(1) Preparation of Ti4O7: As a catalyst support, it needs to have a large specific surface area, and the difficulty lies in this. The specific surface area of Ti4O7 synthesized by single step method is very small. The specific surface area of multistep synthesis was 140m2/g.
(2) Catalyst performance: The activity and durability of Ti4O7 supported catalyst is better than that of Pt/C catalyst. After the formation of Ru-Pt core-shell structure, the Ti4O7 supported catalyst not only has CO resistance, but also improves the catalyst activity.
(3) Pt: The combination of Pt and Ti4O7 reduces electron conduction, and the morphology of Pt on Ti4O7 can be improved by increasing Pt load.
1. Preparation of Ti4O7 carrier with high surface area
(1) To synthesize Ru/ti4o7, 79.6mg(0.25mmol) of ruthenium Ru(acac)3 and 1782.3mg of titanium dioxide TiO2 were ground together in mortar until a uniform light pink color was obtained. This mixture is then placed in an alumina crucible with a lid and purified in a tube furnace at room temperature with a mixture of H2 and Ar at a ratio of 1:1 for 4 hours, followed by heat treatment at 5℃/min increments. When the temperature reached 1050℃, the sample was kept at this temperature for 6h, and then was reduced to room temperature at a rate of 5℃/min. After this cycle is complete, the tube containing the sample is cleaned with Ar to remove any H2 for safety reasons. In this process, a Ru nucleus supported by ti4o7 particles is formed and ready for the next step of synthesis.
The difficulty lies in the preparation of Ti4O7 with high surface area, which requires nano-sized carrier particles. Microwave method is conducive to controlling particle diameter, which is briefly introduced below.
(2) The precursor ti4o7 was prepared by placing rutile titanium-dioxide nanoparticles and polyethylpyrrolidone PVP K30 in pure water under ultrasonic irradiation for 30 minutes. The precursor was heated by 2.45GHz microwave at 950°C for 30 min to prepare ti4o7 nanoparticles.
2. Pt nanoparticles supported by carrier
The Ru/Ti4O7 core powder formed above was placed in a flask containing 33.82mgPtCl2(0.13mmol) and 127mL tri ethylene glycol (TEG)(0.002M) and stirred continuously at room temperature. The flask is then placed under microwave irradiation for 5min. After this irradiation, the flask is removed and cooled at room temperature for at least 2 hours. The sample is then placed in a centrifuge to remove the TEG solvent. The solids were cleaned with clean ethanol and centrifuged for 20min to further remove the TEG residue. Following these processes, the resulting catalyst is vacuum-filtered and dried overnight in an oven at 100℃. The dried sample is then ground to produce the final catalyst powder (Ru@Pt/Ti4O7).
3. Make membrane electrodes
Preparation of membrane electrode: uniform catalyst ink containing Ru@Pt/ti4o7 catalyst, 2-propanol, nano ionomer and deionized water. The catalyst ink is then sprayed onto an extra tetrafluoroethylene transfer sheet to form a catalyst layer, which is then transferred to a film on which a sheet of carbon paper is placed for hot pressing.