Cathode catalysts based on porous carbon materials for low-temperature hydrogen-oxygen fuel cells

From 25.07.2017 till 30.06.2019
Grant holder: Tatiana Lastovina
Workers: Yulia Piminova

Low-temperature hydrogen-oxygen fuel cells (FCs) are promising chemical sources of current, allowing xhaustible energy sources while maintaining high efficiency. The undoubted advantage is the fact that water is the only by-product of the operation of such FCs. Hydrogen is often used as a fuel. Currently, such companies as Toyota, Honda and Hyundai already produce cars working on hydrogen. Since the end of 2014, sales of a hybrid car on FCs Toyota Mirai have started. However, the cost of FCs largely remains high due to the use of platinum-containing catalysts, whose usage is necessary due to the slow rate of cathodic and anodic reactions. Therefore, the task of reducing the content of platinum in catalysts for low-temperature FCs or replacing commercial Pt / C, PtM / C (M = Co, Ni, Cu, etc.) materials with Pt-free materials is topical. In recent years, the attention of the scientific community has been focused on catalytically active porous carbon materials doped with non-noble metal atoms (Fe, Co). Published to date studies indicate that such materials can achieve catalytic activity and stability being close to the platinum materials. The most common method for synthesizing carbon materials for the oxygen reduction reaction (ORR) is the sequential preparation of metal-organic framework (MOF) structures, doping them with iron and nitrogen atoms (less often, sulfur and phosphorus) by impregnation with appropriate precursors, and then their high-temperature treatment in a controlled atmosphere. The catalytic properties of the final material will be affected by a number of factors: the content of doping agents, the nature of the catalytically active sites, the temperature of the MOF treatment, the class of MOF used, etc. Under this project, catalytically active porous carbons will be produced by high-temperature treatment of ZIF (zeolitic imidazolate framework) materials of MOFs. ZIF-67, ZIF-68 and ZIF-69 structures will be used among others. Modified MOFs containing in their structure cobalt and zinc co-ions together with 2-methylimidazole linker will be obtained too. The sonochemical, solvotermal, microwave and electrochemical methods will be used to obtain the MOFs. The synthesized MOFs will be doped with iron atoms by impregnation with a solution of iron (II) acetate and with nitrogen atoms by impregnation with a solution of 1,10-phenanthroline followed with temperature treatment at 600-1100 degrees Celsius under argon atmosphere. The catalytic activity of the obtained materials will be evaluated in a three-electrode cell by cyclic voltammetry using a rotating disk electrode. The effect of doping with both iron and nitrogen on the electrochemical characteristics of catalytically active materials will be investigated. An important stage of the study will be an attempt to establish the mechanism for ORR and the nature of catalytically active centers. Materials characterized by the greatest catalytic activity and stability will be investigated in comparison with commercial platinum-containing catalysts.