Zirconium-Based Compounds for Cathode of Polymer Electrolyte Fuel Cell

Abstract

Zirconium-based compounds, such as ZrO x N y , have been investigated as a cathode of polymer electrolyte fuel cells. ZrO x N y was prepared using radio-frequency ͑rf͒ magnetron sputtering under an Ar + O 2 + N 2 with heating the substrate. The solubility of ZrO x N y deposited at 500°C was less than 5 ϫ 10 −8 mol dm −3 in 0.1 mol dm −3 H 2 SO 4 at 30°C under atmospheric condition, indicating that ZrO x N y had a high chemical stability in acidic media. The effect of the heat-treatment during the film deposition on the catalytic activity for oxygen reduction reaction ͑ORR͒ and the properties of ZrO x N y has been examined. The ORR current density on ZrO x N y deposited at a substrate temperature of 800°C was ϳ30 times greater than that at 50°C. The dependence of both the ORR current density at 0.4 V and the apparent activation energy of the ORR at 0.4 V on the substrate temperature changed near 500°C. The crystalline structure of ZrO x N y also changed near 500°C. In addition, the catalytic activity for the ORR increased with the increasing crystallinity and decreasing ionization potential of the specimens. Therefore, the crystalline structure, the crystallinity, and the ionization potential might affect the catalytic activity for the ORR.

ZrO2Based Oxygen Reduction Catalysts for PEMFCs: Towards a Better Understanding

“…In contrast, the two depicted catalysts based on Zr(acac) 4 /KB precursor clearly exhibit tetragonal ZrO 2 phases. Generally, in a forthcoming study within our group, it was found that Zr(acac) 4 precursor tends to develop crystalline ZrO 2 phases already at lower heat-treatment temperatures compared to ZrOPc/KB. Nevertheless, both precursors lead to isostructural ZrO 2 nanoparticles for heat treatments at ≥750…”

“…• C. 24 Exemplary transmission electron microscopy (TEM) micrographs are shown for ZrOPc/KB 1000 PO and Zr(acac) 4 /KB 950 PO ( Figure 3). The average particle sizes of 9 ± 2 nm for the former and of 10 ± 2 nm for the latter are virtually identical (number based averages obtained by counting at least 100 particles in each case).…”

“…All materials in this study which are based on ZrOPc precursor exhibit particle sizes ranging from ≈4 nm at low heat-treatment temperatures (500 PO and 750 RED) to ≈9 nm at higher temperatures (1000 PO). Those stemming from Zr(acac) 4 precursors range from ≈4 nm (500 PO and RED) to ≈10 nm (950 PO). For catalysts heat treated below 500…”

Toyota MIRAI Fuel Cell Vehicle and Progress Toward a Future Hydrogen Society

“…[10][11][12] At the same time, non-noble metal catalysts, oxide catalysts, and carbon alloys are being actively researched. 13,14 The Pt loading in the anode catalyst layer is also expected to be reduced after Pt reduction is realized at the cathode. For the perfluorinated membrane and the GDL, the chemistry and processes for manufacturing are nearly fixed, and cost reductions will come with scale.…”

Morphology-Controlled Nitrogen-Containing Polymers as Synthetic Precursors for Electrochemical Oxygen Reduction Fe/N/C Cathode Catalysts

“…For both reaction pathways, non-precious metal (NPM) catalysts are desired, considering the cost and scarcity of precious metals. The catalysts obtained by pyrolyzing Fe, N, and C-containing precursors have been widely studied, while oxide-based catalysts also constitute another class of NPM catalysts [4][5][6]. This review article describes an effective approach to obtain a highly active Fe/N/C catalyst.…”