A newly prepared Ni(OH)2@Cr(OH)3 nanohybrid for its bioelectrocatalysis

• The Ni(OH)2@Cr(OH)3 nanohybrid was prepared by a simple one-step way.
• The doped CrIII decreased the Ni(OH)2@Cr(OH)3 hybrid to nanoscale.
• Ni(OH)2@Cr(OH)3 satisfactorily electrocatalyzed glucose and cysteine oxidations.
• The bioelectrocatalytic performances of the nanohybrid was improved by CrIII.

A simple one-step method was successfully developed to prepare stable nanosized Ni(OH)2@Cr(OH)3 hybrid particles by just adding NaOH to a mix solution containing Ni(NO3)2 and Cr(NO3)3 at room temperature. In contrast, under the exact same conditions, flocculent Ni(OH)2 or Cr(OH)3 precipitate was obtained after the addition of equivalent NaOH in a solution containing same amount of Ni(NO3)2 or Cr(NO3)3 as in the mix solution. The interaction between Ni(II) and Cr(III) ions was believed to make major contribution to the formation of stable Ni(OH)2@Cr(OH)3 nanohybrid without aggregation to large-size particles. The prepared Ni(OH)2@Cr(OH)3 hybrid nanoparticles were well characterized by the scanning electron microscopy (SEM), the transmission electron microscopy (TEM), X-ray diffraction (XRD), and electrochemical measurements with results showing uniform size, smooth surface, good monodispersibility, fast electron transfer rate as well as promising electrocatalytic properties toward glucose (Glu) and cysteine (Cys) oxidation. The presence of a small amount of Cr(OH)3 in the composite not only improved the stability and monodispersibility of the Ni(OH)2@Cr(OH)3 hybrid particles, decreased their size to nanoscale, but also exerted positive effect to the electrochemical properties of the obtained Ni(OH)2 based nanomaterials like the electron transfer rate and the electrocatalytic activity. Satisfactory electrocatalytic performances of the Ni(OH)2@Cr(OH)3 nanohybrid toward Glu and Cys oxidations were achieved, respectively, in certain concentration ranges with acceptable detection limits and correlation coefficients, suggesting the potential facilitation of electrocatalysis toward other small molecules by the newly prepared Ni(OH)2@Cr(OH)3 nanohybrid.