Novel S-scheme RP/NiCo-LDH composite with remarkably enhanced photocatalytic activity for H2 evolution under visible-light irradiation

Abstract

A novel red phosphorus/nickel cobalt layered double hydroxide (RP/NiCo-LDH) heterojunction was successfully prepared and exhibited an excellent photocatalytic performance for hydrogen evolution. The formation of an S-scheme between purified RP and the NiCo–LDH effectively promoted the generation of an electric field at the interface between RP and the NiCo-LDH. The existence of an internal electric field can promote the migration of photoexcited carriers from the conduction band of pure RP to the valence band of the NiCo-LDH, thus effectively inhibiting the recombination efficiency of electron/hole pairs. Under simulated visible-light irradiation, the hydrogen evolution activity of the 70 wt% NiCo-LDH composite catalyst RP/NiCo-LDH reached 32.8 mmol g⁻¹ at 5 h, which was 6.41 times that of pure NiCo-LDH. The RP/NiCo-LDH composite photocatalyst was characterized using a series of characterization techniques. Among them, UV absorption spectra, fluorescence and photoelectrochemical experiments showed that the absorption rate and the electron-transfer rate of the RP/NiCo-LDH composite catalyst were significantly higher than that of the pure RP and NiCo-LDH. Therefore, RP/NiCo-LDH composite photocatalysts open up a new route for the development of non-noble metal photocatalysts.