Carbon Nitride Polymers Sensitized with N-Doped Tantalic Acid for Visible Light-Induced Photocatalytic Hydrogen Evolution

Abstract

Carbon nitride (CN) polymers sensitized with N-doped tantalic acid were prepared by pyrogenation of the mixture of urea and tantalic acid at 400 °C. X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectrometry (EDS), and Fourier transform infrared spectroscopy (FTIR) results indicated that the CN polymers were successfully modified on the surface of the N-doped tantalic acid. UV−vis diffusion reflectance spectra (DRS) showed that the absorption edge of the CN polymers sensitized with N-doped tantalic acid red-shifted remarkably to the visible light region compared with bare tantalic acid. This new kind of CN polymers sensitized with N-doped tantalic acid showed a high photocatalytic activity and good stability for hydrogen evolution from an aqueous methanol solution under visible light (λ ≥ 410 nm) irradiation, and up to 4.8% of the apparent quantum yield was achieved at 420 nm. The protonic acidity of the tantalic acid makes themselves interact more intenser with the CN polymers, and easily hydrate in the aqueous solutions, so the separation probabilities of the photogenerated charge carriers would be improved.