Hierarchical NiFe Hydroxide/Ni3N Nanosheet-on-Nanosheet Heterostructures for Bifunctional Oxygen Evolution and Urea Oxidation Reactions

The development of robust and cost-effective electrocatalysts for the oxygen evolution reaction (OER) and the urea oxidation reaction (UOR) is vital for promoting hydrogen generation from water electrolysis. Herein, we demonstrate a hierarchical coassembly of NiFe hydroxide nanosheets attached on Ni3N nanosheets [named NiFe(OH)x/Ni3N] as bifunctional electrocatalysts for the OER and the UOR. Thanks to the unique hierarchical nanosheet-on-nanosheet structures and strong interfacial interactions between NiFe(OH)x and Ni3N, NiFe(OH)x/Ni3N exhibits a remarkable OER activity with a low Tafel slope of 35 mV dec–1 and a small overpotential of 260 mV at 10 mA cm–2. Importantly, it also shows excellent electrocatalytic UOR activity, which exhibits a low potential of 1.36 V at 10 mA cm–2. This work may provide a broad avenue to develop hierarchical nanostructures as advanced electrocatalysts for efficient OER and UOR.