CoOOH nanosheet electrodes: Simple fabrication for sensitive electrochemical sensing of hydrogen peroxide and hydrazine

Cobalt oxyhydroxide, CoOOH, nanosheets were prepared via a surface alkaline treatment of cobalt foil at room temperature without using templates and catalysts. The morphology, chemical composition and structures of the nanosheets were characterized by XRD, FTIR and Raman spectroscopy, FESEM and TEM. These oriented and nanostructured arrays can be used directly as electrodes, thus simplifying the electrode fabrication process, as well as offering advantages such as enhanced electrode–electrolyte contact area, minimum diffusion resistance and direct active material–current collector connection for fast electron transport. The electrode was used as an electrochemical sensor towards non-enzymatic detection of hydrogen peroxide and hydrazine in alkaline solution. The amperometric detection of H2O2 and N2H4 was carried out at low potential (0 V and 0.1 V). At 0.1 V, the amperometric signals are linearly proportional to H2O2 concentration up to 1.6 mM (R2=0.995), showing a detection limit (S/N=3) of 40 μM and a high sensitivity of 99 μA mM−1 cm−2. For N2H4, the amperometric signals are linearly proportional to concentration up to 1.2 mM (R2=0.99), showing a detection limit (S/N=3) of 20 μM and a high sensitivity of 155 μA mM−1 cm−2 at 0.1 V.

► Synthesis, formation mechanism and characterizations of CoOOH nanosheets.
► Direct use of the as-synthesized materials as enzymeless amperometric sensors.
► High sensitivity towards detection of hydrogen peroxide and hydrazine at low applied potentials (0 and 0.1 V).