Facile Synthesis of Lacunary Keggin-Type Phosphotungstates-Decorated g-C(3)N(4) Nanosheets for Enhancing Photocatalytic H(2) Generation

In this work, the lacunary Keggin-type phosphotungstates of [PW(9)O(34)](9-) (PW(9)) clusters were loaded onto the g-C(3)N(4) nanosheets (NSs) to synthesize the phosphotungstate clusters-decorated 2D heterojunction photocatalysts by using the electrostatic-force driven self-assembly process. The surface charge polarity of g-C(3)N(4) NSs was changed from a negative to a positive charge through the acidizing treatment. The positively-charged g-C(3)N(4) NSs allowed the negatively-charged PW(9) clusters to be adsorbed and deposited onto the g-C(3)N(4) NSs, forming the PW(9)/g-C(3)N(4) heterojunction NSs. The as-synthesized samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, and UV-VIS absorption spectra, respectively. The photocatalytic activity tests indicated that, upon simulated sunlight irradiation, the photocatalytic H(2)-generation rate of PW(9)/g-C(3)N(4) heterojunction NSs (~23.8 μmol h(−1)) was ~3.3 times higher than that of the pure g-C(3)N(4) NSs (~7.3 μmol h(−1)). The enhanced photocatalytic activity of PW(9) cluster-decorated g-C(3)N(4) NSs could be attributed to the enhanced separation process of the photoinduced charge-carriers, due to the Z-scheme-mediate charge transfer behavior across their hetero-interface.