Improved Durability and Activity in Pt/Mo₂C Fuel Cell Cathodes by Magnetron Sputtering of Tantalum

Abstract

Cost reduction together with durability represent the primary challenges for cathode catalysts in polymer electrolyte membrane fuel cells (PEMFCs). The catalyst is often supported by carbon, which suffers from parasitic corrosion, particularly during start‐up and shut‐down operations. Transition metal carbides (TMCs) have attracted attention as a potential replacement for carbon supports because some of them have electronic structures likened to noble metals. Mo2C has shown promising activity as platinum support for the oxygen reduction reaction (ORR) but can suffer from oxidation and dissolution. Here, Mo2C supports are modified by surface tantalum (Ta) treatment using a variety of DC magnetron sputtering operating parameters. All supports modified by Ta showed improved corrosion resistance compared to the untreated support. Pt/Mo2C modified with Ta using a 500 V bias, 6 mTorr working pressure, and 2 min sputter time additionally showed improved kinetic current density and mass activity. Ta sputtering under these conditions were applied to the cathode side of a Pt/Mo2C membrane electrode assembly and showed significantly improved durability when subjected to an accelerated stress test. Ta‐modified Pt/Mo2C cathodes showed resistance to void formation and loss of electrochemical surface area. Ta magnetron sputtering can therefore be considered a viable surface treatment for improving the activity and stability of PEMFCs using Mo2C‐based supports.

Fe–N–C Boosts the Stability of Supported Platinum Nanoparticles for Fuel Cells

“…In the past, more stable materials including metal oxides, − carbides, − and graphitized carbon − have been explored as support for Pt-based nanoparticles. The Cherevko group studied the carbon effect on dissolution from 2D and 3D models of Pt/C catalysts, emphasizing the role of carbon on the Pt dissolution trends .…”

Inorganic non-carbon supported Pt catalysts and synergetic effects for oxygen reduction reaction

“…In the reported works, the novel non-carbon material supported Pt catalysts showed higher maximum power and durability than Pt/C catalysts in PEMFC tests. 118,124,153,277 In order to further speed up the application of ORR catalysts in PEMFCs, further elucidation of the interplay between the support material and the membrane components in a real MEA is required.…”

“…Oppositely, the following work demonstrated the modification of the Mo 2 C support by surface Ta treatment using a DC magnetron sputtering process, showing that Ta 2 O 5 partially covered Pt/Mo 2 C and resulted in improved activity and stability due to increased oxidation potential without sacrificing the dynamics. 277 Ma et al fabricated Co 6 Mo 6 C 2 on graphitized carbon as a support for a Pt catalyst. 278 The electronic structure of Pt was modified by the electron-donation effect arising from the carbide support, which also promoted the ORR activity.…”

The metal–support interaction effect in the carbon-free PEMFC cathode catalysts

“…Such a result demonstrates that without sacrificing the ORR kinetics, Ta alteration by magnetron sputtering can increase the oxidation potential, which is different from other reported TaC-modified Mo 2 C composites (TaC–Mo 2 C). 107…”

“…Such a result demonstrates that without sacricing the ORR kinetics, Ta alteration by magnetron sputtering can increase the oxidation potential, which is different from other reported TaC-modied Mo 2 C composites (TaC-Mo 2 C). 107 Besides, the 2D transition-metal carbides, especially MXenes (such as Ti 2 CT, where T represents functionalized termination), 109,110 have been considered as a potential support for the cathode catalyst of the fuel cell because of their metallic conductivity, electrochemical stability, and surface-charge property. [111][112][113][114] Our group prepared a MXene-based catalyst (o-MQFe) with FeN (Fig.…”