Enhanced Electron Transfer from the Excited Eosin Y to mpg-C₃N₄for Highly Efficient Hydrogen Evolution under 550 nm Irradiation

Abstract

Graphitic carbon nitride (g-C3N4) is a novel and stable metal-free photocatalyst that can generate H2 from water under visible light irradiation, but its activity is significantly limited due to the insufficient light absorption in the solar spectrum (weak absorption in the wavelength longer than 460 nm). In this paper, we demonstrate that the photoresponse of the mesoporous g-C3N4 (mpg-C3N4) can be greatly extended up to nearly 600 nm by sensitization with Eosin Y (EY). This sensitization photocatalyst demonstrates high and rather stable photocatalytic activity for H2 evolution under visible light irradiation, especially in the longer wavelength regions (450–600 nm). The apparent quantum efficiency (AQE) of 19.4% under 550 nm irradiation has been obtained. These results indicate that efficient electron transfer between excited EY molecules and mpg-C3N4 is achieved. The mpg-C3N4 with high surface area and nanoporous structure can greatly facilitate EY molecules assembly on the surface, thus promoting the activity via improved light harvesting.