▎ 摘　　要

In this paper, the composite film based on Keggin-type Vanadium-substituted polyoxometalates decorated by graphene, tris(2.2-bipyridine) ruthenium(II) [Ru(bpy)(3)(2+)] is prepared by the layer-by-layer self-assembly method. The UV-vis spectra is engaged to demonstrate the uniform and stable growth process. The surface morphology and roughness are examined by using atomic force microscopy and scanning electron microscope. The results show that the nanoparticles are uniformly dispersed on the fold shaped surface of composite film. Xray photoelectron spectra are used to identify the chemical composition of the composite film. The result confirms that Ru(bpy)(3)(2+), graphene and polyoxometalates are successfully deposited on the film. Amperometric and cyclic voltammograms detections are used to investigate the electrochemical properties and sensing ability for ascorbic acid (AA). The results indicate that the composite film has great sensing performance to AA in the phosphate buffer solution (PBS), the linear range is from 7.5 x 10(-7) to 2.07 x 10(-4) M, detection limit and sensitivity are 1.0 x 10(-7) M and 0.24 mu M/mu A, respectively. And it also shows favorable selectivity with common interfering species. The composite film is used for AA determinations in real samples with satisfactory results.