A hollow urchin-like α-MnO 2 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 ·H2 O and (NH4 )2 S2 O8 , 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 (H2 O2 ) and dopamine (DA) at working potentials of -0.40 V and +0.4 V, respectively (both versus SCE). H2 O2 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 .H2 O and (NH4 )2 S2 O8 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.