The Performance Study Of Electrocatalysis Reduction Of Carbon Dioxide Based On Silver Electrode

Carbon dioxide is an important greenhouse gas, and many scientists have proposed a number of ways to reduce its content in the atmosphere. Converting carbon dioxide into energy is the most attractive way for human being because of its precious product. Electro-catalytic reaction has become hot in carbon dioxide catalysis study, because it has mang advantanges such as easy-controlling, recycling, producing no more carbon dioxide and easy modularity. Sliver has a high product selectivity, relatively low cost, high chemical stability, environmentally friendly compared with other electro-catalytic materials. In this paper, three-electrode system was set up to study the electrical properties of silver catalytic with different silver content and silver plating in different processes for reducing carbon dioxide. Ionic liquids system and "anodized and then restore" process was also studied in reducing carbon dioxide.Commercial 925 silver, 950 silver, 999 silver and 9999 silver were tested and found that the first two have failed to reach its content which the label required. Respectively, the four kinds of silver were acted as working electrode, Pt sheet as the counter electrode and Ag / Ag Cl electrode with saturated KCl as the reference electrode, 0.5mol/L potassium bicarbonate as electrolyte. Testing for their electrical performance catalytic reduction of carbon dioxide, the results showed that 950 silver’s overpotential was the lowest(-1.1V) and the 9999 silver was the highest(-1.3V). At the same electrical potential, current density of 950 silver were higher than the others. In the CO Faraday efficiency, 9999 was significantly higher than the other silver(highest at 60%). Therefore, when Ag was chosen as electrocatalytic for the reduction of carbon dioxide, the purity of Ag should be high.In the cyanide-free plating system, copper was used as substrate, 5,5-dimethyl hydantoin as complexes, Silver nitrate as main salt. Different kinds of silver plating were prepared by controlling the current density, plating time and the addition of pyridine. SEM results showed that the coating can be refined with the addition of pyridine. XRD results showed that under a special process,(220) plane and the(311) plane were preferred. Combined with the result of Faraday efficiency,(220) plane and the(311) plane could promote the Faraday efficiency of CO(highest at 70%).BMIM-BF4 ionic liquids system could slightly increase the current density and significantly improved the efficiency of CO Faraday efficiency(highest at 90%) comparing with potassium bicarbonate system. But its high cost and low stability would restrict its development determinants. As for the "anodizing re-reduction" technology, the overpotential was decreased after the treatment of 0.3V(-1.1V), while identical after the treatment of 0.6V(-1.3V). The current density and Faraday efficiency was significantly increased after the treatment(highest at 80%), which implied that deserved further research.