Charge polarization-dependent activity of catalyst nanoparticles on carbon nitride nanotubes for hydrogen generation

Abstract

We demonstrate that catalyst nanoparticles attached to carbon nitride nanotubes (CNNTs) show superior catalytic activity for hydrogen generation from aqueous solutions. The calculated natural bonding orbitals show quite different charge polarizations for different catalysts attached to CNNTs; Co and Ni atoms attached to CNNTs are more positively polarized than Pt when they interact with NaBH(4) and H(2)O. Our experiments prove that the increased positive charges for Co and Ni result in a greater ability to attract hydride anions, thus improving the hydrogen generation rate. For example, Co catalysts attached to CNNTs show the highest hydrogen generation rate, up to 10 kg hydrogen per hour per 1 kg catalyst, while Pt is about 3 times less effective. It should therefore be feasible to use cheap metals such as Co for generating hydrogen from aqueous solutions for automobile applications.