Unique Mo2C–CdS–Co@C heterojunction integrated with redox cocatalysts and multiple active sites for efficient photocatalytic H2 generation

Photocatalytic water-splitting has encouraged great interest to obtain renewable H2 fuel via the transformation of solar energy. Although significant progress has been achieved, realizing efficient H2 evolution reaction (HER) with non-noble-metal photocatalysts is still challenging. Herein, we report a facile synthesis of Mo2C–CdS–Co@C heterojunction by anchoring CdS and Mo2C nanoparticles onto Co@C micro-flowers. The Co@C micro-flowers were composed of graphitic carbon nanoflakes partially embedded with Co, CoOx, Co9S8 nanocrystals and obtained through the carbonization of metanilic-anion intercalated Co(OH)2 precursor. Due to excellent visible-light harvesting capacity, efficient charge transmission and isolation caused by the existence of superior electron mediator (graphitic carbon) together with oxidation (CoOx) and reduction (Co, Co9S8, Mo2C) cocatalysts, as well as the plentiful H2-evolving active sites originating from the metal (Co), metal sulfide (Co9S8), and metal carbide (Mo2C), the Mo2C–CdS–Co@C hybrid micro-flowers delivered an exceptional HER (λ > 400 nm) activity of 760.58 μmol h−1 (10 mg), approximately 32 and 15 folds that of pristine CdS and platinum (3 wt%)-decorated CdS, respectively. Moreover, both the cycling and long-term photocatalytic tests confirm that the Mo2C–CdS–Co@C possesses an outstanding durability for H2 production. The study results might inspire the rational integration of cocatalysts to simultaneously optimize the charge trapping and H2-evolving kinetics for strengthening the photocatalytic HER activity efficiently.