Scheme 1
.
Illustration of the catalytic degradation mechanism of Co-NC900.
Fig. 1
.
Synthetic strategy and characterizations. a) A schematic illustration of the preparation strategy. b,c) HRTEM images of Co-NC900. d) XRD of Co-NC900F and Co-NC900. e) XPS survey spectra of Co, O, N, and C in Co-NCx (x represents the pyrolysis temperature). f) High-resolution Co 2p XPS spectra of Co-NC900 obtained after etching depth of about 10 nm. g) High-resolution N1s XPS spectra of Co-NCx. h) Raman spectra of Co-NCx. i) N
2
adsorption-desorption isotherms of Co-NC900. inset: The corresponding pore size distribution.
Fig. 2
.
a) Normalized Co K-edge XANES spectra of Co-NC900 with standard references. b) FT-EXAFS spectra of Co-NC900 in R-space with standard references. c-f) The wavelet transform of Co-NC900 (c) and the references of Co-foil (d), CoO (e), and Co
3
O
4
(f).
Fig. 3
.
Catalytic performance of Co-NC900/PMS process. a) IMD degradation performance in different reaction systems. b-d) Effect of IMD concentration, aqueous matrix, and ions (5 min) on IMD degradation by Co-NC900-activated PMS. e) The schematic illustration of the continuous flow system. f) Continuous operation test of IMD degradation in the continuous flow system. g) IMD degradation in 15 consecutive cycles in the Co-NC900/PMS system. h) Degradation of multiple pollutants in the Co-NC900/PMS system after 5 min reactions. Reaction conditions: [catalyst] = 0.05 g L
−1
, [PMS] = 0.5 mM, [pollutants] = 2.5 mg L
−1
(The concentration of glyphosate in
Fig. 2
h is 100 mg L
−1
), [Temp.] =25 ± 2 °C.
Fig. 4
.
a) ESR spectra of ROS detected in the Co-NC900/PMS system. Reaction condition: [Co-NC900] = 0.05 g L
−1
, [PMS] = 0.5 mM, [Temp.] =25 °C, [Time] = 2 min
−1
. b) The ratio of SO
4
•−
, HO
•
, and
1
O
2
exposure to PMS exposure. c) Concentrations of PMS and ROS in the Co-NC900/PMS system. d) Comparison of experimentally measured and model-predicted of IMD degradation rates in the Co-NC900 system. e) In the Co-NC900/PMS system, the fractional contribution of SO
4
•−
(
f
SO4
•−
), HO
•
(
f
HO
•
),
1
O
2
(
f
1
O2
), PMS (
f
PMS
), and adsorption (
f
ads
) to the degradation process of selected compounds. Reaction conditions for (b-e): [catalyst] = 0.005 g L
−1
, [PMS] = 0.5 mM, [pollutants] = 0.2 mg L
−1
, [Temp.] =25 ± 2 °C.
Fig. 5
.
(a) Modeling of Co-NC900. (b) Charge density difference analysis of Co-NC900, Yellow and blue colors represent electron accumulation and reduction regions, respectively, with an isosurface value of 0.0025
e
Å
−3
. (c-d) Comparison of LDOS of total carbon 2p orbitals of HC and CoC (c), HC-GrN and CoC-GrN (d), and comparison of PDOS of adsorption site C2p orbitals and N2p orbitals. The Fermi level is set as zero. (e) Comparison of adsorption energies of different models for OI and OII sites of PMS. (f) PMS bader charge increase for different adsorption models. (g-h) Charge density difference of the OI site and the OII site on PMS adsorbed by CoC-GrN model. (Isosurface value of 0.0025
e
Å
−3
). (i) Gibbs free energy change of two pathways for SO
4
•−
and HO
•
production by Co-C-GrN catalyzed PMS.
Dongchen Yang, Zexiu An, Jingqian Huo, Lai Chen, Haijiao Dong, Weidi Duan, Yaxin Zheng, Minghua Wang, Maoxia He, Shutao Gao, Jinlin Zhang, Ultrastable cobalt-based chainmail catalyst for degradation of emerging contaminants in water, Applied Catalysis B: Environment and Energy, 2025, https://doi.org/10.1016/j.apcatb.2024.124768
