Hollow Loofah-Like N, O-Co-Doped Carbon Tube for Electrocatalysis of Oxygen Reduction

Designing a highly active doped-carbon-based oxygen reduction reaction (ORR) electrocatalyst with optimal stability is a must if large-scale implementations of fuel cells are to be realized. Developing controllable doping strategies is essential for achieving highly active catalysts. Herein, a facile doping strategy is developed by designing a precursor material with unique core-shell nanostructure, whereby the Materials Institute Lavoisier (MIL) metal-organic framework (MOF) and polyaniline are core and shell components, and serving as oxygen and nitrogen precursors, respectively. A novel hollow loofah-like carbon tube (HLCT) catalyst is derived from precursor material with controllable heteroatom-doping concentrations through modulating the mass ratio of MOF/aniline. The optimal HLCT-1/2 catalyst, with a MOF/aniline mass ratio of 1/2, exhibits excellent ORR activity and stability in an alkaline medium. Remarkably, the half-wave potential (0.88 V) and the current density (4.35 mA cm(-2)) at 0.85 V of HLCT-1/2 catalyst surpass that of commercial Pt/C. Such superior catalytic properties can be attributed to the high specific surface area and abundant active sites of loofah-shape carbon tubes. Moreover, the O dopant modulates the content and distribution of N species, leading to the enhanced adsorption strength of oxygen molecules on catalyst surface, promoting the activation of oxygen, and thus achieving higher electrocatalytic activity.