Ultrafine Pt Nanoparticles Stabilized by MoS2 / N-doped Reduced Graphene Oxide as Durable Electrocatalyst for Alcohol Oxidation and Oxygen Reduction Reactions.

Direct alcohol fuel cells (DAFCs) play a pivotal role in synthesis of catalysts due to their low cost, high catalytic activity, and long durability in half-cell reactions, which include anode (alcohol oxidation) and cathode (oxygen reduction) reactions. However, platinum catalysts suffer from CO tolerance, which affects their stability. The present study focuses on ultrafine Pt nanoparticles stabilized by flower-like MoS2/N-doped reduced graphene oxide (Pt@MoS2/NrGO) architecture was developed, via a facile and cost-competitive approach that performed through hydrothermal followed by wet-reflux strategy. Fourier transform infrared spectra, X-ray diffraction patterns, Raman spectra, X-ray photoelectron spectra, field-emission scanning electron microscope and transmission electron microscope were verified the conversion to Pt@MoS2/NrGO. Pt@MoS2/NrGO was applied as a potential electrocatalyst toward anode reaction (liquid fuel oxidation) and cathode reaction (oxygen reduction). In anode reaction, Pt@MoS2/NrGO showed superior activity toward electro-oxidation of methanol, ethylene glycol and glycerol with the mass activities of 448.0, 158.0 and 147.0 mA/mgPt, respectively, approximately 4.14, 2.82, and 3.34 times that of a commercial Pt-C (20%) catalyst. The durability of Pt@MoS2/NrGO catalyst was tested via 500 potential cycles, demonstrating less than 20% of catalytic activity loss for alcohol fuels. In the cathode reaction, ORR results showed excellent catalytic activity with higher half-wave potential at 0.895 V vs. a reversible hydrogen electrode for Pt@MoS2/NrGO. The durability of Pt@MoS2/NrGO catalyst was tested via 30,000 potential cycles, showed only 15 mV reduction in the half-wave potential, whereas the Pt@NrGO and Pt-C catalysts were experienced a much greater shift (Pt@NrGO, ∼23 mV; Pt-C, ∼20 mV).