CoNiO2/TiN-TiOxNy composites for ultrahigh electrochemical energy storage and simultaneous glucose sensing

We report a rational growth of functional CoNiO2/TiN-TiOxNy composites on flexible Ni foam for ultrahigh energy storage with fast charging capability and simultaneous non-enzymatic glucose detection. The TiN-TiOxNy intermediate layer provides both fast electron transport and a uniform growth substrate for polycrystalline mesoporous CoNiO2 NWs, at the same time preventing corrosion of the Ni substrate. Ultrahigh areal pseudocapacitance of 3181 and 2763 F g(-1) (or 3.36 and 2.83 F cm(-2)) is obtained from the CoNiO2/TiN-TiOxNy composite at current densities of 2 and 10 mA cm(-2), respectively; these values are substantially better than those obtained from the plain CoNiO2 NWs at the same current densities. Furthermore, the CoNiO2/TiN-TiOxNy composite exhibits high flexibility and cycling stability, and can be charged up to 1.64 F cm(-2) within 9 seconds at a high current density of 100 mA cm(-2). Moreover, after being fully charged, the CoNiO2/TiN-TiOxNy composite-based pseudocapacitors can maintain an extended discharge time of hundreds to thousands of seconds, and are demonstrated as power-free sensors for real-time electrochemical detection of glucose, with a detection limit of similar to 1 mu M.