− …”

Core-shell structured Co3O4@PPy composite for electrochemical determination of terbutylhydroquinone

“…Cobalt tetroxide (Co 3 O 4 ) is considered to be the most active metal oxide catalyst with certain advantages, such as special chemical stability, large specific surface area and excellent surface redox performance. 12,13 Exposing redox reaction sites through rational design of the Co 3 O 4 structure is regarded as a high-efficiency strategy to boost its electrochemical sensing performance. Recently, some studies report a promising strategy on enhancing the electrochemical activity of an electrode by coating with a conducting polymer, which can adapt to the structure change and increase the electrode stability.…”

Pt/Au Nanoparticles@Co3O4 Cataluminescence Sensor for Rapid Analysis of Methyl Sec-Butyl Ether Impurity in Methyl Tert-Butyl Ether Gasoline Additive

“…In recent years, metal oxides such as WO 3 [6], ZnO [7], SnO 2 [8], and Co 3 O 4 [9] have been a common type of material used in various sensors. Owing to its good catalytic performance and low cost, Co 3 O 4 is a potential material for this application, and it has been widely studied in many fields [10][11][12]. In addition, as a p-type semiconductor material, the gas-sensing capability of Co 3 O 4 is based on the catalytic properties of its surface, and it has been widely used as a catalyst to improve the selective oxidation of various volatile organic compounds (VOCs) [9,13].…”