Table 1: Oxygen reduction reaction characteristics of the PdCo catalysts evaluated in 0.5 M H2SO4 compared with those of Pt electrode and Pd electrode.

Electrode performanceb/mA cm−2 Specific activitye/μA cm−2 Onset potentiala/V 0.65 V versus Ag/AgCl 0.60 V versus Ag/AgCl 0.65 V versus Ag/AgCl 0.60 V versus Ag/AgCl Tafel slope/mV decade−1 Roughness factor/− Ref. Pt electrodef 0.72 3.5 × 10−2 1.1 × 10−1 8.4 2.7 × 101 71c, 116d 4.2 [60] Pd thin filmg 0.58 1.0 × 10−4 h 5.8 × 10−4 h 3.4 × 10−2 h 1.9 × 10−1 h 67 3.1 [11] PdCo thin filmf 0.66 2.4 × 10−2 2.6 × 10−1 1.5 1.6 × 101 44 16 [60] PdCo dendriteg 0.68 5.7 × 10−2 6.2 × 10−1 h 4.4 4.7 × 101 h 48 13 [15] Modified PdCo dendriteg 0.71 1.9 × 10−1 1.6h 1.1 × 101 9.2 × 101 h 55 17 [15] Nanoporous PdCo thin filmf 0.69 3.5 × 10−1 2.5 8.6 6.2 × 101 43 41 [60] Nanoporous PdCo dendriteg 0.72 3.9 × 10−1 i — 1.3i — — 290 [29]

aat the current density of 1 μA cm−2 (electrochemically active surface area). bbased on the geometrical surface area. c0.7–0.75 V. d0.55–0.65 V. ebased on the electrochemically active surface area. fmeasured by hydrodynamic voltammetry at room temperature (22°C). gmeasured by linear sweep voltammetry at (30°C). hestimated by extrapolating the Tafel slope. iwith a slight mass-transfer limitation.