Boron Bifunctional Catalysts for Rapid Degradation of Persistent Organic Pollutants in a Metal-Free Electro-Fenton Process: O₂ and H₂O₂ Activation Process

Abstract

Metals usually served as the active sites of the heterogeneous bifunctional electro-Fenton reaction, which faced the challenge of poor stability under acidic or even neutral conditions. Exploring a metal-free heterogeneous bifunctional electro-Fenton catalyst can effectively solve the above problems. In this work, a stable metal-free heterogeneous bifunctional boron-modified porous carbon catalyst (BTA-1000) was synthesized. For the BTA-1000 catalyst, the yield of H 2 O 2 (294 mg/L) significantly increased. The degradation rate of phenol by BTA-1000 (0.242 min −1 ) increased by an order of magnitude, compared with the porous carbon catalyst (0.0105 min −1 ). The BTA catalyst could rapidly degrade industrial dye wastewater, and its specific energy consumption was 5.52 kW h kg −1 COD −1 , lower than that in previous reports (6.38−7.4 kW h kg −1 COD −1 ). DFT and XPS revealed that C�O and −BC 2 O groups jointly promoted the generation of H 2 O 2 , and the −BCO 2 group played dominant roles in the generation of • OH because the oxygen atom near the electron-giving groups (−BCO 2 group) facilitated the formation of hydrogen bond and H 2 O 2 adsorption. This work gained deep insights into the reaction mechanism of the boron-modified porous carbon catalyst, which helped to guide the development of metal-free heterogeneous bifunctional electro-Fenton catalysts.

An Overview of Environmental Catalysis Mediated by Hydrogen Peroxide

“…In their review, for instance, Ribeiro et al [105] discussed the various activities of carbon materials as catalysts on their own and hybrid magnetic carbon nanocomposites in catalytic wet peroxide oxidation reactions for the degradation of organic pollutants. Apart from purely iron-based compounds that are currently being developed [106,107], several other doping/functionalizing moieties have been used on biochar and active carbons, such as Ag 3 PO 4 [108], MnO 2 , nitrogen [109], boron [110], B/N/graphene [111], N/S/Fe [112], FeAl-layered double hydroxide [113], copper oxides [114][115][116], CuNi [117], and Sr/Ce [118].…”

Urea and ammonium fluoride di-nitrogen and Cu & Fe bi-metal co-doped carbon felt as cathode for electro-Fenton degradation of norfloxacin: 1O2-dominated oxidation pathway

“…16,17 However, the prominent disadvantage of metal-loaded carbon catalysts is the leaching of the metal ions, especially under acidic conditions, 18,19 which may cause secondary pollution. Thus, to solve the problem of secondary pollution caused by leaching, some studies loaded non-metallic heteroatoms instead of metals on carbon materials, such as N, 20 S, 21 and B, 22 for the construction of metal-free electro-Fenton cathode catalysts. Among them, the N heteroatom not only has abundant sources including endogenous and exogenous, but also abundant in the nitrogen species generated during the doping process on carbons, and thus has been widely applied.…”

Electrocatalytic Generation of Singlet Oxygen via ROS-Mediated Redox Chain Reaction for Efficient Disinfection

“…The conversion of electrocatalytic two-electron oxygen reduction (2e-ORR) to H 2 O 2 provides a promising alternative to the synthesis of 1 O 2 precursor, which utilize H 2 O and O 2 for continuous and onsite production of H 2 O 2 , and Mo-based catalysts have been one of the popular metals to achieve this pathway, Mo doping can greatly improve the 2e-ORR activity and H 2 O 2 selectivity of the electrocatalyst. − Fe-based Fenton catalysis using Fe­(II) and H 2 O 2 to make strong oxidants has been traditionally applied to produce • OH or high-valent iron oxides but has been limited by the bottlenecks of narrow acid pH windows. , As reported, Fe-based catalysts can catalyze H 2 O 2 to produce 1 O 2 in an alkaline environment, it inspired us to design catalysts to produce 1 O 2 via the in situ EC generation of H 2 O 2 and subsequent selective activation of H 2 O 2 via a Fenton-like reaction. Such a possibility can be achieved by the effective synergy of bimetallic Mo- and Fe-sited catalysts .…”