In-situ synthesis, operation and regeneration of nanoporous silver with high performance toward oxygen reduction reaction

Highlights: • The NPS is synthesized as an efficient ORR catalyst by an anodization-electroreduction method. • The enhanced ORR performance of NPS is investigated by experiments and DFT calculations. • The in-situ regeneration is showed as a novel strategy to extend the service life of ORR catalysts. -- Abstract: Oxygen reduction reaction (ORR) plays a major role in the efficient operation of many important electrochemical energy devices. Herein, a novel catalyst of nanoporous silver (NPS) is in-situ synthesized by a high voltage anodization method in 0.1 M KOH which also serves as the electrolyte for the catalysis of ORR. Favored by the continuous pore channels, the mass transfer is enhanced within the NPS. Theoretical calculations suggest that the strengthened interactions between OOH intermediates and the dominant Ag(110) surfaces on NPS as revealed by an adsorption test reduce the activation energy for the rate determining step and thus accelerate the ORR. Due to the enhanced mass transfer and facile kinetics, the NPS exhibits excellent ORR activity and even outperforms the commercial Pt/C. Fascinating more, the service life of NPS is significantly extended through an in-situ regeneration process. The integration concept we demonstrate in this work shed new lights on the preparation of long-life functional materials with high performance in applications including but not limited to ORR.