Enhanced visible-light photocatalytic H2 production of graphitic carbon nitride nanosheets by dye-sensitization combined with surface plasmon resonance

Abstract

In this work, uniform dispersed gold nanoparticles (Au NPs) with an average diameter of ca. 25nm were loaded on graphitic carbon nitride nanosheets (g-C3N4 NSs) as co-catalysts via a facile one-step method. The morphology, composition, and crystallinity of the as-prepared products were well characterized by a variety of analytical methods. Results showed that the Au/g-C3N4 nanocomposite plasmonic photocatalysts with optimal loading of 2.0 wt% Au exhibited the highest photoactivity for H2 production under visible light irradiation (λ≥400nm) using triethanolamine (TEOA) as sacrificial reagents, which was almost 5.3 times higher than pure g-C3N4. In addition, through directly adding a cheap dye Eosin Y (EY) into the reaction suspension, the photocatalysis system showed a dramatically enhanced H2 evolution rate of 660.8 μmol/h•g that was about 3.5 times higher than that of the 2.0 wt% Au/g-C3N4 composite. It is proposed that the combination of dye sensitization with EY and plasmonic modification with Au NPs for g-C3N4 NSs could efficiently increase the density of photogenerated electron–hole pairs, facilitate the separation of charge carriers and consequently enhance the photoactivity for H2 evolution. The present work not only shows the possibility for the utilization of EY as an efficient photosensitizer and Au as H2 production co-catalysts to co-promote the photocatalytic performance of g-C3N4, but also offers a simple, low-cost, and convenient method for constructing other efficient plasmonic-metal/semiconductor heterostructures for plasmon-enhanced photocatalytic applications.