Robust Wide Visible-Light-Responsive Photoactivity for H2 Production over a Polymer/Polymer Heterojunction Photocatalyst: The Significance of Sacrificial Reagent

A robust polymer/polymer surface heterojunction (SHJ) catalyst for wide visible-light-driven H-2 production is fabricated by a facile rotary evaporation of poly(3-hexylthiophene) (P3HT) solution containing graphitic carbon nitride (g-C3N4). The photocatalytic H-2 production activity of the obtained SHJ catalyst (P3HT/g-C3N4) is significantly affected by the types of sacrificial reagents, and ascorbic acid (AA) shows the best photoactivity among the commonly used sacrificial reagents. The SHJ catalyst containing 3 wt % P3HT gives a H-2 evolution activity up to 3045 mu mol/h in a saturated AA solution, which is similar to 491 times higher than that (6.2 mu mol/h) of P3HT/g-C3N4 without AA solution under gamma >= 500 nm light irradiation. Especially, the SHJ catalyst containing 3 wt % P3HT shows a record apparent quantum yield (AQY) of 77.4% at 420 nm light irradiation in the field of g-C3N4-based catalyst, and wide visible/NIR-light-responsive ability with AQY of 59.4%, 20.2%, 3.2% and 0.68% at 500, 600, 700 and 800 nm monochromatic light irradiation, respectively. The extremely high photoactivity is caused by the wide visible-light absorption, efficient charge transfer at the interface of P3HT/g-C3N4 and suitable oxidation half-reaction caused by the added AA as a sacrificial reagent. This study not only demonstrates a new direction for the solar fuel conversion over the large family of polymer-based semiconductors but also emphasizes the importance of oxidation half-reaction caused by the sacrificial reagent, which can significantly affect the photoactivity for H-2 production.