  Highly active, durable and cost-effective electrocatalysts for water
oxidation to evolve oxygen gas hold a key to a range of renewable energy
solutions including water splitting and rechargeable metal-air batteries. Here,
we report the synthesis of ultrathin nickel iron layered double hydroxide
nanoplates on mildly oxidized multi-walled carbon nanotubes. Incorporation of
Fe into the nickel hydroxide induced the formation of NiFe-layered double
hydroxide. The nanoplates were covalently attached to a network of nanotubes,
affording excellent electrical wiring to the nanoplates. The ultra-thin Ni-Fe
layered double hydroxide nanoplates/carbon nanotube complex was found to
exhibit unusually high electro-catalytic activity and stability for oxygen
evolution and outperformed commercial precious metal Ir catalysts.
