高分散Co-N-C涂层电极制备及其产H_(2)O_(2)效能

Preparation of highly dispersed Co-N-C coating electrode and its efficiency of H_(2)O_(2) production

为了研究电极表面Co-N-C催化剂的分散性和电化学工艺参数对产H_(2)O_(2)机制与效能的影响,以石墨板为基底,Co-N-C催化剂为涂层制备石墨基高分散Co-N-C涂层电极。通过扫描电子显微镜、X线衍射、循环伏安扫描和X线光电子能谱等手段对制备的Co-N-C催化剂及涂层电极进行微观结构和电化学表征,改变石墨粉与Co-N-C的质量比来控制负载量,考察不同Co-N-C负载量涂层电极对O_(2)的催化还原活性和不同工艺条件下的产H_(2)O_(2)效能,并对影响机制进行深入探究。结果表明:Co-N-C催化剂被均匀负载到石墨板表面,其中Co-N-C-20(Co-N-C与石墨粉的质量比为1∶20)涂层电极具有较好的分散性和最高O_(2)的二电子还原催化活性。酸性条件、合适的电流密度和O_(2)曝气量有助于O_(2)的二电子还原反应生成H_(2)O_(2),减少H2O_(2)继续被还原和分解。在优化工艺条件下反应80 min,Co-N-C-20电极产H_(2)O_(2)的累积浓度达到291.3 mg/L,电流效率为52.66%。

To study the effect of Co-N-C catalyst dispersion on the electrode surface and the effect of electrochemical process parameters on the mechanism and efficiency of H_(2)O_(2) production,graphite-based highly dispersed Co-N-C coating electrodes were prepared with graphite plate as the substrate and Co-N-C catalyst as coating.The microstructure and electrochemical characterization of the prepared Co-N-C catalyst and coating electrodes were carried out by scanning electron microscopy,X-ray diffraction,cyclic voltammetry scanning and X-ray photoelectron spectroscopy.The Co-N-C loading was controlled by changing the mass ratio of graphite powder to Co-N-C,the catalytic reduction activity of the coated electrodes with different Co-N-C loadings on O_(2) and the efficiency of H_(2)O_(2) production under different process conditions were investigated,and the influence mechanism was further explored.Results showed that the Co-N-C catalyst was uniformly loaded on the surface of the graphite plate,and the Co-N-C-20 coated electrode(mass ratio of Co-N-C to graphite powder of 1∶20)had good dispersion and the best catalytic activity for two-electron reduction of O_(2).Acid conditions,appropriate current density and O_(2) aeration were helpful for the two-electron reduction of O_(2) to generate H_(2)O_(2),reducing the further reduction and decomposition of H_(2)O_(2).After reaction for 80 min under the optimized conditions,the cumulative concentration of H_(2)O_(2) produced by the Co-N-C-20 electrode reached 291.3 mg/L,and the current efficiency was 52.66%.