Porous flower-like nickel nitride as highly efficient bifunctional electrocatalysts for less energy-intensive hydrogen evolution and urea oxidation

Finding a suitable replacement for the high potential of anodic water electrolysis (oxygen evolution reaction (OER)) is significant for hydrogen energy storage and conversion. In this work, a simple and scalable method synthesizes a structurally unique Ni3N nanoarray on Ni foam, Ni3N-350/NF, that provides efficient electrocatalysis for the urea oxidation reaction (UOR) that transports 10 mA cm(-2) at a low potential of 1.34 V. In addition, Ni3N-350/NF exhibits electro-defense electrocatalytic performance for hydrogen evolution reaction, which provides a low overpotential of 128 mV at 10 mA cm(-2). As proof of concept, all-water-urea electrolysis measurement is carried out in 1 M KOH with 0.5 M Urea with Ni-3 N-350/NF as cathode and anode respectively. Ni3N-350/NF parallel to Ni3N-350/NF electrode can provide 100 mA cm(-2) at a voltage of only 1.51 V, 160 mV less than that of water electrolysis, which proves its commercial viability in energy-saving hydrogen production. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.