Partially Reduced TiO2 Aerogel as a Catalyst of Oxygen Reduction Reaction in Alkaline Solution

A resorcinol-formaldehyde/titanium oxide (RF/TiO2) aerogel was synthesized via an acid-catalyzed sol-gel process followed by CO2 supercritical drying. After the thermal treatment of the RF/TiO2 aerogel, the partially reduced TiO2 aerogel (PRTA) was prepared as a catalyst for oxygen reduction reaction (ORR). Magnéli phase (Ti4O7) and anatase with oxygen vacancies were formed in PRTA. The specific surface area and the pore volume of PRTA were 637 m2 g−1 and 1.72 cm3 g−1, respectively. RF-derived carbon, TiO2(a)/TiO2(r), and TiO2(a) were also prepared to estimate the origin of ORR activity. The Eonset, E1/2, and Jlimit were 0.75 V, 0.65 V, and 3.33 mA cm−2, respectively. Its stability outperformed Pt/C. This preparation method is inspiring for preparing the Magnéli phase with a better pore structure. A partially reduced TiO2 aerogel catalyst with high specific surface area and high pore volume was synthesized by the sol-gel method, CO2 supercritical drying and in-situ carbothermal treatment. The sample showed appealing ORR catalytic activity due to the formation of Ti4O7 (Magnéli phase) and anatase, which contains abundant oxygen vacancies and structural defects.