Active and Stable Oxygen Reduction Catalysts Prepared by Electrodeposition of Platinum on Mo₂C at Low Overpotential

Abstract

Decreasing the cost and improving the durability of polymer electrolyte membrane fuel cell (PEMFC) electrodes are two major unresolved challenges. Electrodeposition of low-dimensional Pt on transition metal carbide supports could be a way to simultaneously address both issues. Synthesis of low-dimensional Pt typically requires expensive equipment or techniques that are difficult to reproduce or scale. An electrodeposition-based technique to accomplish this goal is therefore highly desirable. The strong adhesion energy between Pt and the C sites on the α-Mo2C surface suggests that an electrochemical technique could be exploited for this purpose. Here, PtCl6 2– was electrodeposited onto an α-Mo2C support at low and high overpotentials (η). A dramatic increase in the electrochemical surface area and the mass activity of the oxygen reduction reaction (ORR) was observed when Pt was deposited at low overpotentials (+8 and +18 mV vs SCE) as compared to high overpotentials (−67 and −92 mV vs SCE). Indeed, catalysts prepared in the low-overpotential region achieved an ORR mass activity of 275 A/gPt and broke the linear relationship between mass activity and loading typically exhibited by these materials. Furthermore, catalysts prepared in the low-overpotential region exhibited superior stability out to 5000 cycles in an accelerated stress test (AST) as compared to samples prepared at higher overpotentials or by chemical reduction of Pt onto α-Mo2C and carbon supports.

Cu2+-Guided Construction of the Amorphous CoMoO3/Cu Nanocomposite for Highly Efficient Water Electrolysis

“…Featured with straightforwardness, power cost-effectiveness, and the short reaction period, electrodeposition has attracted much attention for the convenient synthesis of electrocatalysts. − Encouraged by the aforementioned concerns, in this work, a Cu 2+ -guided electrodeposition strategy was proposed to synthesize a Cu and amorphous low-valence CoMo oxide nanocomposite (denoted as a-CoMoO 3 /Cu) from the CuCl 2 , CoCl 2 , NH 4 Cl, and (NH 4 ) 6 Mo 7 O 24 mixed solution. In this strategy, Cu 2+ is the crucial key for the formation of the a-CoMoO 3 /Cu nanocomposite.…”

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

“…Also, they found that the catalyst prepared in the low-overpotential region exhibited the best stability after the accelerated stress test (AST, 5000 cycles) among all the contrast samples. 98 In addition, Lee et al selected highly conductive two-dimensional titanium carbide (Ti 3 C 2 ) as the support for Pt because of the expected SMSI between Pt and Ti 3 C 2 . Pt nanoparticles (4 nm) were loaded on three different Ti 3 C 2 supports including multi-, few-, and mono-layered Ti 3 C 2 (Fig.…”

Evaluation of Novel Fuel Cell Catalysts with Ultra-Low Noble Metal Contents towards Electrochemical Catalysis

“…[15][16][17] When commercial Nafion ® type membranes are employed, adequate humidification of the polymer electrolyte membrane and total water management during operation are crucial for PEMFC performance. [18][19][20] The water produced as a by-product will be used internally to maintain the membrane's hydration and prevent external water's excessive use for humidification. 2,19 Therefore, a PEMFC must be held when the by-product doesn't evaporate more quickly than the product.…”

“…[18][19][20] The water produced as a by-product will be used internally to maintain the membrane's hydration and prevent external water's excessive use for humidification. 2,19 Therefore, a PEMFC must be held when the by-product doesn't evaporate more quickly than the product. 4,20 PEMFCs must be operated at a temperature of less than 100 o C. Due to their low-temperature functioning and water requirement, pure hydrogen (with a low CO concentration) must be utilized in PEMFCs.…”

“…30 The deletion or at least reduction of Pt from the PEMFC electrodes has become necessary despite its enhanced performance, primarily because of the high material cost. 19 The need for more effective systems is partly driven by the slow cathodic response and problems with Pt stability. 11 Practically, the carbon support oxidizes throughout the long-term stability tests, eventually causing the Pt NPs to aggregate (reduce the surface-to-volume ratio), which lowers the system's overall performance.…”