Radiolitically synthesized nano Ag/C catalysts for oxygen reduction and borohydride oxidation reactions in alkaline media, for potential applications in fuel cells

• Ag nanoparticle electrocatalysts synthesized via ɣ-irradiation method.
• The synthesis procedure offers greatly simplified in-situ catalytic ink preparation.
• Ag electrocatalysts tested for oxygen reduction and borohydride oxidation.
• Oxygen reduction proceeds as 4e− process with high kinetic currents.
• Borohydride hydrolysis is catalyzed parallel with its oxidation.

Carbon-supported silver nanoparticles (Ag:NPs/C) were synthesized by gamma irradiation-induced reduction method using the poly(vinyl alcohol) or poly(vinyl alcohol)/chitosan polymer as stabilizer. Prepared samples were characterized using transmission electron microscopy and X-ray diffractometry. Subsequently, Ag:NPs/C were studied using rotating disc and rotating ring disc method as electrocatalysts for ORR (oxygen reduction reaction) and BOR (borohydride oxidation reaction) for potential application in alkaline fuel cells. The synthesis method used herein offers simple and fast approach for catalytic ink preparation, since the ink is prepared in one-step radiation process, simultaneously with Ag+ ions reduction. Very high and stable catalytic efficiency toward ORR via 4e− path was evidenced during 4000 square pulse polarization cycles. BOR, accompanied with the simultaneous borohydride ion hydrolysis, was found to proceed at the oxidized Ag surface.