TiN nanosheet arrays on Ti foils for high-performance supercapacitance

A simple template-free method of preparing mesoporous TiN nanostructures directly on Ti foils is developed by combining hydrothermal, ion exchange and nitridation reactions. The as-prepared TiN nanosheet arrays on Ti foils can be directly used as an electrode without any subsequent processing, and are found to be a good capacitance material. The specific capacitance of the TiN nanosheets electrode measured at the current density of 0.5 A g(−1) reaches 81.63 F g(−1), and the capacitance retention is still 75% after 4000 cycles. The symmetric supercapacitor made up of two TiN nanosheet electrodes sandwiching a solid electrolyte (polyvinyl alcohol in KOH) shows a specific capacitance of 0.42 F cm(−3), and retains 77.6% of the capacitance even at the current density of 12.5 mA cm(−3).