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

The schematic diagram display that graphene working as a bed on the surface of CN for gold nanoparticles and charge transport. Due to graphene this materials have very large surface area and efficiently high number active surface side. [Display omitted] •Au-modified reduced graphene oxide (rGO) coupled graphitic carbon nitride.•Low-dimensional 0D/2D/2D photocatalytic system.•Water splitting and CO2 conversion to energy dense molecules.•Two-step two-electron way of water oxidization through intermediate H2O2 catalyzed by the adding rGO. 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.