Promoting visible-light photocatalytic activities for carbon nitride based 0D/2D/2D hybrid system: Beyond the conventional 4-electron mechanism

Photocatalysis is regarded as one of promising technology for future clean and sustaniable energy applications. Herein, we have fabricated Au-modified reduced graphene oxide coupled with carbon nitride (Au/rGO/g-C3N4) as novel 0D/2D/2D photocatalytic nanocomposites. The optimized sample 2Au/0.6rGO/g-C3N4 exhibits exceptional visible-light activity for water splititng and CO2 reduction with quantum efficiency of 3.82 % and 1.98 %, respectively. Electrochemistry and ultraviolent photoemission are combined to determine the band alignments and elaborate associated water splitting path-way mechanism. It is validated that due to intrinsic deep valence band position of g-C3N4, the obtained nanocomposites exhibit unusual two-step two-electron way of water oxidization through intermediate H2O2 catalyzed by rGO addition. The exceptional photoactivities are attributed to dual functions of enhanced charge separation and two-electron water oxidization facilitated by rGO and surface plasmon effect of decorated Au. Our work provides illuminations for low cost and high efficiency photocatalytic water splitting and CO2 reduction applications.