In Situ Electrochemical Fabrication of Three Dimensional Hierarchical Nanoporous Copper Films and Their Electrocatalytic Performance

We reported a facile strategy to fabricate three dimensional (3D) hierarchical nanoporous Cu films via simple in-situ electrochemical alloying/dealloying approach in a choline chloride-ethylene glycol (ethaline) deep eutectic solvent (DES) containing zinc chloride. The fabrication process involved electrochemical formation of Cu-Zn surface alloys (alloying), and followed by in-situ selective etching of the active zinc element from the alloys (dealloying). Compared with those exerted from choline chloride-urea (reline) based DES, the resultant nanoporous Cu (NPC) films obtained in ethaline exhibited a hierarchical porous architecture with a tailorable channel/pore size distribution. The evolution of nanoporosity was found to be highly temperature and time dependent, suggesting a thermal activation process controlled by surface diffusion. For kinetics investigation, the surface diffusivities of self-assembled copper atoms at the hierarchical layers, and their corresponding activation energies have been evaluated. The as-prepared NPC showed a significant catalytic activity for reduction of nitrate with a linear detection range of 10–100 μM. A fairly high nitrate sensitivity of 3415 μA mM−1 cm−2 coupled with a low detection limit of 1.92 μM is achieved.