Phosphorus-enriched platinum diphosphide nanodots as a highly efficient cocatalyst for photocatalytic H2 evolution of CdS

Abstract

The number of catalytically active sites and their reaction efficiency are two crucial factors for cocatalyst applications in the field of photocatalytic hydrogen (H2) evolution of semiconductor materials. Herein, a novel phosphorus-rich platinum diphosphide (P-rich PtP2) nanodot was developed to efficiently improve the photoactivity of CdS by a facile phytic acid-assisted pyrolysis. The as-synthesized ultrafine PtP2 nanodots (2–5 nm) are evenly distributed on carbon layer (C) and further coupled with CdS to form PtP2@C/CdS photocatalyst via in-situ sulfurization methods. Under visible-light irradiation, the obtained PtP2@C/CdS(10 wt%) photocatalyst presents an optimum H2 evolution rate of 9.76 mmol g−1h−1 with apparent quantum efficiency (AQE) of 41.67% (420 nm), which is 2.2 and 34.8 times higher than that of Pt@C/CdS and blank CdS, respectively. Based on the results of related characterization and density functional theory calculations (DFT), the superior photocatalytic H2-evolution performance of PtP2@C/CdS can be ascribed to the formation of the electron-enriched Pδ− in P-rich PtP2 nanodots, which can serve as the effective H-proton adsorption active site to greatly enhance the photocatalytic activity. This work provides a new perspective into exploiting active site-enriched cocatalyst for the development of high-efficiency photocatalyst.