Increasing the number of active sites of polymer-assisted carbon nanotubes/Ag nanoparticles for enhanced oxygen reduction

Increasing the number of electroactive sites to enhance catalytic activity is by far the best approach for enhancing the oxygen reduction reaction; however, the development of a catalyst with high electrochemical performance and long-term stability remains a significant challenge because of the weak binding energy of oxygenated species. Herein, we report the fabrication of an extended Ag nanoparticle network on a defect-rich carbon nanotube (CNT) ternary composite, CNT@pPPD-Ag, derived from polyparaphenylenediamine (pPPD) with a porous crystalline framework that enhances the edge-rich N-species-decorated carbon nanotubes. The N-bridged-polymer/CNT composite facilitates the aligned dispersion of Ag nanoparticles anchored at the low coordination sites, increases the surface area and pore size volume, and exposes effective CNT-N-Ag active sites for enhanced oxygen absorption to convert O-2 into H2O. In addition, the reduced electron delocalization around the Ag atoms due to the N-species enhances the charge interaction between the neighboring N and Ag atoms, leading to the strengthening of the interaction with the adsorbed oxygen species, thereby increasing the intrinsic activity of each electroactive site. In this work, CNT@pPPD-Ag composite explored with remarkable low onset potential (-0.041 V) and limiting current density (-5.80 mA cm(-2)) in an alkaline environment, and far exceeds the performance of expensive Pt/C catalysts.