Leaflike Cu–O–Sn nanosheets were prepared via a facile one-pot and template-free hydrothermal method.

Surface segregation of Sn occurred.

Surface defects were generated by introducing an appropriate amount of Sn species.

Cu–O–Sn exhibited extraordinarily high catalytic activity for dimethyldichlorosilane synthesis.

The quantities of surface defects were correlated with the catalytic performance of the catalysts.