Hierarchical Co-N microballs with heterostructure exhibiting superior electrochemical properties for water splitting and reduction of I3-

Metal nitrides are a new type of electrocatalysts applied in energy storage and conversion systems. In this report, hierarchical cobalt nitride micros balls with heterostructure are prepared through nitridation of Co(OH)(CO3)(0.5)center dot 0.11H(2)O counterparts. The microballs are composed of nanowires, which enchase nanoparticles with heterostructure in terms of Co5.47N/Co3N. The catalyst presented here exhibits a high power conversion efficiency of 7.3% for reduction of I-3(-), comparable to that of 7.6% for platinum-based catalysts. In alkaline electrolyte (1 mol L-1 KOH), only 55 and 290 mV of overpotentials are required to achieve a current density of 10 mA cm(-2) for hydrogen evolution and oxygen evolution reactions, respectively. The superior electrochemical performance of the catalyst is attributed to the synergistic effect resulting from Co5.47N/Co(3)Nheterostructure. (C) 2019 Elsevier B.V. All rights reserved.