Microwave assisted synthesis of high performance Ru85Se15/MWCNTs cathode catalysts for PEM fuel cell applications

The Ru85Se15 nanoparticles supported on commercial Vulcan XC-72R or multi-walled carbon nanotubes (MWCNTs) were synthesized by microwave assisted polyol method with different solution pH. The Ru85Se15 nanoparticles on citric acid (CA)-treated supports prepared at pH = 7 exhibited the most uniform particle distribution, higher degree of graphitization on supports, and four-electron ORR mechanism. Using lower loading of 0.138 mg Ru cm−2, the maximum power densities (Pmax) for the Ru85Se15/CA-MWCNTs and Ru85Se15/CA-XC72R were 380 mW cm−2 at 1430 mA cm−2 and 336 mW cm−2 at 1230 mA cm−2, respectively, with oxygen, while 166 mW cm−2 at 710 mA cm−2 and 126 mW cm−2 at 510 mA cm−2, respectively, with air. The Pmax of 103 mW cm−2 with air for the Ru85Se15/CA-MWCNTs could be retained (38% loss), while 46 mW cm−2 for Ru85Se15/CA-XC72R (64% loss) upon 6000 cycles. The four-electron ORR mechanism and highly graphitized MWCNTs might be responsible for the high performance and durability of Ru85Se15/CA-MWCNTs.

► The optimum pH for synthesis of Ru85Se15/MWCNTs was determined. ► The good cell performance and durability at ambient pressure and low catalyst load. ► Ru85Se15/supports were quantitatively characterized by Raman spectroscopy. ► The degree of graphitization was correlated to the performance and durability.