Carbon dots/polyoxometalate/Pt as a ternary composite for electrocatalytic methanol oxidation

Abstract

Development of high-efficiency anode electrocatalysts remains a challenge for direct methanol fuel cells (DMFCs). Herein, carbon dots (CDs) and Co-substituted sandwich polyoxometalate K10[Co4(H2O)2(PW9O34)2]·20H2O (Co-POM) were selected as building blocks to construct a new ternary composite electrocatalyst CDs/Co-POM/Pt for application in the methanol oxidation reaction. CDs/Co-POM/Pt was characterized by FTIR, high resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectrum (EDX), element mapping, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results revealed that a nanoflower-like Pt nanostructure with high dispersion and uniformity was formed. The electrochemical experiments showed that CDs and Co-POM enhanced the electrocatalytic ability of Pt, and the highest peak current density of 7.98 mA cm−2 was obtained for CDs/Co-POM/Pt, corresponding to 3.6 times, 6.5 times and 10.8 times as high as that of CDs/Pt, Co-POM/Pt and pure Pt. Also CDs/Co-POM/Pt had good stability in the electrocatalytic process. This work paves a way for development of polyoxometalate-based electrocatalysts.