NiCo2O4/BiOCl/Bi24O31Br10 ternary Z-scheme heterojunction enhance peroxymonosulfate activation under visible light: Catalyst synthesis and reaction mechanism

The Z-scheme heterostructure for photocatalyst can effectively prolong the lifetime of photogenerated carriers and retain a higher conduction/valence band position, promoting the synergistic coupling of photocatalysis and peroxymonosulfate (PMS) activation. In order to fully utilize the luminous energy and realize the efficient activation of PMS, this work achieved successful construction of NiCo2O4/BiOCl/Bi24O31Br10 ternary Z-scheme heterojunction by simultaneously synthesizing BiOCl and NiCo2O4 with NiCl2 and CoCl2 as the precursors. The intercalated BiOCl could serve as a carrier migration ladder to further achieve the spatial separation of electron-hole pairs, so that the oxidation and reduction processes separately occurred in different regions. Compared with the reported catalysts, the as-prepared composites exhibited the enhanced removal efficiency for tetracycline hydrochloride (TCH) in the visible light/PMS system, with a degradation efficiency of 85.30% in 2 min, and possessed good stability. Z-scheme heterojunction was shown to be beneficial for maximizing the superiority of photo-assisted Fenton-like reaction system. The experimental and characterization results confirmed that both non-radicals (1O2) and radicals (SO5•− and SO4•−) were involved in the reaction process and the SO5•− generated by the oxidation of PMS played a crucial role in the TCH degradation. The possible reaction mechanism was finally proposed. This study provided new insight into the Z-scheme heterostructure to promote the photo-assisted Fenton-like reaction.