Uniform and Size‐Controlled Synthesis of Pt Nanoparticle Catalyst by Fluidized Bed Reactor Atomic Layer Deposition for PEMFCs

Pt nanoparticles (NPs) on a carbon support (Pt/C) are deposited by a simple fluidized bed reactor atomic layer deposition (FBR‐ALD) technique. The growth characteristics of the Pt NPs are investigated as a function of ALD cycles from 5 to 30 cycles. The excellent characteristics of FBR‐ALD offer highly dispersed and dense Pt particles with a size of ≈1 nm at low ALD cycles (5 cycles). However, as the number of ALD cycles increases above 5, the NPs increase in size and agglomerate due to preferential growth of incoming Pt NPs on previously deposited Pt surfaces. An electrochemical study shows that low ALD cycles (5 cycles) for the Pt/C catalyst result in a high electrochemical active surface area (ECSA) (114.67 m2 g−1). With increasing the number of cycles, ECSA is found to decrease, but still apparently higher than that of commercial Pt catalyst with the similar Pt wt% loading. Finally, ALD Pt/C catalysts with various cycles are applied to fuel cell testing for power generation. The electrode prepared with 20 ALD cycles of the Pt/C catalyst shows the best fuel cell performance (1.58 A cm−2 at 0.6 V) due to an adequate combination of activity and mass transfer characteristics of the electrode. Highly uniform and size‐controlled Pt nanoparticles on carbon black are synthesized by fluidized bed reactor atomic layer deposition (FBR‐ALD) through optimizing the fluidizing condition by a simple step. Growth characteristics of ALD‐Pt catalyst are systematically investigated as a function of cycle. Electrochemical and cell performance of Pt catalyst by FBR‐ALD are higher than that of the commercial Pt catalyst.