Direct electrochemistry and electrocatalysis of horseradish peroxidase in α-zirconium phosphate nanosheet film

α-zirconium phosphate nanosheets (ZrPNS) derived via the delamination of layered α-zirconium phosphate (α-ZrP) have been proven to be efficient support matrixes for the immobilization of horseradish peroxidase (HRP). X-ray powder diffraction (XRD) results revealed that ZrPNS in HRP-ZrPNS film remained unorderly structured for the effect of HRP. Fourier transform infrared (FTIR) spectra results revealed that HRP remained the secondary structure in HRP-ZrPNS film. The direct electrochemistry of HRP was realized in HRP-ZrPNS film on a glassy carbon electrode (GCE), showing a pair of well-defined, nearly reversible cyclic voltammetry (CV) peaks for the HRP heme FeIII/FeII redox couple. The average surface concentration (Γ⁎) of electroactive HRP in HRP-ZrPNS film was estimated to be 1.35 × 10− 10 mol cm− 2, which indicated a high loading of enzyme molecules in HRP-ZrPNS film. Based on these, a third generation reagentless biosensor was constructed for the determination of hydrogen peroxide (H2O2). The response time of the biosensor was less than 3 s, and the linear response range of the biosensor for H2O2 was from 1.3 × 10− 6 to 1.6 × 10− 2 M with a correlation coefficient of 0.9997.