Tunable Synthesis of N,C-Codoped Ti3+-Enriched Titanium Oxide Support for Highly Durable PEMFC Cathode

The hydrogen economy expansion triggered studies on the durability of hydrogen-powered proton-exchange membrane fuel cells (PEMFCs), which revealed that their performance is largely hindered by the degradation of cathode support. Herein, Ti3+-enriched N,C-codoped mixed-phase TiO2 nanoparticles featuring a reduced (compared to that of pristine TiO2) band gap and containing Ti3+ ions, oxygen vacancies, and Ti–X bonds (X = O, OH, N, C) were synthesized as a durable PEMFC cathode support by annealing. The extent of doping was controlled by adjustment of dopant (urea) loading, while the abundance of defect sites resulted in an enhanced metal–support interaction (i.e., Pt–Ti bonding) for Pt/N,C-codoped TiO2, as confirmed by the shift of the most prominent Pt0 peak of Pt/N,C-codoped TiO2 to lower binding energies (by 0.96 eV) relative to that of Pt/C. Electrochemical performance testing of the above support revealed its high activity for the oxygen reduction reaction and elevated durability. In particular, a maximum power density decrease of only 4% (cf. 52% for Pt/C under the same conditions) and high durability under PEMFC operation conditions were observed in a single-cell test. Thus, the presented results highlight the great potential of TiO2 as an electrocatalyst support, paving the way to the fabrication of high-performance hydrogen fuel cells and contributing to the establishment of a hydrogen society.