In situ synthesis of Co2P-decorated red phosphorus nanosheets for efficient photocatalytic H2 evolution

Abstract

Red phosphorus (RP) as an elemental semiconductor photocatalyst has been employed for photocatalytic hydrogen (H₂) production owing to its relatively narrow band gap (about 1.72 eV), excellent absorption features in the visible region, and favourable band structure. In this work, cobalt phosphide (Co₂P) as a noble-metal-free co-catalyst was first loaded on two-dimensional microporous RP nanosheets by a one-step in situ hydrothermal method. The investigations demonstrated that the introduction of Co₂P nanoparticles could facilitate the separation and migration of photogenerated charge carriers and provide numerous catalytic active sites for photocatalytic H₂ evolution. Besides, the stability of the composites was greatly enhanced by the formation of Co–P bonds between RP and Co₂P. As expected, 2% Co₂P/RP showed the highest H₂ evolution rate of 5997.5 μmol h⁻¹ g⁻¹, which was 7.0 times and 2.4 times higher than those of pristine RP (857.6 μmol g⁻¹ h⁻¹) and Pt/RP (2469.9 μmol g⁻¹ h⁻¹), respectively. Moreover, the one-step solution-phase synthesis technology can be extensively applied for other transition-metal-phosphide-based photocatalysts.