Enhancement of Catalytic Activity and Durability of Pt Nanoparticle through Strong Chemical Interaction with Electrically Conductive Support of Magnéli Phase Titanium Oxide

Abstract

In this study, we address the catalytic performance of variously sized Pt nanoparticles (NPs) (from 1.7 to 2.9 nm) supported on magnéli phase titanium oxide (MPTO, Ti4O7) along with commercial solid type carbon (VXC-72R) for oxygen reduction reaction (ORR). Key idea is to utilize a robust and electrically conductive MPTO as a support material so that we employed it to improve the catalytic activity and durability through the strong metal-support interaction (SMSI). Furthermore, we increase the specific surface area of MPTO up to 61.6 m2 g−1 to enhance the SMSI effect between Pt NP and MPTO. After the deposition of a range of Pt NPs on the support materials, we investigate the ORR activity and durability using a rotating disk electrode (RDE) technique in acid media. As a result of accelerated stress test (AST) for 30k cycles, regardless of the Pt particle size, we confirmed that Pt/MPTO samples show a lower electrochemical surface area (ECSA) loss (<20%) than that of Pt/C (~40%). That is explained by the increased dissolution potential and binding energy of Pt on MPTO against to carbon, which is supported by the density functional theory (DFT) calculations. Based on these results, we found that conductive metal oxides could be an alternative as a support material for the long-term fuel cell operation.

Activated Single‐Phase Ti4O7 Nanosheets with Efficient Use of Precious Metal for Inspired Oxygen Reduction Reaction

“…After the precious metal (Pt) is loaded, the O element on the surface of Ti 4 O 7 NSs becomes saturated, it could be inferred that the Ti 4 O 7 NSs are activated by Pt and interacts with it to have strong adsorption of oxygen (O 2 ads). [46][47][48][49] This phenomenon can be further verified by Figures S9d and S10b. Moreover, the electron interaction in metal-support is enhanced due to the unique photoelectric and -thermal features of Ti 4 O 7 , which facilitates the formation of SMSI, as will be discussed in detail in the following.…”

“…As shown in Figure 2j, the O element of VI−Pt/Ti 4 O 7 is well stacked over the whole selected area, which is sharply contrast to the unsaturated distribution of O element of Ti 4 O 7 NSs (Figure 2f). After the precious metal (Pt) is loaded, the O element on the surface of Ti 4 O 7 NSs becomes saturated, it could be inferred that the Ti 4 O 7 NSs are activated by Pt and interacts with it to have strong adsorption of oxygen (O 2 ads) [46–49] . This phenomenon can be further verified by Figures S9d and S10b.…”

Correlation between the Electrochemical Durability of Pt/C Catalysts and the Surface Functional Groups of the Support Carbon

“…Several strategies to improve the durability have been explored in recent years, including surface modifications by functionalizing the support through various treatments, 21 the use of corrosion-resistant supports such as highly graphitized carbon nanotubes (CNTs), 19 graphene 22 and graphite, 23 and the use of non-carbon supports. 24 The durability and activity of the Pt/C largely depend on the type of carbon support and the properties of the surface structure of the carbon. In relation to this, the metal−support interaction is of extreme importance since detachment of Pt particles from the support is a result of the weakening of the metal−support interaction by the instability of the carbon support.…”

Fe Ions-Doped TiO2 Aerogels as Catalysts of Oxygen Reduction Reactions in Alkaline Solutions

“…During heating, anatase and brookite irreversibly transform into rutile, and the stability of the crystalline modification depends on the size of its constituent crystallites [ 15 , 16 ]. Meanwhile, titanium oxides can have nanostructures with different phase compositions and morphologies, in particular as nanoparticles, nanorods, nanowires, nanotubes, and mesoporous structures [ 17 ], whereas they perform poorly when used as catalysts [ 18 , 19 , 20 , 21 , 22 , 23 , 24 ].…”