Oil spill accidents on the sea and oily wastewater produced in daily life have posed serious threats to the environment. Therefore, there is an urgent need for a material that can effectively separate these mixtures using simple operations. Herein, an ecofriendly sandwich-structured coating with excellent superhydrophobic/superoleophilic properties was fabricated by in situ growth on copper mesh and cotton fabric substrates. Specifically, using the versatility of tannic acid (TA) film, including chelation and reduction with Cu