Bimetallic Ni-Co@hexacyano nano-frameworks anchored on carbon nanotubes for highly efficient overall water splitting and urea decontamination

Abstract

Efficient noble-metal-free electrocatalysts, particularly those employing the earth-abundant metals for their overall water-splitting and urea oxidation abilities, are crucial for energy conversion and storage. To this end, the present work demonstrates a facile synthetic route towards self-standing nanocubiods consisting of nickel-cobalt hexacyano frameworks, commonly known as Prussian blue (NC-PB)-analogue, anchored on carbon nanotubes (NC-PB@CNT) via an ion-exchange strategy. The overall water splitting performance of the NC-PB@CNT films was systematically investigated in an alkaline KOH electrolyte. The optimized NC-PB@CNT film is shown to provide an outstanding overall-water splitting performance with a low cell voltage of 1.66 Vat a rate of 50 mAcm(-2), along with an excellent long-term cell durability of more than 100 h. Furthermore, the addition of urea to the alkaline electrolyte is ascertained to decrease the cell voltage to 1.37 Vwith oxidation of urea at a rate of 50 mAcm(-2). The enhanced overall water splitting and urea oxidation (UOR) performance of the optimized NCPB@CNT electrode are assumed to arise from a synergistic effect between the carbon nanotubes and the framework structures, which enhances the catalytic active sites and provides a facile charge transport pathway between them.