Porous Bi electrode fabricated using facile electrochemical deposition process showed as CO2 electro-catalyst that was highly selective toward formate formation. The morphology of the Bi electrode was investigated through scanning electron microscopy (SEM), and their structure was characterized via x-ray photoelectron spectroscopy (XPS) and x-ray diffraction (XRD). The as-prepared polycrystalline Bi electrode was formed of 3 porous layers with different pore sizes, and its surface was slightly oxidized. The electro-catalytic activity and stability of the Bi electrode with regard to CO2 electro-reduction in aqueous solutions was then assessed. In contrast to planar Bi electrode synthesized with conventional electroplating method, the porous Bi electrode showed 0.2 V lower onset potential and higher current, which were attributed to the highly active surface area and its special morphology. And the porous Bi electrode had a wider range of potential at which the CO2 conversion efficiency exceed 90% than the planar Bi electrode. To further characterize the electrochemical behavior, electrochemical active surface area (ECSA), electrochemical impedance spectroscopy (EIS), and tafel were also carried out in this study. Monovalent ion effect, such as alkaline metal ion and halide ion, were also studied in this experiment. Furthermore, the as-synthesized porous Bi electrode was tested in CO2 saturated artificial sea-water, and it showed stable current with 10 mA/cm2 and over 80% CO2 conversion efficiency.

Facile synthesis of highly porous Bi electrocatalysts for high efficiency formate production from CO2 in various electrolytes

2019 Fall National Meeting

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