AuPd bimetallic nanoparticles decorated graphitic carbon nitride for highly efficient reduction of water to H₂ under visible light irradiation

In this work, a new AuPd bimetallic cocatalyst decorated graphitic carbon nitride (g-C₃N₄) photocatalysts with high H₂ evolution activity was synthesized via an in situ chemical deposition method. The physical and photophysical properties of the as-prepared AuPd/g-C₃N₄ were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Transmission electron microscope (TEM), Ultraviolet-visible diffuse reflection spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), electron spin resonance (ESR) and surface photovoltage spectroscopy (SPV). The photocatalytic H₂ evolution experiments indicate that the AuPd bimetallic co-catalysts can effectively promote the separation efficiency of photo-generated charge carriers in g-C₃N₄, and consequently enhance the H₂ evolution activity. The 0.5 wt% AuPd/g-C₃N₄ catalyst shows the highest catalytic activity, and corresponding H₂ evolution rate is 326 μmol h^-1 g^-1, which are enhanced by 3.5 and 1.6 times compared with that of pristine Au/g-C₃N₄ and Pd/g-C₃N₄ under visible light irradiation. The photocatalyst can maintain photocatalytic activity after 4 cycles. A possible photocatalystic mechanism of AuPd bimetallic nanoparticles (NPs) on the enhancement of visible light performance is proposed to guide further improvement for other desirable functional materials.