Selective Electrocatalytic Reduction of Oxygen to Hydroxyl Radicals via 3‐Electron Pathway with FeCo Alloy Encapsulated Carbon Aerogel for Fast and Complete Removing Pollutants

Abstract

We reported the selective electrochemical reduction of oxygen (O 2 )t oh ydroxylr adicals (COH) via 3-electron pathway with FeCo alloye ncapsulated by carbon aerogel (FeCoC). The graphite shell with exposed -COOH is conducive to the 2-electron reduction pathway for H 2 O 2 generation stepped by 1-electron reduction towardst oCOH. The electrocatalytic activity can be regulated by tuning the local electronic environment of carbon shell with the electrons coming from the inner FeCo alloy. The new strategy of COH generation from electrocatalytic reduction O 2 overcomes the rate-limiting step over electron transfer initiated by reduction-/oxidation-state cycle in Fenton process.F ast and complete removal of ciprofloxacin was achieved within 5min in this proposed system, the apparent rate constant (k obs )w as up to 1.44 AE 0.04 min À1 ,w hich is comparable with the state-of-the-art advanced oxidation processes.T he degradation rate almost remains the same after 50 successive runs,s uggesting the satisfactory stability for practical applications.

Activity Trends and Mechanisms in Peroxymonosulfate‐Assisted Catalytic Production of Singlet Oxygen over Atomic Metal‐N‐C Catalysts

“…Meanwhile,t he catalytic activity of Fe-SACi s much better than that of Fe nanoparticles (Figure S17), and the other M-SACs also achieved ahigh degradation rate and k values,which confirm that engineering the carbon-supported Thep otential catalytic reduction activity of M-SACs to different oxidants (PMS,O 2 ,and H 2 O 2 )was further evaluated by electrochemical reduction polarization curves. [16] As shown in Figure 3i,F igure S18,S19, and Table S8,S9, the specific activities of M-SACs for catalyzing different oxidants are calculated and verified by the TOFv alues.N otably,t he Fe-SACr eveals the highest TOF value (0.083 s À1 )among different M-SACs in PMS solutions (10 mg L À1 ). Meanwhile,t he change of TOFv alues for different oxidants reduction gives similar trends as that of the k values,i ndicating that the intrinsic PMS catalytic activity of M-SACs is associated with its electrochemical reduction activity.…”

“…[1,[7][8][9][10] As one of the most efficient AOPs,t he PMSassisted catalytic production of ROSv ia transition metal compounds has gained considerable interest. [9,[11][12][13] Despite abundant transition metal-based catalysts have already been developed and used in PMS-assisted AOPs, [14][15][16][17] obvious drawbacks such as the fast release of metal ions,slow catalytic kinetics,l ow atomic utilization rates,a nd unclear catalytic mechanisms have also been noticed.…”

Mesoporous transition metal oxides for oxygen electrocatalysis in energy conversion technologies

“…The hydroxyl radical (chemical formula: 𝑂𝐻 • ) has the highest oxidation potential (2.8 V versus standard hydrogen electrode) amongst reactive oxygen species. Therefore, it has been used as oxidant in advanced oxidation processes, e.g., degradation of organic pollutants and water treatment [18][19][20]. Conventionally, the hydroxyl radical and other reactive oxygen species have been widely studied in photocatalysis using semiconductor materials, e.g., TiO2, ZnO, BiVO4 etcetera [21,22].…”

“…Conventionally, the hydroxyl radical and other reactive oxygen species have been widely studied in photocatalysis using semiconductor materials, e.g., TiO2, ZnO, BiVO4 etcetera [21,22]. However, generation of 𝑂𝐻 • via electrocatalysis oxygen has been rarely reported [20]. It is a promising approach to synthesize…”

Super‐Coordinated Nickel N4Ni1O2Site Single‐Atom Catalyst for Selective H2O2Electrosynthesis at High Current Densities

“…And the N 1s can be decomposed to five peaks, [13] And the peak centered at 532.4 eV could be assigned to Nibonded O. [14] To analyze the structure details of the catalysts, the XANES (X-ray absorption near-edge structure) and EX-AFS (extended X-ray absorption fine structure) measurements were utilized. In Figure 2d Inspired by the unique coordination structure of N 4 Ni 1 O 2 /OCNTs, the 2 e À ORR electrocatalytic performance was firstly examined in a flow-cell setup in 1 M KOH using linear sweep voltammetry with manually 80 % iRcompensated [15] (Figure 3a).…”