Junction of porous g-C3N4 with BiVO4 using Au as electron shuttle for cocatalyst-free robust photocatalytic hydrogen evolution

Z-scheme g-C3N4/Au/BiVO4 photocatalyst has been prepared successfully by assembling gold nanoparticles on the interface of super-thin porous g-C3N4 and BiVO4, which exhibits outstanding photocatalytic performance toward hydrogen evolution and durable stability in the absence of cocatalyst. The highest photocatalytic hydrogen production rate of g-C3N4/Au/BiVO4 was about 410.0 mu mol g(-1) h(-1), which largely beyond that obtained of g-C3N4/BiVO4 (23.3 mu mol g(-1) h(-1)), Au/g-C3N4 (244.6 mu mol g(-1) h(-1)) and pristine g-C3N4 (2.2 mu mol g(-1) h(-1)). The optimal apparent quantum efficiency was counted to be 6.8% at lambda = 420 nm and 1.1% at lambda = 600 nm. Moreover, the photocatalytic property of g-C3N4/Au/BiVO4 could remain unchanged almost with 50 h in 5 cycles. The improvement of photocatalytic H-2 yield is attributed to the result of rapid separation of photogenic carriers in space and surface plasmon resonance effect of Au nanoparticles. In combination of photoelectrochemical measurement, active species capture experiment and electron paramagnetic resonance spectra, the underlying mechanism was illuminated. The pathway of charge carrier migration between semiconductor photocatalysts could be changed to Z-system through Au as an electron intermediate, which could not only benefit to maintain outstanding redox capability but also help to accelerate photo-generated carrier separation, and thus improve the photocatalytic activity.