Porous Dual‐Layered MoO_<i>x</i> Nanotube Arrays with Highly Conductive TiN Cores for Supercapacitors

Abstract Porous dual‐layered molybdenum oxide (MoO x ) nanotube arrays (NTAs) with highly conductive titanium nitride (TiN) cores (MoO x /TiN/MoO x NTAs) are fabricated by depositing MoO x on porous TiN NTAs produced by nitriding as‐anodized TiO 2 NTAs on Ti foils. The highly conductive TiN facilitates electron transfer and the porous MoO x wall allows the electrolyte to permeate the nanotubes readily, maximizing the active sites of the MoO x electroactive material to improve the specific capacitance and rate capability. The coaxial MoO x /TiN/MoO x NTA electrode shows a high specific capacitance of 97 mF cm −2 (323 F g −1 ) at a current density of 1 mA cm −2 , and 60 % capacitance is retained when the current density is increased 20 times. A symmetrical device based on the MoO x /TiN/MoO x NTA electrode exhibits a capacitance as high as 24 F cm −3 (based on the volume of MoO x /TiN/MoO x NTAs) and no significant decay is observed after charging/discharging for 10 000 cycles.