Ascorbic acid-mediated solid-state synthesis of cavity-engineered CuO–Cu 2 O–Cu heterostructures: structural transformation mechanism and photocatalytic detoxification of Cr( vi )

Ascorbic-acid-assisted reduction of CuO generates a CuO–Cu 2 O–Cu heterostructure with enhanced interfacial charge transfer. The Z-scheme pathway promotes ˙O 2 − -mediated visible-light-driven Cr( vi ) reduction with high efficiency and stability.