A novel biochar from Ni-fed picochlorum eukaryotum for use as a high-performance enzyme-free electrochemical sensor of hydrogen peroxide

Abstract A novel method for the preparation of a homogeneous Ni-doped microalgae-based biochar material Ni-f-BC was established by combining biological feed from marine microalgae with soluble nickel salts (at an optimized concentration of 40 mg/L NiCl 2 ) and successive carbonization with programmed temperature pyrolysis under N 2 flow. A uniform distribution of Ni with an average size of approximately 10 nm was identified by scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), and energy-dispersive X-ray spectroscopy (EDS) analyses. Successively, a biochar-coated electrode (Ni-f-BC/GCE) was prepared by the ultrasonic dispersion of the biochar in N -methyl-2-pyrrolidone (1 mg/mL) onto a glassy carbon electrode. A sensitive H 2 O 2 sensor was developed based on our biochar materials with very good electrochemical performance, namely, with excellent electrocatalytic oxidation ability, a low detection limit of 0.39 μM in the physiological pH range (pH 7–8) and a rapid response time of 2.0 s. Notably, this sensor still exhibited good recovery rates of more than 90%, even in complex environments. Graphical Abstract