3D hierarchical local heterojunction as ultra-highly efficient Fenton-like catalyst: Mechanism of coupling the proton-coupled electron transfer under nanoconfinement effect

Charge transfer in general type-II heterojunction is hard to realize and the transfer mode weakens the overall redox ability of the heterojunction. Band regulation and surface interface structural modifications assembled a novel visible-light-driven homogeneous catalyst (FeS 2 anchored on Mo 2 C aerogel), which activated the peroxymonosulfate (PMS) by proton-coupled electron transfer effect under the nanoconfinement effect. The degradation rate constant of the FeS 2 @Mo 2 C/PMS system is 11.4 times that of the PMS system and 2.6 times that of the Fe(Ⅱ) + Mo 2 C + PMS Fenton-like system. The initial pH has almost no effect on the degradation rate of the FeS 2 @Mo 2 C/PMS system. The EPR results show that the FeS 2 @Mo 2 C heterostructure can effectively catalyze the production of SO 4 · − , HO · and 1 O 2 by PMS, which is in agreement with the quenching results. DFT calculations demonstrate the existence of stable S Mo bonds in FeS 2 @Mo 2 C Schottky junctions. Thus S vacancies in FeS 2 significantly accelerated the transfer of FeS 2 photogenerated electrons to Mo 2 C, FeS 2 photogenerated holes can directly oxidize Azo dyes, extensively promoting the catalytic oxidation reaction rate. The prepared mesoporous catalysts (average pore diameter = 58.13 nm) through nanoconfinement effect can effectively accelerate the transmission speed to achieve the target pollutants > 99.9% removal rate in five min under sufficient catalyst. This paper provides a new perspective on applying Schottky heterojunctions coupled with photocatalytic technology for the effective degradation of Azo dyes.