Construction of Z-scheme heterostructure with enhanced photocatalytic H2 evolution for g-C3N4 nanosheets via loading porous silicon

Abstract

In this work, Z-scheme heterostructure were constructed over the visible light response g-C3N4 photocatalysts by loading Porous silicon (PSi) to enhance the photocatalytic H2 evolution performance. The synthesized Z-scheme g-C3N4/PSi composites with a PSi loading content of 2.50 wt% achieves the highest photocatalytic H2 evolution rate at 870.4 µmol h−1 g−1, which is about 2 times as high as the pure g-C3N4 with H2 evolution rate of 427.2 µmol h−1 g−1. Various techniques including XRD, SEM, TEM, FTIR, XPS, UPS, PL and electrochemical method were employed to demonstrate the successful construction of g-C3N4/PSi composites and to investigate the origin of the enhanced potocatalytic activity. The formed heterostructure between g-C3N4 nanosheets and PSi were verified to be the dominant reason for the enhancement of photocatalytic activity, resulting from the separation promotion of photogenerated charge carriers in a direct Z-scheme mechanism. This study presented a promising Z-scheme g-C3N4/PSi photocatalysts with promising H2 evolution performance, which might drive the progress of solar energy conversion technologies.