Novel PtCo alloy nanoparticle decorated 2D g-C₃N₄ nanosheets with enhanced photocatalytic activity for H₂ evolution under visible light irradiation

Novel two-dimensional (2D) graphitic carbon nitride (g-C₃N₄) photocatalysts decorated with PtCo bimetallic alloy nanoparticles (NPs) were prepared via an in situ chemical deposition method. The physical and chemical properties of the as-prepared PtCo/g-C₃N₄ samples were characterized by X-ray diffraction (XRD), ultraviolet-visible diffuse reflectance spectroscopy (DRS), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and surface photovoltage spectroscopy (SPV). The photocatalytic H₂ evolution experiments indicate that the PtCo alloy co-catalyst can effectively promote the separation efficiency of photo-generated charge carriers in g-C₃N₄, and consequently enhance the H₂ evolution activity. The 1.0 wt% PtCo/g-C₃N₄ nanosheet catalyst shows the highest catalytic activity, and the corresponding H₂ evolution rate is 960 μmol h^-1 g^-1, which is enhanced 2.9 times compared to that of pristine bulk Pt/g-C₃N₄ (330 μmol h^-1 g^-1) under visible light irradiation. The photocatalyst can keep stable and maintain catalytic activity after irradiation for 28 h. A possible photocatalytic mechanism of PtCo NPs on the enhancement of visible light performance is proposed to guide further improvement of other desirable functional materials.