Nitrogen-doped carbon nanotubes embedded with nitrogen-doped carbon black anchoring Pd nanocrystals to boost ethanol electrooxidation

Abstract

Seeking and engineering superior supporting materials is a powerful strategy to rationally design electrocatalysts with both high activity and robust durability towards ethanol oxidation reaction (EOR). Accordingly, herein, nitrogen-doped carbon nanotubes embedded with nitrogen-doped carbon black (NCB@NCNTs) anchoring surface-clean Pd nanocrystals (Pd/NCB@NCNTs), possessing a prominent three-dimensional network structure and adequate nitrogen-containing functional groups, were fabricated through a mild hydrothermal process followed by a surfactant-free chemical reduction. Oxidized carbon nanotubes (OCNTs), oxidized carbon black (OCB) and ethylenediamine (EDA) were used as precursors to acquire NCB@NCNTs. EDA not only serves as a nitrogen source to realize nitrogen doping but also acts as an important structural modifier to construct the firm cross-linked three-dimensional network structures through the strong hydrogen bonds. The obtained Pd/NCB@NCNTs exhibit exceptionally improved electrocatalytic activity, fast kinetics and robust durability as well as stability compared with the commercial Pd/C towards the EOR, due to the prominent roles of NCB@NCNTs with a unique three-dimensional network architecture and abundant nitrogen-containing functional groups. Specifically, the electrocatalytic EOR properties of Pd/NCB@NCNTs-2 with an optimal OCB/OCNT mass ratio of 1/4 is optimal among all prepared electrocatalysts and commercial Pd/C. This work presents a new design of a carbon-based material to fabricate highly active and durable catalysts for fuel cells and beyond.