Synergistic enhancement of π-electron density in graphitic carbon nitride for significantly improved photocatalytic hydrogen evolution under visible-light irradiation

Abstract

In this work, a synergistic strategy integrated elemental doping and defect engineering has been developed to modulate the electronic and bandgap structure of g-C3N4 by controlling its conjugated aromatic system. Experimental analysis and theoretical calculations confirm that the generation of imbalanced spatial distributions of charge carriers not only greatly increases the π-electron availability, but also decreases the energy barrier for hydrogen adsorption due to the synergistic effect of the high valence electron of the W dopant and the decreased electronegativity by two-coordinated nitrogen defects, which strengthens the charge transfer efficiency and favors the light capturing capability. The combined benefits of the electronic, optical and textural modification lead to a significant improvement of photocatalytic activity of 3.3 mmol h−1 g−1 for hydrogen evolution under λ ≥ 400 nm light irradiation, about twentyfold enhancement than that of pristine g-C3N4. Such proposed synergistic strategy provides a promising route to promote the performance of g-C3N4 for potential applications in solar energy conversion.