Highly efficient hydrogen evolution over Co(OH)2 nanoparticles modified g-C3N4 co-sensitized by Eosin Y and Rose Bengal under Visible Light Irradiation

Abstract

In this work, non-noble metal cobalt hydroxide nanoparticles [Co(OH)2 NPs] implanted uniformly on graphitic carbon nitride (g-C3N4) as a co-catalyst for hydrogen evolution reaction (HER) by in-situ chemical deposition method were reported. After co-sensitized by Eosin Y (EY) and Rose Bengal (RB) dyes, this photocatalyst exhibited a comparatively low onset potential (0.26V) for HER and high photocatalytic HER activity under visible light irradiation. The g-C3N4 not only provided a large area and nanoporous structure for the confined growth of Co(OH)2 NPs, but also greatly facilitated EY and RB (ER) molecules assembling on its surface, which promoted the charge transfer from dye to co-catalyst. The PL spectra and lifetime test showed the strong interaction between Co(OH)2 NPs and g-C3N4 could enhance the transferr rate of the photogenerated electron to reduce the carries recombination. About 431.9μmol of hydrogen generated over ER co-sensitized Co(OH)2/C3N4 in 3h. The apparent quantum efficiencies (AQE) of 29.6 and 27.3% were achieved at 520nm and 550nm over Co(OH)2/C3N4, respectively. In addition, this co-sensitized photocatalyst showed satisfied stability for HER, no remarkable decay of activity was observed in 900min reaction. These results imply that Co(OH)2 is a stable and efficient cheaper co-catalyst for photo-HER.