Solid-state synthesis of ultra-small freestanding amorphous MoP quantum dots for highly efficient photocatalytic H2 production

Cocatalysts can tremendously boost the photocatalytic H-2 evolution performance by providing more active sites, accelerating the photogenerated charge separation, and benefiting the proton reduction reaction. To design and develop noble-metal-free cocatalysts with high performance in replace of noble metal Pt is significant for the practical application of solar H-2 production. In this work, we have developed a facile solid-state low-temperature phosphorization way to synthesize ultra-small freestanding amorphous MoP quantum dots with an average size of 2.7 nm. Compared with supported MoP heterostructures, the freestanding property and small size enable a compact contact between MoP with CdS, leading to a reduced Schottky barrier and improved photocatalytic activity. The highest photocatalytic performance of MoP/CdS composites is as high as 13.88 mmol h(-1) g(-1) with an apparent quantum yield (AQY 420 nm) 66.7% and it is 1.44-fold of that of Pt/CdS*. This ultra-high photocatalytic performance is attributed to the small size and amorphous structure of MoP with more exposed active sites and the highly efficient photogenerated charge separation. This low-temperature phosphorization method is expected to be applied to synthesize other freestanding ultra-small metal phosphides quantum dots.

Automated summary

A low-temperature phosphorization method was used to synthesize ultra-small freestanding amorphous MoP quantum dots, which showed high photocatalytic performance in H-2 evolution with CdS composites, attributed to their small size and amorphous structure.