3D ordered macro-/mesoporous carbon supported Ag nanoparticles for efficient electrocatalytic oxygen reduction reaction.

Three-dimensionally ordered macro-/mesoporous carbon (OMMC)-supported Ag nanoparticles (Ag/OMMC) with homogeneously dispersed Ag particles are prepared and investigated as effective electrocatalysts for oxygen reduction reaction (ORR) in alkaline aqueous system. The obtained Ag/OMMC catalyst displays smaller Ag particle size, higher Ag dispersion, and enhanced catalytic activity and durability compared with the carbon black Vulcan XC-72R supported Ag (Ag/XC-72R). The sizes of Ag particles supported on the OMMC and XC-72R are 4.3 and 6.5 nm, respectively. The prepared Ag/OMMC catalyst shows a positive half-wave potential of 0.79 V vs. RHE and a large diffusion-limited current of 5.6 mA cm-2 at 0.4 V, superior to Ag/XC-72R catalyst. The better ORR performance of the Ag/OMMC is probably ascribed to the unique 3D ordered interconnected macro-/mesoporous structure, which contributes to facilitating the mass/charge transport, improving the Ag particle dispersion, and preventing the Ag particle growth and aggregation.