Graphitic carbon nitride nanosheet coated carbon black as a high-performance PtRu catalyst support material for methanol electrooxidation

Abstract

PtRu supported on a C@g-C₃N₄ NS (g-C₃N₄ nanosheet coated Vulcan XC-72 carbon black) catalyst has been prepared by a microwave-assisted polyol process (MAPP). The results of electrochemical measurements show that the PtRu/C@g-C₃N₄ NS catalyst has excellent activity due to more uniform dispersion and smaller size of PtRu nanoparticles (PtRu NPs), and higher stability ascribed to the stronger metal–support interaction (SMSI) between PtRu NPs and the composite support. Physical characterisation using techniques such as X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) has indicated that the bulk g-C₃N₄ shell outside of the as-prepared C@bulk g-C₃N₄ (bulk g-C₃N₄ coated Vulcan XC-72 carbon black, C@bulk g-C₃N₄) indeed exfoliated to layered g-C₃N₄ nanosheets and formed a composite material of Vulcan XC-72 coated with g-C₃N₄ nanosheets. Furthermore, the results indicate that the mass catalytic activity of the PtRu/C@g-C₃N₄ NS catalyst substantially enhanced, which is a factor of 2.1 times higher than that of the PtRu/C catalyst prepared by the same procedure and the accelerated potential cycling tests (APCTs) show that the PtRu/C@g-C₃N₄ NS catalyst possesses 14% higher stability and much greater poison tolerance than as-prepared PtRu/C. The significantly enhanced performance of the PtRu/C@g-C₃N₄ NS catalyst is ascribed to the following reasons: the inherently excellent mechanical resistance and stability of g-C₃N₄ nanosheets in acidic and oxidative environments; the increased electron conductivity of the support by forming a core–shell structure of C@g-C₃N₄ NS; SMSI between metal NPs and the composite support. Based on this novel approach to fabricate a C@g-C₃N₄ NS hybrid nanostructure, many other interesting applications might also be discovered.