The preparation of 2D TpPa-COF/2D g-C3N4 heterojunction via in-situ growth for enhanced visible-light photocatalysis

Designing efficient heterojunction structure is an effective strategy to improve the performance of photocatalysis. The reasonable structure of photocatalyst and good interface contact, especially the two-dimensional/two-dimensional (2D/2D) composite heterojunction is considered as one of the most representative heterojunctions. Herein, a series of the 2D TpPa-COF/2D g-C3N4 composite materials are prepared through the in-situ reaction. A series of characterizations, such as X-ray diffraction (XRD), Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) have verified their 2D/2D heterojunction structure. Compared with TpPa-COF and g-C3N4, the absorption edge of TpPa-COF/g-C3N4 composites was extended to 650 nm. The TpPa-COF/g-C3N4 composite exhibited high photocatalytic H2 evolution rate of 17600 μmol g−1·h−1 under visible-light (λ ≥ 420 nm) irradiation, which is 2.3 times and 1760 times of TpPa-COF and g-C3N4, respectively. The apparent quantum yield (AQY) of TpPa-COF/g–C3N4–20 still maintains 0.4% under 700 nm light irradiation. The TpPa-COF/g-C3N4 composite photocatalyst also exhibited enhanced visible-light activity for overall water splitting with H2 and O2 evolution in a stoichiometric ratio of 2:1. This work provides an important strategy for designing efficient heterojunction photocatalysts.