Cation Substitution Induced d‐Band Center Modulation on Cobalt‐Based Spinel Oxides for Catalytic Ozonation

• Published in: Advanced functional materials Vol. 33; no. 44
• Main Authors: Qu, Wei, Tang, Zhuoyun, Tang, Su, Wen, Hailin, Fang, Jingyun, Lian, Qiyu, Shu, Dong, He, Chun
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 25-10-2023
• Subjects: Atomic oxygen; Catalysts; Cobalt oxides; Energy levels; Materials science; Metal-organic frameworks; Nickel; Poisoning (reaction inhibition); Raman spectra; Relative humidity; Room temperature; Spinel; Substitutes; Transition metal oxides; VOCs; Volatile organic compounds
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202301677

Abstract
Co
3
O
4
spinel is a promising transition metal oxide (TMO) catalyst for the catalytic ozonation of volatile organic compounds (VOCs). Herein, metal–organic frameworks (MOFs)‐derived Ni‐ and Mg‐ substituted Co
3
O
4
catalysts retain similar spinel structures, but display improved and reduced ozonation performance of methyl mercaptan (CH
3
SH), respectively. Remarkably, the NiCo
2
O
4
catalyst can still ≈90% removal of CH
3
SH after running for 20 h at room temperature under an initial concentration of 50 ppm CH
3
SH and 40 ppm O
3
, relative humidity of 60%, and space velocity of 300 000 mL h
−1
g
−1
, exceeding the reported values. Experimental characterizations have unveiled that the substitution of Ni and Mg into the Co
3
O
4
spinel altered surface acidity, oxygen species mobility, and Co
2+
/Co
3+
ratio. The in situ Raman spectra reveal the dynamic formation Co(III)‐O
ad
* via the transformation of O
3
into surface atomic oxygen (O
ad
*) and peroxide species (O
2
*). Theoretical calculations verify that Ni‐substitution increases nonuniform charges and Fermi density, leading to a moderate increase in d‐band center energy levels, thereby promoting O
3
specific adsorption/activation to convert O
ad
*/O
2
* and •OH/
1
O
2
/•O
2
−
, which contributes to eliminate CH
3
SH and prevent poisoning. The concept of tuning the d‐band center can provide valuable insights for the design of other catalysts for catalytic ozonation.