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Oxide-Core Pt-Shell Electrocatalysts for PEFCs: Photochemical Preparation Using SnO <sub/>2</sub> Nanoparticles
摘要： Core-shell electrocatalyst, in which a Pt atomic layer covers a nano-size core of a different metal, is attractive in reducing Pt usage for PEFC cathode electrocatalyst. Whilst such core-shell electrocatalysts exhibit very high mass activity for oxygen reduction reaction (ORR), their cost and durability still remain as a challenge. If inexpensive and thermochemically-stable conductive oxide could be applied to the core instead of a noble metal, cost reduction and durability improvement of such core-shell electrocatalysts may be expected. In this study, we try to develop oxide-core Pt-shell electrocatalysts by directly depositing Pt on SnO2 at an atomic level via a photochemical preparation procedure. SnO2 cores with a diameter down to ca. 3 nm could be prepared by comparing various preparation procedures of SnO2 and types of fillers. Electrochemical activities of such oxide-core Pt-shell electrocatalysts are characterized and discussed.
关键词： PEFC,SnO2,photochemical preparation,Pt-shell,Core-shell electrocatalyst
更新于2025-09-23 15:21:01
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Evaluation of Dry-Wet Transition in PEFC Under Load Changes Based on Laser Spectroscopy Using Fiber-Optic Probe
摘要： To avoid the membrane dryout and performance degradation of polymer electrolyte fuel cells (PEFCs) under low-humidity conditions, it is necessary to understand the dynamic water transport within working cells. In this study, we have developed a real-time gas sensing system with a single-ended fiber-optic probe based on tunable diode laser absorption spectroscopy (TDLAS), to measure the water vapor distribution in narrow channels of fuel cells with high accuracy and high temporal resolution. This sensor was used to evaluate the dry-wet transient phenomena in the anode flow channel of a PEFC during low-humidity and load change operations. The technique showed the water vapor concentration in the anode channel has a large temporary drop when the current density increases and the voltage undershoot occurs. We concluded that the TDLAS-based gas sensing technique enables the detection of instantaneous fluctuations of water concentration in the flow channel observed after step changes of current density.
关键词： load changes,fiber-optic probe,dry-wet transition,PEFC,TDLAS
更新于2025-09-23 15:19:57
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Drying process of water in a Nafion membrane embedded in the fuel cell analyzed by coherent anti-Stokes Raman scattering spectroscopy
摘要： A coherent anti-Stokes Raman scattering (CARS) spectroscopy system was designed to measure the transient behavior of the humidi?cation of a Na?on membrane used in a polymer electrolyte fuel cell (PEFC). We observed a variation in the intensity of the O–H stretching vibration peak of water during dry and wet gas ?ow. From our measurements, we found that our system showed a high time resolution enough to measure humidi?cation variation in a Na?on membrane in a PEFC. The high acquisition rate revealed the nonequilibrium process of the dehydration or hydration of the Na?on membrane through the temporal variation in the intensity of the O–H stretching vibration peak. The peak consisted of three peaks, suggesting that water molecules hydrated with di?erent bonding energies. The transient behavior of the peaks was probably attributed to the motion of hydration molecules in the proton channel. ? 2018 The Japan Society of Applied Physics
关键词： CARS spectroscopy,O–H stretching vibration,hydration,Na?on membrane,PEFC
更新于2025-09-04 15:30:14