Construction 0D TiO2 nanoparticles/2D CoP nanosheets heterojunctions for enhanced photocatalytic H2 evolution activity

It is still of gigantic challenging to design and to optimize photocatalytic systems with cost-efficiency for photocatalytic hydrogen evolution from water splitting. Herein, noble-metal-free 2D CoP nanosheets were prepared by a phosphorization method using Co(OH)2 nanosheets as precursors, and then employed as photocatalytic cocatalyst and template to make 0D TiO2 nanoparticles in-situ grow on the surface for construction of 0D/2D TiO2/CoP hybrid by a simple hydrothermal method. The TiO2/CoP hybrid with the optimal ratio of CoP cocatalyst (1 wt.%) manifested significantly improved photocatalytic H2 evolution rate of 0.604 mmol g−1 h−1, which is tenfold in comparison to pure TiO2 (0.06 mmol g−1 h−1). The mechanism of performance enhancement was fully investigated and supposed that 2D CoP nanosheets cocatalyst can enhance the photo-absorption and provide more active sites for water reduction reaction; furthermore, 2D CoP nanosheets with smaller work function and high conductivity would form an Ohmic-junction with TiO2 nanoparticles, which can significantly accelerate the separation of photo-generated charge carriers and improve the exploitation of the photoexcited electrons in water redox reaction. This work is anticipated to impel more perspicacity into synthesizing innovative photocatalytic systems with 2D transition metal phosphides cocatalysts for attaining high photocatalytic H2 evolving pursuit.