Cu-doped titanium suboxide fuel cell catalyst support prepared by sol-gel method: Unveiling the role of Cu as a lone dopant

• Sol-gel synthesis of Cu-doped titanium suboxide (TOC) with a high surface area. • Cu as a lone dopant effectively reduces the band gap but is susceptible to leaching. • Strong metal support interaction helps anchor Pt catalyst particles TOC support. • Pt/TOC has higher stability and oxygen reduction reaction activity compared to Pt/C. In this study, we demonstrate a facile synthetic approach for a bottom-up sol-gel method for the preparation of a non-carbonaceous Cu-doped Ti 4 O 7 suboxide (TOC) fuel cell catalyst support. In addition, we seek to achieve a better understanding of the role of Cu as a dopant and reveal its contribution to activity and stability in Pt/TOC during the oxygen reduction reaction (ORR) and corresponding accelerated stress tests (ASTs). The Pt/TOC catalyst showed an enhanced activity and stability over commercial Pt/C due to the strong metal support interaction between TOC and Pt. This enabled the catalyst to retain its oxygen reduction performance after extended load cycling tests. Thus, Cu as a lone dopant was effective in promoting oxygen vacancies and greatly reduces the electronic bandgap, however Cu was prone to leaching after repeated cycling protocols. Finally, we also observed a relatively decreased stability compared to our previous dual-doped systems, highlighting the importance of incorporating a secondary dopant species for synergistic effects in stability and activity.