Well-matched core–shell NiO@LaMnO3/MWCNTs p-p homotype heterojunction for ascorbic acid detection

A novel core–shell p-p homotype heterojunction based on NiO@LaMnO 3 and multi-walled carbon nanotubes (NiO@LaMnO 3 /MWCNTs) has been designed and synthesized via electrostatic self-assembly method. The phase compositions and morphology were verified by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM). A series of electrochemical tests showed that NiO@LaMnO 3 /MWCNTs modified electrode had a magnifying effect on the electrochemical response signal of ascorbic acid (AA) detection. The current response is linearly increased in the range of 2.60–36.44 μmol/L with the linear regression equation being I (μA)  = 0.5902 C (μmol/L) + 1.4407 (R 2  = 0.9909), and the detection limit (S/N = 3) being 2.41 μmol/L. Moreover, NiO@LaMnO 3 /MWCNTs/GCE electrochemical sensor presented satisfying selectivity, stability, repeatability, and can be used to analyze the AA concentration in real daily drinks. The relatively excellent electrocatalytic activity should be attributed to high electroactive surface area, well-matched core–shell structure and synergetic effect of p-p homotype heterojunction. This work offer applicable guidelines for the design of core–shell p-p heterojunction electrode materials for the application of electrochemical sensor.