Superb Pseudocapacitance Based on Three-Dimensional Porous Nickel Oxide Modified with Iridium Oxide

The need for environmentally compatible, less polluting, and more efficient energy systems has spurred extensive research into the development of batteries and other energy storage devices. Here, we report on a novel three-dimensional (3D) porous nickel modified with iridium oxide (IrO2) toward the design of a high-performance pseudocapacitor. The 3D porous nickel is grown directly onto a Ni plate via a facile electrochemical deposition method assisted by the simultaneously formed hydrogen bubble template. The effects of the electrodeposition time and the current density are systemically investigated, revealing that 3.0 A cm–2 and 150 s are the optimal conditions for the growth of the 3D porous nickel with the highest active surface area, which is subsequently modified with different quantities of IrO2. The electrodeposited 3D porous Ni network structure serves as a suitable template to accommodate the cast iridium chloride precursor and to anchor the formed IrO2 during the subsequent thermal treatment. The formed 3D porous NiIr(10%)Ox electrode exhibits high charge/discharge stability and a superb specific capacitance 1643 F g–1 at 1.92 A g–1, which is ∼175 times higher than the 3D porous NiO and over 95 times higher than the same amount of IrO2 deposited on a smooth Ni substrate.