fig6

Figure 6. (A) Pictures of the prepared electrodes derived from IF, NF, CF and SSM substrates; (B) A comparison of the current density delivered at 200 mV overpotential; (C) HER polarization curves of the prepared RuO₂/NiFe(OH)_x, C-IF, C-NF, C-CF and C-SSM electrocatalysts, and (D) the associated overpotential comparison at 100 mA cm^-2; (E and F) Photos of synthesizing large-size RuO₂/NiFe(OH)_x electrode in 100 mM NiCl₂ and 2 mM RuCl₃ solutions; (G and H) Photos of the prepared large-size NiFe(OH)_x and RuO₂/NiFe(OH)_x electrodes; (I) Polarization curves of RuO₂/NiFe(OH)_x and large-size RuO₂/NiFe(OH)_x for HER. IF: Iron foam; NF: Ni foam; CF: Cu foam; SSM: stainless steel mesh; HER: hydrogen evolution reaction; NFF: NiFe foams; RHE: reversible hydrogen electrode.