Facile construction of CuO/g-C3N4 heterojunctions with promoted photocatalytic hydrogen generation behaviors

Abstract

The core issue of photocatalytic H2 generation from water decomposition is to explore high activity, ultra stability and environment-friendly photocatalytic materials. Graphitic carbon nitride (g-C3N4, GCN) is preferred by global scientists for the diversified superiorities, such as the characteristic of flake graphite-phase fabric, competitive cost, non-poisonous, ideal bandgap (∼2.7 eV) and decent stability. Nevertheless, by reason of the deficiencies in small specific surface area and rapid photo-excited charge pairs recombination, photocatalytic hydrogen evolution activity of g-C3N4 is undesirable and it cannot be put into large-scale industrial production for these reasons. Construction of heterojunctions to boost electrons/holes (e-/h+) segregation efficiency is identified as a resultful tactic to promote the activity of g-C3N4. In current work, CuO/g-C3N4 with disparate CuO/g-C3N4 mole ratio (0.5%, 1%, 1.5%, 2%) were prepared through an impregnating strategy and investigated via various methods. Photocatalytic properties of CuO/g-C3N4 (CuO/CN) photocatalysts exert superior H2 evolution rate and consistency under solar light illumination. The optimal H2 evolution activity with non-cocatalyst is 130.1 µmol·g−1·h−1 upon the 1.5% CuO/CN, realizing 46.1 folds as fast as that of GCN (2.8 µmol·g−1·h−1). Coupling with CuO is confirmed to narrow bandgap of the samples, thus enhancing the light absorptivity and utilization. Besides, photo-stimulated e-/h+ pairs have acquired more efficient separation after formation of CuO/g-C3N4 heterojunctions. The method for preparation of S-scheme CuO/g-C3N4 heterojunction catalysts furnishes a perception of boosting the photocatalytic H2 generation rate through coupling with transition metal oxides.