Effects of Transition Metal Doping in Pt/M-TiO 2 (M= V, Cr, and Nb) on Oxygen Reduction Reaction Activity

Abstract

High cost and low durability are unresolved issues that impede the commercialization of proton exchange membrane fuel cells (PEMFCs). To overcome these limitations, Pt/TiO2 is reported as an alternative electrocatalyst for enhancing the oxygen reduction reaction (ORR) activity and/or durability of the system. However, the low electrical conductivity of TiO2 is a drawback that may be addressed by doping. To date, most reports related to Pt/doped-TiO2 focus on changes in the catalyst activity caused by the Pt-TiO2 interaction (metal-support interaction), instead of the effect of doping itself; doping is merely considered to enhance the electrical conductivity of TiO2. In this study, we discuss the variation in the electronic fine structure of Pt caused by the dopant, and its correlation with the ORR activity. More extensive contraction of the Pt lattice in Pt/M-TiO2 (M = V, Cr, and Nb) relative to Pt/TiO2 and Pt/C leads to outstanding ORR specific activity of Pt/M-TiO2. Notably, a fourfold increase of the specific activity is achieved with Pt/V-TiO2 relative to Pt/C. Furthermore, an accelerated durability test (ADT) of Pt/V-TiO2 demonstrates that this system is three times more durable than conventional Pt/C due to the metal-support interaction.

Simultaneous Photometric and Spectroscopic Analysis of V505 Lacertae, a Photospherically and Chromospherically Active Contact Binary Star

“…In contrast, the light curves of Sectors 56 and 57 indicate an O'Connell effect, with Max I being brighter than Max II. As noted in the Introduction, such a time-dependent O'Connell effect has frequently been explained by the presence of one or more cool (or hot) migrating spots on the photospheric surface of one or both of the system components (Beaky & Koju 2012;Debski 2020). In Section 4.3, we examine the time evolution of the starspot causing the O'Connell effect in detail by analyzing each of the TESS light curves observed for the three sectors.…”