Yan Jia

Electrochemical sensing of ethylenediamine based on cuprous oxide/graphene hybrid structures

An electrochemical sensor based on in situ synthesized Cu2O microparticles–Cu2O nanowires–graphene (Cu2O MPs–Cu2O NWs–graphene) composite for sensitive detection of ethylenediamine (EDA) is reported. X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, field emission transmission electron microscopy, and energy-dispersive X-ray spectroscopy were utilized to characterize the composition and morphology of the composite. The electrochemical behaviors of EDA at the Cu2O MPs–Cu2O NWs–graphene composite modified electrode were investigated by electrochemical impedance spectroscopy, cyclic voltammetry, and linear sweep voltammetry. The electrochemical sensor exhibited excellent analytical performance for EDA detection with low detection limit of 3.83xa0×xa010−5 M (S/Nxa0=xa03) and a reproducibility of 1.1xa0% relative standard deviation. The modified electrode exhibited a rapid response to EDA within 5xa0s and the amperometric signal showed a good linear correlation to EDA concentration in a broad range from 0.25 to 1.25xa0mM with a correlation coefficient of Rxa0=xa00.99699. The superior electrochemical performances of Cu2O MPs–Cu2O NWs–graphene composite are attributed to their peculiar composite structure and the synergistic effects between Cu2O MPs–Cu2O NWs and graphene [Huang et al., Sens Actuators B 178:671–677, 2013; Luo et al., Anal Chim Acta 709:47–53, 2012].

X-ray diffraction and raman spectroscopy characterization of isotropic pyrocarbon obtained by hot wall chemical vapor deposition

Varying the flow rate of natural gas from 50 to 80 to 120 l/h, isotropic pyrocarbon produced by hot wall chemical vapor deposition at 1000 °C were examined by X-ray diffraction and Raman spectroscopy. The X-ray data were evaluated by Scherrer equation, and the intensity ratio of D to G band derived from Raman data was used to evaluate the lateral extension of isotropic pyrocarbon. The experimental results show that the d002-spacing of isotropic pyrocarbon decreases from 0.3499 nm to 0.3451 nm, while the stack height increases from 6.5 to 8.4 nm with the increase of flow rate of natural gas. The intensity ratio of D to G band and lateral extension of isotropic pyrocarbon increases with natural gas flow rate increasing. After heat treatment, all the crystallite parameters (stack height, lateral extension, and d002-spacing) decrease, indicating the improvement of the arrangement of the basic structural units of isotropic pyrocarbon.