Enhanced Surface Electron Transfer with the Aid of Methyl Viologen on the Co3O4-g-C3N4 Photocatalyst

Abstract

Due to the unique character of methyl viologen (MV 2+ ), namely, the electron oscillation that may occur in the process of MV 2+ reduction and oxidation, by means of MV 2+ addition, reacting system inert-atmosphere and electron donor addition, based on the peculiar contribution of MV 2+ with an electron oscillation characters, the stabilities and hydrogen evolution of the Co 3 O 4 -g-C 3 N 4 photocatalyst were greatly improved. Charge separation and electron transfer were more efficient under the condition of MV 2+ addition, as supported by fluorescence studies. The photoreduction of MV 2+ by Eosin Y (EY 2− ) can form a persistent methyl viologen radical cation (MV •+ ). MV 2+ , as an excellent electron relay, greatly facilitated electron transfer from the excited state 3 (EY 2− )* to the conduction band of Co 3 O 4 -g-C 3 N 4 . Accordingly, the excited state 3 (EY 2− )* was oxidized by MV 2+ ; this process effectively promoted the circulation regeneration of EY 2− , suppressed the generation of unstable intermediate EY •3− , and reduced the decomposition of EY.