Unravelling lewis acidic and reductive characters of normal and inverse nickel-cobalt thiospinels in directing catalytic H2O2 cleavage

Minsung Kim, Sang Hoon Kim, Jung Hyun Lee, Jongsik Kim

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

(Inverse) spinel-typed bimetallic sulfides are fascinating H2O2 scissors because of the inclusion of S2−, which can regenerate metals (Mδ+, δ ≤ 2) used to produce OH via H2O2 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 Niδ+/Coδ+ promising to H2O2 cleavage, Ni2CoS4, NiCo2S4, NiS/CoS were synthesized and contrasted with regards to their catalytic traits. Ni2CoS4 provided the greatest activity in dissecting H2O2 among the catalysts. Nonetheless, Ni2CoS4 catalyzed H2O2 scission primarily via homogeneous catalysis mediated by leached Niδ+/Coδ+. Conversely, NiCo2S4, NiS, and CoS catalyzed H2O2 cleavage mainly via unleached Niδ+/Coδ+-enabled heterogeneous catalysis. Of significance, NiCo2S4 provided Lewis acidic strength favorable to adsorb H2O2 and desorb OH compared to NiS and CoS, respectively. Of additional significance, NiCo2S4 provided S2− with lesser energy required to reduce M(δ+1)+ via e- transfer than NiS/CoS. Hence, NiCo2S4 prompted H2O2 scission cycle per unit time better than NiS/CoS, as evidenced by kinetic assessments. NiCo2S4 was also superior to Ni2CoS4 because of the elongated lifespan anticipated as OH producer, resulting from heterogeneous catalysis with moderate Niδ+/Coδ+ leaching. Furthermore, NiCo2S4 revealed the greatest recyclability and mineralization efficiency in decomposing recalcitrants via OH-mediated oxidation.

Original languageEnglish
Article number122347
JournalJournal of hazardous materials
Volume392
DOIs
Publication statusPublished - 2020 Jun 15

Keywords

  • Bimetallic sulfide
  • HO cleavage
  • Inverse spinel
  • OH
  • Refractory contaminants

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution
  • Health, Toxicology and Mutagenesis

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