Ni(acac)2/Mo-MOF-derived difunctional MoNi@MoO2 cocatalyst to enhance the photocatalytic H2 evolution activity of g-C3N4

It is essential to construct bifunctional composite cocatalysts with earth-abundant metals for efficient transfer and separation of charge carriers, thus leading to the development of a photocatalyst with high H-2 evolution activity. Herein, MoNi@MoO2 composite cocatalysts were prepared by annealing Ni-doped Mo-MOF, and then decorating with g-C3N4 by grinding. The obtained MoNi@MoO2-8 %/g-C3N4 photocatalyst exhibited an optimum H-2 evolution rate of as high as 1.359 mmol g(-1) h(-1), 6.0 and 3.7 times than those of Ni/g-C3N4 and MoO2-8 %/g-C3N4, respectively. This improved activity can be ascribed to the bifunctional roles of MoNi@MoO2 and synergy between MoNi and MoO2. MoO2 acts as a reservoir to store electrons from g-C3N4; MoNi acts as surface-active sites to trap electrons from MoO2 and increase the proton reduction kinetics. This study would promote the development of other high-efficiency bifunctional cocatalysts to increase the photocatalytic H-2 evolution performance.