Carbon black supported ultra-high loading silver nanoparticle catalyst and its enhanced electrocatalytic activity towards oxygen reduction reaction in alkaline medium

► This work developed a facile method to synthesize ultra-high loading Ag/C catalyst. ► The Ag nanoparticles are densely loaded on carbon black surface without aggregation. ► The loaded Ag nanoparticles are ca. 10 nm diameter of fine spheres. ► The catalyst owns high electrocatalytic activity and stability for four-electron ORR.