Silver nanofibers with controllable microstructure and crystal facet as highly efficient and methanol-tolerant oxygen reduction electrocatalyst

Self-support silver nanofibers with excellent electrocatalytic performance for oxygen reduction reaction (ORR) are successfully fabricated through a hybrid method combining an electrospinning process with an electroplating technique. This nanofiber-based catalyst demonstrated superior long-term stability and an unusually high methanol-tolerant effect that its ORR activity was enhanced, instead of lessened in 3 M methanol. The impact of microstructure and crystal facet on ORR activity is examined through quantifying the performance of the catalysts by electrochemical measurements. Through tuning the synthesis parameters, the onset potential, half-wave potential, and peak potential of 1.041 V, 0.848 V, and 0.864 V are achieved for the silver nanofibers with thorny structure, even superior to those of commercial Pt/C catalyst. Such excellent performance is attributed to two major factors, the micro morphology, i.e. thorn-on-fiber structure, and the crystal facet. The special thorny structure leads to the accumulation of electrons on the tip to act as highly active sites and better confinement of the oxygen between thorns, while the high ratio of (110) facets on the tip favors high catalytic activity. This kind of low-cost silver nanofiber-based catalyst exhibits a highly beneficial prospect as a potential alternative catalyst for oxygen reduction reaction.