High photocatalytic performance of ruthenium complexes sensitizing g-C3N4/TiO2 hybrid in visible light irradiation

Abstract

Ruthenium (II) was firstly coordinated with 4,4′-dicarboxy-2,2′-bipyridine for 4,4′-dicarboxy-2,2′-bipyridine ruthenium and then bonded with g-C3N4 (designated as RuC@g-C3N4), and were finally loaded in TiO2 (designated as RuC@g-C3N4/TiO2) by the solvothermal method. The obtained ruthenium complexes sensitizing g-C3N4/TiO2 hybrid exhibited high photocatalytic performance under the visible light irradiation. The morphologis of photocatalysts were characterized by field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HRTEM) with element mapping and Brunauer-Emmett-Teller (BET). The compositional structure and chemical composition were analyzed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectra (FTIR). Photoluminescence (PL) spectra indicated the addition of the ruthenium complexes enhanced the photo-generated electron-hole separation and transport, and the photocatalytic activity was evaluated by degradation of Methyl Blue (MB) under visible light irradiation. The results suggest that the minor amounts of ruthenium complexes sensitizing can usefully improve the photocatalytic performance, and the optimal theory mass ratio of TiO2 to RuC@g-C3N4 of 12:1 presents the best catalytic performance, and it is nearly 1.9 times as high as the conventional reported optimal g-C3N4/TiO2 hybrid with the same mass ratio of TiO2/g-C3N4 of 12:1 under visible light irradiation. At the end of article, a possible photocatalytic mechanism was discussed based on the experimental results.