N-Annulated perylene-based organic dyes sensitized graphitic carbon nitride to form an amide bond for efficient photocatalytic hydrogen production under visible-light irradiation

In this work, two new N-annulated perylene-based organic sensitizers (PY-1 and PY-2) have been developed for dye-sensitized graphitic carbon nitride (g-C3N4) to remarkably enhance photocatalytic hydrogen production under visible-light irradiation (420 nm <= lambda <= 780 nm). The results showed that the H-2 production rates of the PY-1/g-C3N4/Pt and PY-2/g-C3N4/Pt were up to 5508.1 mu mol h(-1) g(-1) and 11,855.4 mu mol h(-1) g(-1) respectively, which were 8.98 and 19.3 times higher than that of the g-C3N4/Pt, respectively. Specifically, an impressive record apparent quantum efficiency (AQY) of 27.16% for PY-2/g-C3N4/Pt system was achieved at lambda = 550 nm monochromatic light irradiation. Moreover, the formation of amide bonds between dye molecules and g-C3N4 was firstly confirmed by FTIR spectrum and theoretical calculation. The amide bonds provided the electron transfer channels to significantly improve interface charge transfer and separation, thus resulting in a more efficient hydrogen production. More importantly, PY-1/g-C3N4/Pt and PY-2/g-C3N4/Pt displayed good stability under long-term irradiation and was favorable and significant for practical application. Our work indicated that dye sensitized g-C3N4 to form an amide bond is a promising strategy to realize the effective conversion of solar energy to hydrogen energy through molecular engineering.