Highly efficient photocatalytic H ₂ evolution using TiO ₂ nanoparticles integrated with electrocatalytic metal phosphides as cocatalysts

In this work, electrocatalysts like the metal phosphides Ni ₂ P, NiCoP, and FeP, can serve as cocatalysts of TiO ₂ to form efficient composite photocatalysts for hydrogen generation from an aqueous methanol solution. On comparing Ni ₂ P, NiCoP, and FeP and optimizing their proportions, the NiCoP(1 wt%)/TiO ₂ composite was found to exhibit the highest activity toward photocatalytic H ₂ production (1.54 μmol h ⁻¹  mg ⁻¹ ), which is about thirteen times that of the naked TiO ₂ nanoparticles. Mott-Schottky (MS) analysis indicated that the large upward shift or band bending of the Fermi energy level (E _F ) in metal phosphides was responsible for the enhanced activity of the composites. The steady-state photoluminescence (PL) spectra and photocurrent transient response further confirmed that the enhanced photoinduced charge transfer and band separation after TiO ₂ was integrated with the metal phosphides. Thus, these electrocatalysts were shown to be efficient cocatalysts that can replace noble metals as low-cost photocatalytic H ₂ production.