Cavity-confined acceleration of iron cycle for the Fenton-like reaction by β-CD-benzoquinone host–guest complex under visible irradiation

• β-CD-benzoquinone (CDBQ) was readily prepared as cavity-confined co-catalyst.
• CDBQ efficiently accelerated Fe2 +/Fe3 + cycle under visible irradiation.
• The semi-quinone-like radical as an electron donor could coordinate with iron ions.
• The redox of Fe2 +/Fe3 + with quinones occurred within the β-CD's cavity.
• The cavity-confined acceleration has promising applications in photo-Fenton system.

The catalyst (CDBQ) that was prepared from β-cyclodextrin (β-CD) and 2,5-dihydroxy-1,4-benzoquinone (2,5-DBQ) achieved the cavity-confined acceleration of iron cycle under visible irradiation. The semi-quinone-like (SQ) radical was generated from photoexcitation of 2,5-DBQ within the β-CD's cavity. The SQ radical as an electron donor could coordinate with iron ions, and thus 2,5-DBQ shuttled one electron between Fe3 + and Fe2 + via Fe–dihydroxybenzoquinone complex process. In Fenton reactions, CDBQ greatly increased the HO yield, and thus significantly accelerated the degradation of dyes. The cavity-confined acceleration of iron cycle has promising applications in photo-Fenton system for the efficient decontamination for wastewater.

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