In Situ Nanoconfinement Catalysis for Highly Efficient Redox Transformation

The rapid reduction of Cr(VI) across a wide pH range, from acidic to alkaline pH conditions to stable Cr(III) species for efficient remediation of Cr(VI) pollution, has long been a challenge. Herein, we propose a new concept of in situ nanoconfinement catalysis ( i NCC) for highly efficient remediation of Cr(VI) by growing nanosheets of in situ layered double hydroxide ( i LDH) on the surface of Al–Mg–Fe alloy achieving chemical reduction rates of >99% in 1 min from pH 3 to 11 for 100 mg L –1 Cr(VI) with a rate constant of 201 h –1 . In stark contrast, the reduction rate is less than 6% in 12 h with a rate constant of 0.77 h –1 for the pristine Al–Mg–Fe alloy. The ultrafast reduction of Cr(VI) is most likely attributed to the synergistic catalysis of Al 12 Mg 17 and Al 13 Fe 4 and nanoconfinement of MgAlFe- i LDH and superstable mineralization of Cr(III) by MgAlCr III - and MgFeCr III - i LDHs. This study demonstrates the potential of in situ nanoconfinement catalysis on redox transformation for environmental remediation.