Experimental and theoretical studies on the effect of functional groups on carbon nanotubes to its oxygen reduction reaction activity

Functionalization of carbon nanotubes (CNTs) has been proven to be an effective method to modulate their properties including electrocatalytic activity. Here, we report the catalytic properties of CNTs modified with various functional groups in the oxygen reduction reaction (ORR). Experimental data show that ORR activity of CNTs is enhanced markedly with increasing content of carboxyl groups, and MWNT-COOH sample display the highest current density and most positive onset potential among the studied catalysts. Remarkably, the functionalized CNTs exhibit excellent long-time stability and tolerance towards alcohols. Both experimental and theoretical results suggest that the deprotonated state of carboxyl groups promote the ORR electrocatalytic performance of CNTs in an alkaline electrolyte