Photocatalytic hydrogen evolution over Erythrosin B-sensitized graphitic carbon nitride with in situ grown molybdenum sulfide cocatalyst

Abstract

Erythrosin B (EB) sensitized graphitic carbon nitride (g-C3N4) for photocatalytic hydrogen evolution was investigated using triethanolamine (TEOA) as an electron donor under visible light irradiation (λ > 420 nm). MoSx was loaded on g-C3N4 as a cocatalyst by an in situ photoreduction method during the photocatalytic reaction employing (NH4)2MoS4 as a precursor. EB-sensitized MoSx-g-C3N4 (EB-MoSx-g-C3N4) exhibits the higher activity and stability than both EB-sensitized g-C3N4 (EB-g-C3N4) and EB-sensitized MoSx (EB-MoSx). With deposition of 0.5 wt% MoSx, the photoactivity of EB-MoSx-g-C3N4 increases by more than 160 times after 2 h irradiation compared with that of EB-g-C3N4. The activity of EB-MoSx-g-C3N4 is 19.3 times as high as that of EB-MoSx after 10 h irradiation, and the former is much more stable than the latter. The highest apparent quantum yield for hydrogen evolution reaches 8.3% at 545 nm. The improved photoactivity and stability is owing to MoSx as an excellent hydrogen evolution cocatalyst and the efficient electron transfer among photoexcited EB, g-C3N4 and MoSx. The possible mechanism was discussed.