Small-sized Pt nanoparticles supported on hybrid structures of MoS2 nanoflowers/graphene nanosheets: Highly active composite catalyst toward efficient ethanol oxidation reaction studied by in situ electrochemical NMR spectroscopy

In this work, highly active MoS2 nanoflowers/graphene nanosheets (GNS) composites are successfully prepared through a simple hydrothermal method and are employed as Pt supports to prepare Pt/MoS2/GNS for ethanol oxidation. The catalyst is characterized both physically and electrochemically to investigate the effect of MoS2/GNS on Pt. Moreover, in situ electrochemistry - nuclear magnetic resonance, with the strength in structural characterization, quantitative analysis, and real-time measurement, is carried out to monitor molecular changes of reaction products and elucidate reaction mechanism of ethanol oxidation reaction, providing sampling resolution of 4s. Significantly, a small size of 5.4 nm Pt decorated Pt/MoS2/GNS is achieved. Pt/MoS2/GNS exhibits 2.1-fold increase in electrochemical active surface area, 2.2-fold increase in catalytic activity, and 2.0-fold increase in durability compared to commercial Pt/C during ethanol oxidation, which can be attributed to the synergistic effect of the interconnected nanoflower-on-nanosheet structure of MoS2/GNS, the better dispersion of Pt nanoparticles, and the interactions between substrate materials and Pt. The results suggest that Pt/MoS2/GNS could be an alternative electrocatalyst for efficient ethanol oxidation reaction. This work provides a promising strategy in the synthesis and monitoring of composite materials as high-performance ethanol oxidation catalysts.