Unravelling lewis acidic and reductive characters of normal and inverse nickel-cobalt thiospinels in directing catalytic HO cleavage.

Author(s) Kim, M.; Kim, S.Hoon; Lee, J.H.; Kim, J.
Journal J Hazard Mater
Date Published 2020 Feb 18

(Inverse) spinel-typed bimetallic sulfides are fascinating HO scissors because of the inclusion of S, which can regenerate metals (M, δ ≤ 2) used to produce OH via HO dissection. These sulfides, however, were under-explored regarding compositional, structural, and electronic tunabilities based on the proper selection of metal constituents. Motivated by S-modified Ni/Co promising to HO cleavage, NiCoS, NiCoS, NiS/CoS were synthesized and contrasted with regards to their catalytic traits. NiCoS provided the greatest activity in dissecting HO among the catalysts. Nonetheless, NiCoS catalyzed HO scission primarily via homogeneous catalysis mediated by leached Ni/Co. Conversely, NiCoS, NiS, and CoS catalyzed HO cleavage mainly via unleached Ni/Co-enabled heterogeneous catalysis. Of significance, NiCoS provided Lewis acidic strength favorable to adsorb HO and desorb OH compared to NiS and CoS, respectively. Of additional significance, NiCoS provided S with lesser energy required to reduce M via e- transfer than NiS/CoS. Hence, NiCoS prompted HO scission cycle per unit time better than NiS/CoS, as evidenced by kinetic assessments. NiCoS was also superior to NiCoS because of the elongated lifespan anticipated as OH producer, resulting from heterogeneous catalysis with moderate Ni/Co leaching. Furthermore, NiCoS revealed the greatest recyclability and mineralization efficiency in decomposing recalcitrants via OH-mediated oxidation.

DOI 10.1016/j.jhazmat.2020.122347
ISSN 1873-3336
Citation J Hazard Mater. 2020;392:122347.

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