Simultaneous water recovery and hydrogen production by bifunctional electrocatalyst of nitrogen-doped carbon nanotubes protected cobalt nanoparticles

Abstract

Cobalt nanoparticles encapsulated in nitrogen-doped carbon nanotubes (Co@NC) are obtained by a simple pyrolysis of Co-MOF (ZIF-67) for the bifunctional water recovery and hydrogen production. The results showed that calcination temperature of ZIF-67 significantly affected the morphology and catalytic performance. Wastewater are effectively recovered in the presence of the Co@NC and oxidant, which is promoted by anodic oxidation reactions. Co@NC as the cathode catalyst exhibited excellent hydrogen evolution reaction catalytic activity with a low onset potential of −51 mV (vs. RHE, current density of 0.5 mA/cm2), Tafel slope of 96.73 mV/dec and extraordinary long-term durability. Finally, as a proof of concept, a home-made two-electrode device employed Co@NC as both anode and cathode catalyst for continuous water recovery and simultaneous hydrogen production, which possesses the possibly applications in solving the environmental pollution and energy crisis.