Carbon\nNitrogen Nanotubes as Efficient Bifunctional Electrocatalysts for\nOxygen Reduction and Evolution Reactions

Abstract

Oxygen reduction and evolution reactions\nare essential for broad range of renewable energy technologies such\nas fuel cells, metal-air batteries and hydrogen production through\nwater splitting, therefore, tremendous effort has been taken to develop\nexcellent catalysts for these reactions. However, the development\nof cost-effective and efficient bifunctional catalysts for both reactions\nstill remained a grand challenge. Herein, we report the electrocatalytic\ninvestigations of bamboo-shaped carbon nitrogen nanotubes (CNNTs)\nhaving different diameter distribution synthesized by liquid chemical\nvapor deposition technique using different nitrogen containing precursors.\nThese CNNTs are found to be efficient bifunctional electrocatalyst\nfor oxygen reduction and evolution reactions. The electrocatalytic\nactivity strongly depends on the nanotube diameter as well as nitrogen\nfunctionality type. The higher diameter CNNTs are more favorable for\nthese reactions. The increase in nanotube diameter itself enhances\nthe catalytic activity by lowering the oxygen adsorption energy, better\nconductivity, and further facilitates the reaction by increasing the\npercentage of catalytically active nitrogen moieties in CNNTs.