3.2. Electrocatalytic characteristics of Cu/AC cathode
Fig. 3. (a) Nyquist plots of EIS by bare AC and Cu/AC air cathodes. Lines marked as ‘Cal’ were fitting data from AF 12198 equivalent circuit. (b) Tafel plots of different air–cathode.Figure optionsDownload full-size imageDownload as PowerPoint slide
Fitting results of different cathodes based on the equivalent circuit.Raw-ACAC/CuR0 (Ω)15.659.112Cdl (10−7 Ω−1 sn cm−2)0.30660.1707ndf0.67070.8602Rd (Ω)0.53120.3013W (Ω S−1/2)1.31920.3385Cad (Ω−1 sn cm−2)0.001250.00078nad0.66140.6707Rct (Ω)9.3981.381Full-size tableTable optionsView in workspaceDownload as CSV
3.3. Characterization of Cu2O
The morphologies for raw-AC and Cu/AC cathodes are given in Fig. S2. The activated carbon showed the random pore size distribution and interconnected pore systems. Also, the tight and brawny PTFE fibers were present in the AC granules. However, the morphology of the Cu2O coated activated carbon was ribbon-like and respiratory surface was totally different from the bare activated carbon. Interconnected ribbons with submicrometer scale on the AC surface could be clearly observed. Compared with the reported Cu2O cubes, Cu2O balls (Yan et al., 2012) and Cu2O stars (Grez et al., 2012), these ribbon-like Cu2O was firstly observed and the deposited-Cu2O ribbons on AC could increase the roughness of the AC, resulting more activated sites for ORR.