Fabrication of a composite of platinum, N-g-C₃N₄ and Ketjen Black for photo-electrochemical methanol oxidation

Recently N-doped graphitic carbon-incorporated g-C₃N₄ (denoted as N-g-C₃N₄) exhibits better electroconductivity and photo-catalytic property compared with pure g-C₃N₄ as a support material for Pt nanoparticles (NPs). A composite catalyst consisting of Pt nanoparticles and N-g-C₃N₄-modified KB was designed and fabricated. Pt nanoparticles were prepared through a solution plasma process; N-g-C₃N₄ was prepared by direct heating the mixture of urea and citric acid monohydrate and subsequently treated by hydrothermal method. Their chemical composition, particle size and microstructure were investigated by X-ray diffraction, X-ray photoelectron spectroscopy and transmission electron microscopy. Compared with the Pt/KB catalyst, ternary Pt/N-g-C₃N₄/KB nanocomposites exhibit excellent electrocatalytic properties for methanol oxidation owning to the significant synergistic effects of individual components. Once light irradiation was supplied, Pt/N-g-C₃N₄/KB catalyst exhibits exceptional forward peak current densities as high as 2800 mA mg_Pt ⁻¹. And Pt/N-g-C₃N₄/KB catalyst also shows better CO tolerance than Pt/KB. Such a Pt/N-g-C₃N₄/KB composite catalyst may bring new design ideas for photo-assisted direct methanol fuel cell in the future.