A hollow urchin-like α-MnO2 as an electrochemical sensor for hydrogen peroxide and dopamine with high selectivity and sensitivity.

A hollow urchin-like α-MnO2 material has been synthesized by a hydrothermal method starting from MnSO4·H2O and (NH4)2S2O8, and by using silver(I) as the catalyst. It has a hollow morphology with diameters of 5-6 μm and consists of densely aligned nanowires, with a 30-40 nm width and a 1.5 μm length. The diameter of the cavities and the thickness of the shell are about 1.2 μm and 300 nm, respectively. The material was placed on a glassy carbon electrode (GCE), and electrochemical experiments showed the respective sensor to possess good stability and reproducibility. The modified GCE displays response to both hydrogen peroxide (H2O2) and dopamine (DA) at working potentials of -0.40 V and +0.4 V, respectively (both versus SCE). H2O2 can be detected with an 80 nM detection limit, and DA with a 12 nM detection limit (at S/N = 3). Graphical abstract Schematic presentation of synthesis of a hollow urchin-like α-MnO2, which taking MnSO4.H2O and (NH4)2S2O8 as raw materials and was further used to construct an electrocatalytic sensor for hydrogen peroxide and dopamine with low detection limit, desirable selectivity and sensitivity.