Metal-free broad-spectrum PTCDA/g-C3N4 Z-scheme photocatalysts for enhanced photocatalytic water oxidation

Exploiting highly-efficient, broad-spectrum responsive and noble-metal-free water oxidation photocatalyst is a major challenge in the field of photocatalysis. Herein, we tackle this challenge by synthesizing Z-scheme PTCDA/g-C3N4 photocatalysts, which can absorb light with wavelength short than 600 nm, for visible light photocatalytic O-2 production from water. Owing to the evident conduction and valance band energy level difference between PTCDA and g-C3N4, the PTCDA/g-C3N4 photocatalysts exhibit efficient charge carrier separation through a Z-scheme mechanism, as demonstrated by the transient photocurrent responses and time-resolved fluorescence decay spectra analysis. Benefitting from the synergetic effect of the broad visible light absorption capacity and efficient charge separation, the optimized PTCDA/g-C3N4 photocatalyst shows the highest O-2 evolution rate of 847 mu mol.h(-1) under visible light irradiation in the presence of Co3O4 as a cocatalyst and AgNO3 as the sacrificial reagent. An apparent quantum yield of 4.5% was achieved under monochromatic light irradiation at 420 nm.